# Seminar 11: Spinal Cord Disorders ## Neurology Clerkship --- ## Learning Objectives By the end of this seminar, students will be able to: 1. Localize lesions to specific spinal cord levels using motor, sensory, and reflex findings 2. Recognize and differentiate the major spinal cord syndrome patterns including complete transection, Brown-Sequard, central cord, and anterior cord syndromes 3. Evaluate and emergently manage acute spinal cord compression using appropriate imaging and medical interventions 4. Differentiate myelopathy from peripheral neuropathy, radiculopathy, and other causes of weakness through systematic clinical reasoning 5. Identify inflammatory, vascular, infectious, and degenerative conditions affecting the spinal cord and apply appropriate diagnostic workups 6. Apply urgent management principles for spinal cord emergencies including epidural abscess and cauda equina syndrome --- ## Seminar Outline ### Section 1: Spinal Cord Anatomy The spinal cord is a highly organized cylindrical structure in which specific tracts occupy predictable positions within the cross-sectional anatomy, making precise localization of lesions possible through careful clinical examination. The lateral corticospinal tracts, situated in the lateral white matter, carry voluntary motor commands from the cerebral cortex to the lower motor neurons and represent the primary pathway for volitional movement. The dorsal columns, located in the posterior white matter, transmit proprioceptive information, vibratory sense, and discriminative light touch from the ipsilateral body and ascend uncrossed to the brainstem before decussating in the medulla. The spinothalamic tracts, found in the anterolateral white matter, convey pain and temperature sensation and are notable for decussating at or near the level of entry into the spinal cord, a feature that has critical implications for lesion localization. The anterior horn cells house the lower motor neurons that directly innervate skeletal muscle, and autonomic fibers coursing through the cord mediate bladder, bowel, and sexual function. The vascular supply of the spinal cord follows a consistent but clinically important pattern. The anterior spinal artery, a single midline vessel arising from the vertebral arteries, supplies the anterior two-thirds of the spinal cord, encompassing the corticospinal tracts, spinothalamic tracts, and anterior horn cells. The paired posterior spinal arteries supply the posterior one-third of the cord, primarily the dorsal columns. The artery of Adamkiewicz is the major segmental feeder to the anterior spinal artery, typically arising from the left side between T9 and L2, and is of critical surgical importance during thoracic and abdominal aortic procedures. The thoracic spinal cord represents a watershed zone between the territories of the radicular arteries and is therefore the most vulnerable segment to ischemic injury, a fact that explains the predilection for thoracic cord infarction in states of systemic hypoperfusion. Knowledge of spinal cord levels and their corresponding functions is essential for clinical localization. The phrenic nerve, originating from C3 through C5, innervates the diaphragm, and lesions above this level cause respiratory failure. The C5 and C6 segments supply the biceps and wrist extensors, while C7 through T1 segments control hand intrinsic muscles. The sympathetic outflow arises from T1 through L2, and disruption at these levels can produce Horner syndrome or autonomic dysregulation. The L2 through L4 segments innervate the quadriceps for knee extension, L5 and S1 control ankle dorsiflexion and plantarflexion respectively, and the sacral segments S2 through S4 govern bowel, bladder, and sexual function. This somatotopic organization allows clinicians to determine the level of a spinal cord lesion with remarkable precision based on the pattern of motor and sensory deficits. Deep tendon reflexes provide additional localizing information and are among the most reliable clinical tools for identifying the spinal cord level of a lesion. The biceps reflex is mediated by the C5 and C6 segments, the triceps reflex by C7 and C8, the patellar or knee-jerk reflex by L3 and L4, and the Achilles or ankle-jerk reflex by the S1 segment. The bulbocavernosus reflex, testing the S2 through S4 segments, is particularly important in the evaluation of spinal shock and cauda equina syndrome. The presence of hyperreflexia below a lesion indicates an upper motor neuron process, while areflexia at the level of the lesion suggests lower motor neuron involvement at that segment. An inverted reflex, in which a reflex is absent at one level but exaggerated at levels below, can pinpoint the exact level of cord compression. Panel A: Detailed cross-sectional diagram of the spinal cord showing the positions of the lateral corticospinal tracts, dorsal columns, spinothalamic tracts, anterior horn cells, and autonomic fibers with color-coded functional zones. Panel B: Anterior and posterior views of the spinal cord vascular supply illustrating the anterior spinal artery, paired posterior spinal arteries, artery of Adamkiewicz at T9-L2, and watershed zones with annotations of vulnerability to ischemia. Panel C: Full-length diagram of the spinal cord with labeled segmental levels showing key functional landmarks including diaphragm at C3-C5, biceps at C5-C6, hand intrinsics at C7-T1, sympathetic outflow at T1-L2, quadriceps at L2-L4, ankle at L5-S1, and sacral function at S2-S4. Panel D: Clinical examination illustration showing deep tendon reflex testing at the biceps, triceps, patellar, Achilles, and bulbocavernosus levels with corresponding spinal segments and expected responses in upper versus lower motor neuron lesions. --- ### Section 2: Spinal Cord Syndromes Complete spinal cord transection results in total loss of all neurological function below the level of the lesion and represents the most devastating form of spinal cord injury. Motor examination reveals complete paralysis below the affected segment, and sensory examination demonstrates total loss of all modalities including pain, temperature, light touch, proprioception, and vibration below the lesion level. In the acute phase, spinal shock produces flaccid paralysis and areflexia below the lesion, which may initially mimic a lower motor neuron process; however, as spinal shock resolves over days to weeks, upper motor neuron features emerge including spasticity, hyperreflexia, and extensor plantar responses. Autonomic dysfunction is invariable and includes bowel and bladder dysfunction and, in cervical and upper thoracic injuries, loss of sympathetic tone leading to neurogenic shock with bradycardia and hypotension. The most common causes of complete transection include severe trauma, large tumors, and extensive transverse myelitis. Brown-Sequard syndrome results from hemisection of the spinal cord and produces a characteristic pattern of crossed neurological deficits that elegantly reflects the anatomy of the ascending and descending tracts. On the ipsilateral side, patients develop weakness due to disruption of the lateral corticospinal tract, which has already decussated in the medulla, and loss of proprioception and vibratory sense due to interruption of the ipsilateral dorsal column. On the contralateral side, pain and temperature sensation are lost because the spinothalamic tract crosses at or near its level of entry, meaning that fibers entering from the opposite side are disrupted by the hemisection. This syndrome is most commonly caused by penetrating injuries such as stab wounds but can also result from multiple sclerosis, spinal cord tumors, and epidural hematomas. The prognosis for Brown-Sequard syndrome is generally the most favorable among the incomplete cord syndromes, with many patients recovering ambulatory function. Central cord syndrome is the most common incomplete spinal cord injury and characteristically produces greater weakness in the upper extremities than in the lower extremities. This pattern reflects the somatotopic organization of the corticospinal tracts within the cervical cord, where fibers destined for the upper extremities are located more centrally and are therefore more vulnerable to central cord damage, while fibers to the lower extremities are positioned more peripherally and are relatively spared. Sensory deficits are variable and may follow a cape-like distribution affecting the shoulders and upper limbs. The classic mechanism is a hyperextension injury in an older patient with pre-existing cervical spondylosis, in which the cord is compressed between anterior osteophytes and a posteriorly buckled ligamentum flavum. The prognosis for central cord syndrome is moderate, with lower extremity function typically recovering before upper extremity function, though fine motor hand function may remain permanently impaired. Anterior cord syndrome results from ischemia or infarction of the anterior two-thirds of the spinal cord, typically due to anterior spinal artery occlusion. The clinical presentation includes motor paralysis below the level of the lesion from corticospinal tract damage and loss of pain and temperature sensation from spinothalamic tract involvement. Crucially, the dorsal columns are spared because they receive their blood supply from the posterior spinal arteries, resulting in preservation of proprioception, vibratory sense, and discriminative touch. This dissociation between preserved posterior column function and lost anterior cord function is the hallmark of anterior cord syndrome and distinguishes it from complete transection. The most common causes include aortic surgery, aortic dissection, atherosclerotic disease, and systemic hypotension. The prognosis for anterior cord syndrome is generally poor, as vascular injuries to the spinal cord are often irreversible. Panel A: Cross-sectional diagram of complete spinal cord transection showing all tracts disrupted, with a clinical timeline illustrating the progression from spinal shock with flaccid paralysis to upper motor neuron features over days to weeks. Panel B: Cross-sectional diagram of Brown-Sequard hemisection with color-coded arrows showing ipsilateral motor and proprioceptive loss and contralateral pain and temperature loss, accompanied by a dermatome map of the expected clinical findings. Panel C: Cross-sectional diagram of central cord syndrome highlighting the central damage pattern with somatotopic representation showing why upper extremity fibers are more affected than lower extremity fibers, alongside a clinical photograph of the typical hyperextension mechanism. Panel D: Cross-sectional diagram of anterior cord syndrome showing the territory of the anterior spinal artery shaded to indicate the affected area with preserved dorsal columns, accompanied by a vascular anatomy illustration showing the anterior spinal artery and common occlusion points. --- ### Section 3: Acute Spinal Cord Compression Acute spinal cord compression is a neurological emergency that demands rapid recognition and intervention to prevent irreversible paralysis. The most common cause is metastatic tumor, which accounts for the majority of cases and typically involves the epidural space through hematogenous spread to the vertebral body with subsequent posterior extension into the spinal canal. Other important causes include epidural abscess, traumatic fractures and dislocations, cervical spondylotic myelopathy when an acute insult is superimposed on chronic stenosis, and epidural hematoma, particularly in patients on anticoagulation. The thoracic spine is the most frequently affected region in metastatic cord compression, reflecting the large number of thoracic vertebral bodies and their rich vascular supply. The clinical presentation of acute spinal cord compression follows a recognizable sequence that should be familiar to every clinician. Back pain is frequently the earliest symptom and may precede neurological deficits by days to weeks; it is often localized to the level of compression and may be exacerbated by recumbency, coughing, or straining. Progressive weakness below the level of compression develops as the cord becomes increasingly compromised, and a sensory level, defined as the dermatomal level below which sensation is diminished or absent, is a key examination finding that helps localize the lesion. Bowel and bladder dysfunction, including urinary retention and fecal incontinence, are late manifestations that indicate severe cord compression and portend a worse prognosis. The tempo of progression varies from hours to days, and the neurological status at the time of definitive treatment is the strongest predictor of functional outcome. Emergency evaluation of suspected spinal cord compression begins with urgent MRI of the spine with gadolinium contrast, which is the imaging modality of choice for visualizing the spinal cord, epidural space, and surrounding structures. The imaging should cover the clinically suspected level plus at least one level above and below, and whole-spine imaging should be performed when metastatic disease is suspected because multiple levels of involvement are common. CT myelography is an acceptable alternative when MRI is contraindicated, such as in patients with non-compatible cardiac devices or severe claustrophobia. The neurological examination must be performed urgently and documented in detail, including motor strength in all major muscle groups, sensory level assessment, deep tendon reflexes, and assessment of rectal tone and perianal sensation, as this baseline examination guides subsequent treatment decisions and prognostication. Emergency management of acute spinal cord compression must be initiated as soon as the diagnosis is suspected, even before definitive imaging is obtained in cases of rapid deterioration. High-dose dexamethasone, typically administered as a 10 milligram intravenous bolus followed by 4 milligrams every 6 hours, reduces peritumoral edema and may provide temporary neurological improvement. Neurosurgical consultation should be obtained urgently for consideration of emergent decompressive surgery, which is indicated for tumors of unknown type, radioresistant histologies, spinal instability, or neurological deterioration during radiation. Radiation oncology consultation is essential for metastatic disease, as external beam radiation therapy is the primary treatment for radiosensitive tumors. Surgery should ideally be performed within 24 to 48 hours of the onset of neurological impairment, as outcomes are significantly better with earlier intervention, and patients who are ambulant at the time of treatment are far more likely to remain ambulant than those who are already paraplegic. Panel A: Sagittal MRI of the spine showing metastatic epidural compression with vertebral body involvement and posterior extension into the canal compressing the spinal cord, with annotations indicating the most common primary tumor sources. Panel B: Clinical progression diagram showing the sequential development of back pain, followed by radicular symptoms, motor weakness, sensory level, and finally bowel and bladder dysfunction with approximate timelines. Panel C: Comparison of MRI and CT myelography images of spinal cord compression demonstrating the strengths of each modality with indications for use. Panel D: Emergency management algorithm flowchart showing the parallel pathways of dexamethasone administration, urgent MRI, neurosurgical consultation, and radiation oncology referral with decision points for surgery versus radiation. --- ### Section 4: Spinal Cord Tumors Spinal cord tumors are classified by their anatomical relationship to the dura and spinal cord, which has important implications for tumor type, presentation, and surgical approach. Extradural tumors are the most common category and include metastases, lymphoma, and multiple myeloma, which typically arise in the vertebral bodies and extend into the epidural space. Intradural extramedullary tumors, which are located within the dura but outside the spinal cord itself, include meningiomas and schwannomas and are generally benign and amenable to surgical resection. Intramedullary tumors arise within the substance of the spinal cord and include ependymomas and astrocytomas; these are the most technically challenging to resect due to their intimate relationship with the neural tissue. Metastatic epidural spinal cord compression is the most common spinal cord tumor emergency and arises most frequently from primary malignancies of the lung, breast, prostate, kidney, and plasma cells in multiple myeloma. The thoracic spine is the most commonly affected level, followed by the lumbar and cervical regions. The clinical presentation typically follows a predictable progression beginning with localized back pain, which may have a mechanical or radicular quality, followed by progressive motor weakness, sensory changes including a sensory level, and finally bowel and bladder dysfunction. Treatment follows the emergency protocol described previously, combining high-dose corticosteroids with radiation therapy and, in selected cases, surgical decompression followed by radiation, which has been shown to be superior to radiation alone for patients with a single site of compression and a favorable prognosis. Primary spinal cord tumors encompass several distinct entities with different biological behaviors and treatment implications. Ependymoma is the most common intramedullary tumor in adults and typically arises in the central canal, often presenting with a well-defined cleavage plane that facilitates gross total resection. Astrocytomas of the spinal cord are infiltrative and lack a clear plane of dissection, making complete surgical removal difficult and recurrence common. Hemangioblastomas are highly vascular tumors associated with von Hippel-Lindau disease and require careful preoperative planning to manage intraoperative bleeding. Schwannomas are the most common intradural extramedullary tumors and characteristically produce a dumbbell-shaped mass that extends through the neural foramen. Meningiomas are the second most common intradural extramedullary tumors, are more frequent in women, and typically present as homogeneously enhancing masses on MRI. Treatment of spinal cord tumors depends on tumor type, location, grade, and the patient's neurological status. Surgery is the primary treatment for most primary spinal cord tumors, with the goal of maximal safe resection while preserving neurological function. Intraoperative neurophysiological monitoring with somatosensory and motor evoked potentials is essential for safe resection of intramedullary tumors. Radiation therapy is employed for metastatic disease, incompletely resected tumors, and malignant primary tumors. Chemotherapy plays a limited role in the treatment of spinal cord tumors compared to intracranial tumors. The neurological status at the time of treatment is the single most important prognostic factor, underscoring the importance of early diagnosis and intervention before irreversible neurological injury occurs. Panel A: Schematic cross-sectional and sagittal diagrams of the spine showing the three anatomical compartments of spinal tumors: extradural, intradural extramedullary, and intramedullary, with representative tumor types labeled for each location. Panel B: Sagittal MRI sequence showing metastatic epidural compression from breast cancer with vertebral body collapse and cord displacement, accompanied by a clinical progression timeline from pain to paralysis. Panel C: Gallery of sagittal MRI images of primary spinal cord tumors including a well-defined ependymoma with polar cysts, an infiltrative astrocytoma with cord expansion, a hemangioblastoma with flow voids, and a dumbbell-shaped schwannoma extending through the neural foramen. Panel D: Intraoperative photograph of spinal cord tumor resection with neurophysiological monitoring setup showing somatosensory and motor evoked potential tracings alongside a treatment decision algorithm based on tumor type and resectability. --- ### Section 5: Spinal Epidural Abscess Spinal epidural abscess is a life-threatening infection of the epidural space that can rapidly progress to irreversible spinal cord damage if not promptly recognized and treated. The most important risk factors include diabetes mellitus, which is present in a large proportion of cases, intravenous drug use, which provides a portal of entry for hematogenous bacterial seeding, and recent spinal procedures including epidural injections and spinal surgery. Immunocompromised states such as HIV infection and chronic corticosteroid use increase susceptibility, and a distant source of infection such as skin abscess, osteomyelitis, or endocarditis may serve as the nidus for hematogenous spread. Staphylococcus aureus is the causative organism in the majority of cases, including methicillin-resistant strains, making empiric coverage for MRSA essential. The clinical evolution of spinal epidural abscess follows a characteristic four-stage progression that should serve as a diagnostic framework. Stage 1 is characterized by back pain and fever, which may be the only presenting symptoms and are frequently misattributed to benign musculoskeletal causes, contributing to dangerous diagnostic delays. Stage 2 involves the development of radicular pain as the expanding abscess irritates adjacent nerve roots. Stage 3 marks the onset of motor and sensory deficits as the spinal cord or cauda equina becomes compressed. Stage 4 represents complete paralysis, which may be irreversible if decompression is not performed promptly. The classic clinical triad of fever, back pain, and neurological deficit is present in only 10 to 15 percent of patients at initial presentation, and clinicians must maintain a high index of suspicion, particularly in patients with known risk factors presenting with back pain and fever. Diagnosis of spinal epidural abscess requires a combination of imaging and laboratory studies. MRI of the spine with gadolinium contrast is the imaging study of choice and demonstrates a ring-enhancing epidural collection that displaces the thecal sac and may compress the spinal cord. The entire spine should be imaged, as multifocal abscesses are common. Blood cultures should be obtained before initiating antibiotics and are positive in approximately 60 percent of cases, potentially obviating the need for invasive tissue sampling. Inflammatory markers including white blood cell count, erythrocyte sedimentation rate, and C-reactive protein are characteristically elevated and serve both diagnostic and monitoring functions. If the diagnosis remains uncertain or a tissue sample is needed for culture-directed therapy, CT-guided aspiration of the collection can be performed. Treatment of spinal epidural abscess requires a dual approach combining intravenous antibiotics and, in most cases, surgical drainage. Empiric antibiotic therapy should be initiated immediately and typically consists of vancomycin to cover methicillin-resistant Staphylococcus aureus combined with a third-generation cephalosporin such as ceftriaxone for gram-negative coverage, with antibiotics subsequently tailored based on culture results. Urgent surgical drainage is indicated for patients with neurological deficits, neurological deterioration despite antibiotic therapy, or evidence of cord compression on imaging. Medical management alone, without surgery, may be considered in select patients without neurological deficits who demonstrate clinical and laboratory improvement on antibiotics, but close monitoring for any neurological change is mandatory. The total duration of antibiotic therapy is typically 4 to 6 weeks, guided by clinical response and serial inflammatory markers. Follow-up MRI is essential to monitor treatment response. Prognosis is directly related to the neurological status at the time of surgical intervention, with patients treated before the development of paralysis having far better outcomes. Panel A: Infographic displaying the major risk factors for spinal epidural abscess including diabetes mellitus, intravenous drug use, spinal procedures, immunosuppression, and distant infection sources with relative contribution data. Panel B: Four-panel clinical progression diagram illustrating stages 1 through 4 of spinal epidural abscess from back pain and fever through radicular pain to motor and sensory deficits and finally paralysis with typical timeframes for each stage. Panel C: Sagittal and axial MRI with gadolinium of a spinal epidural abscess showing the rim-enhancing collection compressing the thecal sac and spinal cord with annotations of key diagnostic features. Panel D: Treatment algorithm showing the parallel initiation of empiric antibiotics and surgical consultation with decision points for operative versus non-operative management based on neurological status and imaging findings. --- ### Section 6: Transverse Myelitis Transverse myelitis is an inflammatory disorder of the spinal cord that produces a clinical syndrome of motor weakness, a sensory level, and bladder dysfunction developing over hours to days. The etiology is diverse, and establishing the underlying cause is critical for guiding treatment and predicting long-term outcome. Idiopathic transverse myelitis accounts for approximately 30 to 40 percent of cases and is presumed to be a post-infectious or parainfectious immune-mediated process. Multiple sclerosis may present with transverse myelitis as its initial manifestation, and lesions in this context tend to be short segment, involving fewer than three vertebral segments, and partial in their cord involvement. Neuromyelitis optica spectrum disorder is characterized by longitudinally extensive transverse myelitis spanning three or more vertebral segments and is associated with aquaporin-4 antibodies. Other causes include viral infections, systemic autoimmune diseases such as systemic lupus erythematosus, Sjogren syndrome, and sarcoidosis. The clinical features of transverse myelitis reflect bilateral spinal cord dysfunction at the affected level. The onset is typically subacute, developing over hours to days, which distinguishes it from the hyperacute onset of vascular myelopathy and the insidious onset of compressive myelopathy. Motor weakness below the level of the lesion may range from mild paraparesis to complete paraplegia, and the distribution is usually bilateral and relatively symmetric, in contrast to the asymmetric pattern seen in Brown-Sequard syndrome. A sensory level is a hallmark finding and is defined as the dermatomal level below which sensation is diminished, including all modalities. Bladder dysfunction is typically early and prominent in transverse myelitis, in contrast to compressive myelopathy where bladder involvement tends to be a late finding, and its presence at presentation supports an inflammatory etiology. The diagnostic evaluation of transverse myelitis aims to confirm the diagnosis, determine the extent and characteristics of the cord lesion, and identify the underlying cause. MRI of the spine with gadolinium is the essential first step and demonstrates a T2-hyperintense lesion within the cord, with the length of the lesion being critically important: short-segment lesions favor multiple sclerosis while longitudinally extensive lesions spanning three or more segments suggest neuromyelitis optica spectrum disorder or MOG-associated disease. Cerebrospinal fluid analysis typically shows mild pleocytosis, elevated protein, and may reveal oligoclonal bands if multiple sclerosis is the underlying cause. Serum testing for aquaporin-4 antibodies and myelin oligodendrocyte glycoprotein antibodies is essential for identifying NMOSD and MOG-associated disease respectively. Brain MRI should be performed to evaluate for demyelinating lesions suggestive of multiple sclerosis. A comprehensive systemic workup including infectious serologies and autoimmune markers helps identify treatable underlying causes. Treatment of transverse myelitis follows a stepwise immunosuppressive approach. First-line therapy consists of intravenous methylprednisolone, typically administered at a dose of 1 gram daily for 3 to 5 consecutive days, which reduces inflammation and may hasten neurological recovery. Plasma exchange is employed as second-line therapy for patients who fail to improve with high-dose corticosteroids and is particularly effective in cases of severe or fulminant myelitis. When an underlying cause is identified, specific treatment of that condition is paramount, such as disease-modifying therapy for multiple sclerosis or long-term immunosuppression for NMOSD. The overall prognosis for transverse myelitis follows a rough rule of thirds: approximately one-third of patients make a good recovery with minimal residual deficits, one-third achieve a moderate recovery with persistent neurological impairment, and one-third experience poor recovery with severe residual disability including paraplegia and ongoing bladder dysfunction. Panel A: Etiological classification diagram of transverse myelitis showing idiopathic, multiple sclerosis-associated, NMOSD-associated, post-infectious, and autoimmune categories with relative proportions and distinguishing features. Panel B: Clinical examination findings composite showing bilateral lower extremity weakness testing, sensory level determination with dermatomal map, and bladder assessment with post-void residual measurement. Panel C: Side-by-side sagittal MRI comparisons showing a short-segment cord lesion characteristic of multiple sclerosis versus a longitudinally extensive lesion spanning more than three segments characteristic of NMOSD, with annotations of key distinguishing imaging features. Panel D: Stepwise treatment algorithm showing progression from intravenous methylprednisolone to plasma exchange to cause-specific therapy, with prognostic outcome distribution showing the rule of thirds for recovery. --- ### Section 7: Vascular Myelopathy Spinal cord infarction is a devastating vascular event that presents with the sudden onset of severe back pain followed by rapid development of neurological deficits. The anterior spinal artery syndrome is the most common pattern, producing motor paralysis and loss of pain and temperature sensation below the level of infarction while sparing proprioception and vibratory sense, which are supplied by the posterior spinal arteries. Risk factors for spinal cord infarction include aortic surgery, particularly procedures involving cross-clamping of the thoracic or abdominal aorta, aortic dissection, severe atherosclerotic disease of the aorta or segmental arteries, and systemic hypotension. MRI of the spine demonstrates characteristic infarction patterns including diffusion restriction on diffusion-weighted imaging and T2 hyperintensity, often in a pencil-like pattern in the anterior cord. Treatment is primarily supportive, as there is no established thrombolytic protocol for spinal cord infarction, and the prognosis is frequently poor with significant residual disability. Spinal arteriovenous malformations represent an important and treatable cause of progressive myelopathy. Spinal dural arteriovenous fistula is the most common type and occurs predominantly in middle-aged and older men, causing a progressive myelopathy through venous hypertension rather than hemorrhage. Intramedullary arteriovenous malformations are less common, tend to occur in younger patients, and carry a risk of hemorrhage presenting as acute myelopathy or subarachnoid hemorrhage. The presentation of dural arteriovenous fistulas is insidious and often mimics other causes of progressive myelopathy, with stepwise neurological deterioration that may worsen with physical activity due to exercise-induced increases in venous pressure. Diagnosis requires a high index of suspicion and is confirmed by spinal magnetic resonance angiography, which may demonstrate dilated perimedullary veins, followed by conventional spinal angiography, which remains the gold standard for definitive diagnosis and treatment planning. Spinal epidural hematoma is an acute emergency characterized by rapid-onset back pain and progressive neurological deterioration due to hemorrhage into the epidural space with resultant cord compression. The most common predisposing factors include anticoagulant therapy, coagulopathies, trauma, and invasive spinal procedures such as epidural anesthesia or lumbar puncture. The clinical presentation mirrors that of other causes of acute spinal cord compression, with sudden severe back pain followed by rapidly progressive weakness, sensory changes, and bowel and bladder dysfunction. MRI demonstrates a biconvex epidural collection that is hyperintense on T1-weighted imaging in the acute phase. Emergent surgical decompression through laminectomy and hematoma evacuation is the definitive treatment, and timing is critical, as neurological outcomes are significantly better when surgery is performed within 12 hours of symptom onset. Venous hypertensive myelopathy is a chronic, progressive condition caused by elevated venous pressure within the spinal cord, most commonly as a consequence of a spinal dural arteriovenous fistula. The fistula creates an abnormal connection between a dural artery and the coronal venous plexus, causing arterialization of the venous system with resultant venous congestion, cord edema, and ischemia. Patients present with gradually progressive myelopathy characterized by ascending weakness, sensory changes, and gait difficulty, often with symptoms that fluctuate and may worsen with physical activity or upright positioning. MRI demonstrates diffuse T2 hyperintensity within the cord, often spanning multiple segments, with prominent flow voids on the dorsal cord surface representing dilated perimedullary veins. The key to management is definitive treatment of the underlying fistula, which can be accomplished through endovascular embolization or surgical disconnection of the fistulous connection, and early treatment before irreversible cord damage has occurred is associated with the best outcomes. Panel A: Cross-sectional diagram of the spinal cord showing the territory of the anterior spinal artery syndrome with shaded areas of infarction alongside an axial MRI demonstrating characteristic owl's eye or snake's eye diffusion restriction pattern. Panel B: Spinal angiogram showing a dural arteriovenous fistula with arterialized perimedullary veins and an intramedullary arteriovenous malformation with nidus, alongside sagittal MRI showing flow voids along the dorsal cord surface. Panel C: Sagittal and axial MRI of an acute spinal epidural hematoma showing the biconvex hyperintense collection compressing the spinal cord with annotations of typical locations and causes. Panel D: Pathophysiological diagram of venous hypertensive myelopathy illustrating the dural fistula, arterialization of the venous system, venous congestion, cord edema, and clinical progression alongside corresponding MRI findings of diffuse T2 hyperintensity. --- ### Section 8: Cervical Spondylotic Myelopathy Cervical spondylotic myelopathy is the most common cause of spinal cord dysfunction in adults over the age of 55 and results from chronic compression of the cervical spinal cord by degenerative changes in the cervical spine. The pathological process involves multiple components including disc herniation and loss of disc height, formation of osteophytic spurs along the vertebral end plates and uncovertebral joints, hypertrophy and buckling of the ligamentum flavum, and, in some patients, ossification of the posterior longitudinal ligament. Congenital narrowing of the spinal canal predisposes to symptomatic myelopathy, as individuals with smaller canals have less reserve space to accommodate degenerative changes before the cord becomes compressed. The mechanism of cord injury involves both direct mechanical compression and chronic ischemia from compression of the intrinsic cord vasculature, leading to progressive demyelination and neuronal loss. The clinical presentation of cervical spondylotic myelopathy is characteristically insidious in onset and gradually progressive. Patients frequently complain of hand clumsiness and loss of fine motor dexterity, manifested as difficulty with buttons, handwriting, and handling small objects. Gait disturbance is another early and prominent feature, with patients developing a broad-based, spastic gait due to corticospinal tract involvement. Neck pain and stiffness are variable and may be surprisingly mild or even absent despite significant cord compression. Upper motor neuron signs are the hallmark examination findings and include hyperreflexia in the lower extremities, bilateral Babinski signs, increased muscle tone with spasticity, and clonus. Bladder dysfunction, typically manifesting as urinary urgency and frequency, is a late finding that indicates advanced disease. The neurological examination in cervical spondylotic myelopathy reveals several specific findings that aid in diagnosis and localization. The Lhermitte sign, an electric shock-like sensation radiating down the spine and into the extremities with neck flexion, indicates cervical cord irritation and, while not specific to spondylotic myelopathy, is frequently present. The Hoffman sign, elicited by flicking the distal phalanx of the middle finger and observing for involuntary flexion of the thumb and index finger, is a sensitive indicator of cervical myelopathy. Hyperreflexia in the lower extremities is expected due to upper motor neuron dysfunction, but the upper extremity reflexes may paradoxically be diminished if there is concurrent radiculopathy at the level of compression, creating a pattern of mixed upper and lower motor neuron findings. The myelopathy hand, characterized by the finger escape sign in which the ulnar digits drift into abduction and flexion when the hands are held outstretched, and impaired rapid grip-and-release testing, are specific indicators of cervical cord dysfunction. Management of cervical spondylotic myelopathy is guided by symptom severity, rate of progression, and imaging findings. Conservative management with observation, activity modification, and physical therapy may be appropriate for patients with mild and stable symptoms, though close clinical follow-up is essential because the natural history is one of gradual decline. Surgical decompression is indicated for moderate to severe myelopathy, progressive neurological deterioration, or MRI evidence of cord signal change, which indicates structural cord damage and portends poorer outcomes if left untreated. The surgical approach, whether anterior (discectomy and fusion or corpectomy) or posterior (laminoplasty or laminectomy with fusion), depends on the specific anatomy of compression, the number of levels involved, and cervical alignment. Prognosis after surgery is guarded, as surgery may stabilize the condition and prevent further decline, but the degree of improvement is less predictable and depends largely on the severity and duration of myelopathy prior to intervention. Panel A: Sagittal MRI of the cervical spine showing multilevel spondylotic changes with disc protrusion, osteophyte formation, ligamentum flavum hypertrophy, and resultant cord compression with intramedullary T2 signal change indicating myelopathy. Panel B: Clinical photographs demonstrating the gait abnormalities of cervical spondylotic myelopathy including broad-based spastic gait, and hand dysfunction showing the finger escape sign and impaired grip-and-release testing. Panel C: Composite illustration of key examination findings including Lhermitte sign testing with neck flexion, Hoffman sign elicitation technique, deep tendon reflex pattern showing mixed upper and lower motor neuron findings, and Babinski sign. Panel D: Surgical approach decision diagram comparing anterior cervical discectomy and fusion, corpectomy, and posterior laminoplasty with indications for each approach based on number of levels, location of compression, and cervical alignment. --- ### Section 9: Other Myelopathies Vitamin B12 deficiency causes subacute combined degeneration of the spinal cord, a condition in which the posterior columns and lateral corticospinal tracts undergo progressive demyelination and axonal loss. Patients present with a combination of sensory ataxia from posterior column dysfunction, manifested as impaired proprioception and vibratory sense with a positive Romberg sign, and upper motor neuron weakness from corticospinal tract involvement. The combination of posterior column sensory loss with hyperreflexia and extensor plantar responses is the clinical hallmark of subacute combined degeneration and reflects the simultaneous involvement of both the sensory and motor tracts. Laboratory diagnosis rests on demonstrating a low serum vitamin B12 level, along with elevated methylmalonic acid and homocysteine, which are more sensitive markers of functional B12 deficiency. MRI of the spine may show T2 hyperintensity in the posterior columns of the cervical and thoracic cord in an inverted V pattern. Treatment consists of B12 replacement, which may halt progression and lead to partial improvement, though established neurological damage may be permanent. Copper deficiency myelopathy is a nutritional myelopathy that closely mimics the clinical and pathological features of subacute combined degeneration from vitamin B12 deficiency. The most common causes include prior gastric surgery, particularly gastric bypass procedures that impair copper absorption, and excessive zinc supplementation, which competes with copper for intestinal absorption. The clinical presentation is indistinguishable from B12 deficiency myelopathy, with posterior column sensory loss, spastic paraparesis, and gait ataxia. Diagnosis requires demonstration of low serum copper and ceruloplasmin levels. Importantly, copper deficiency may coexist with hematological abnormalities including anemia and neutropenia, which may provide additional diagnostic clues. Treatment consists of copper supplementation, and removal of any precipitating factor such as zinc excess, though neurological recovery may be incomplete. HIV-associated myelopathy, also known as vacuolar myelopathy, is a progressive spinal cord disorder that occurs in patients with advanced HIV infection and low CD4 counts. The pathological hallmark is vacuolization of the myelin sheaths in the posterior and lateral columns of the thoracic cord, producing a clinical syndrome of progressive spastic paraparesis with posterior column sensory dysfunction. The presentation is insidious, with gradually worsening gait difficulty, leg stiffness, and urinary dysfunction. The diagnosis is one of exclusion, requiring the elimination of other causes of myelopathy in the HIV-infected patient including opportunistic infections such as cytomegalovirus, herpes viruses, and syphilis, as well as primary CNS lymphoma and HIV-associated inflammatory conditions. Treatment centers on effective antiretroviral therapy to suppress viral replication and restore immune function, though established neurological damage may not be reversible. Radiation myelopathy is a delayed complication of radiation therapy to the spine or adjacent structures and results from progressive demyelination and vascular injury within the irradiated spinal cord segments. The onset is typically months to years after radiation exposure, with a latency that inversely correlates with the radiation dose received. Patients develop a gradually progressive myelopathy with weakness, sensory changes, and bowel and bladder dysfunction corresponding to the irradiated cord levels. The risk of radiation myelopathy is dose-dependent, with the generally accepted tolerance of the spinal cord being approximately 45 Gray delivered in conventional fractionation, though individual susceptibility varies. MRI may demonstrate T2 signal change and enhancement within the irradiated cord segments. Treatment is primarily supportive, as there is no established curative therapy for radiation myelopathy, and prevention through careful radiation planning that respects cord tolerance limits remains the most important management strategy. Panel A: Axial MRI of the cervical spinal cord showing the characteristic inverted V pattern of T2 hyperintensity in the posterior columns in subacute combined degeneration from vitamin B12 deficiency, with a metabolic pathway diagram showing the role of B12 in methylmalonic acid and homocysteine metabolism. Panel B: Comparative diagram showing copper deficiency myelopathy alongside B12 deficiency with shared clinical features, common causes including gastric surgery and zinc excess, and diagnostic laboratory panels. Panel C: Histopathological illustration of HIV-associated vacuolar myelopathy showing vacuolization of myelin sheaths in the posterior and lateral columns with clinical correlation of progressive spastic paraparesis. Panel D: Radiation dose-response curve showing the relationship between spinal cord radiation dose and myelopathy risk, with sagittal MRI demonstrating radiation myelopathy at the irradiated level and a radiation treatment plan showing dose distribution relative to the spinal cord. --- ### Section 10: Conus Medullaris and Cauda Equina Syndromes The conus medullaris and cauda equina occupy the same spinal canal at the lumbosacral junction but represent anatomically and functionally distinct structures whose distinction is critical for accurate diagnosis and management. The conus medullaris is the tapered terminal end of the spinal cord itself, located at the level of the L1 to L2 vertebral bodies, and contains the sacral spinal cord segments that control bowel, bladder, and sexual function. Below the conus, the cauda equina consists of the lumbar and sacral nerve roots that continue to descend within the thecal sac before exiting through their respective neural foramina. Because the conus is spinal cord tissue, lesions at this level produce upper motor neuron signs, whereas the cauda equina consists of peripheral nerve roots and lesions produce lower motor neuron signs. This fundamental distinction has important implications for the clinical examination findings, prognosis, and urgency of treatment. The clinical comparison between conus medullaris and cauda equina syndromes reveals characteristic differences that aid in localization. Conus medullaris lesions typically produce symmetric motor deficits because the spinal cord segments are bilaterally organized, while cauda equina lesions tend to produce asymmetric weakness because individual nerve roots are selectively affected. Reflexes may be increased in conus lesions due to upper motor neuron involvement but are decreased or absent in cauda equina lesions. Saddle anesthesia, the loss of sensation in the perineal region corresponding to the S2 through S4 dermatomes, is present in both conditions but tends to be symmetric in conus lesions and asymmetric in cauda equina lesions. Bladder and sexual dysfunction develop early and are severe in conus lesions because the sacral cord segments directly control these functions, while in cauda equina syndrome these functions are affected later and more variably. Back pain tends to be more prominent in cauda equina syndrome due to nerve root irritation, while conus lesions may present with less pain. Cauda equina syndrome is a surgical emergency that requires emergent decompression to prevent permanent loss of bowel, bladder, and sexual function. The most common cause is a large central lumbar disc herniation, typically at the L4-L5 or L5-S1 level, but other causes include tumors, abscesses, epidural hematomas, and spinal stenosis. The cardinal red flag symptoms that should raise immediate suspicion include bilateral leg weakness, saddle anesthesia in the perineal region, urinary retention with overflow incontinence, and fecal incontinence. Any patient presenting with these features requires emergent MRI of the lumbar spine and neurosurgical consultation. Decompressive surgery, typically laminectomy with discectomy, should be performed as soon as possible, with evidence suggesting that outcomes are significantly better when surgery is completed within 48 hours of symptom onset, though earlier intervention remains preferable. The prognosis for both conus medullaris and cauda equina syndromes depends on several key factors. The timing of surgical intervention is the most important modifiable factor, with earlier decompression consistently associated with better neurological outcomes across all etiologies. Complete deficits at the time of presentation carry a worse prognosis than incomplete deficits, as the presence of residual neurological function indicates that viable but compromised neural tissue remains and may recover with decompression. Bladder function is particularly vulnerable and may not recover even with timely intervention if severely impaired at presentation, making urinary retention one of the most concerning prognostic features. The duration of symptoms prior to treatment also affects outcomes, with shorter symptom duration associated with better recovery. Patients with cauda equina syndrome from disc herniation generally have a more favorable prognosis than those with tumor or infection, as removal of the compressive disc allows the nerve roots to recover, while malignant or infectious processes may cause more permanent damage. Panel A: Sagittal anatomical diagram of the lumbosacral spine showing the conus medullaris terminating at L1-L2 and the cauda equina nerve roots descending below, with insets showing the upper motor neuron organization of the conus versus the lower motor neuron peripheral nerve root organization of the cauda equina. Panel B: Side-by-side clinical comparison diagram showing the differences between conus and cauda equina syndromes in terms of motor pattern, reflex changes, saddle anesthesia distribution, bladder involvement, and pain characteristics. Panel C: Sagittal MRI of cauda equina syndrome caused by a large central disc herniation at L4-L5 with compressed and displaced nerve roots, accompanied by clinical photographs of saddle anesthesia testing and urinary retention assessment. Panel D: Prognostic outcome chart showing the relationship between timing of surgical intervention and neurological recovery, with separate curves for complete versus incomplete deficits and bladder function recovery rates. --- ## Summary - Spinal cord anatomy follows a precise somatotopic organization: corticospinal tracts carry motor commands, dorsal columns transmit proprioception and vibration, and spinothalamic tracts convey pain and temperature - Brown-Sequard syndrome from cord hemisection produces ipsilateral motor and proprioceptive loss with contralateral pain and temperature loss - Central cord syndrome causes upper extremity weakness greater than lower extremity weakness, typically from hyperextension injury in cervical spondylosis - Anterior cord syndrome causes motor and pain/temperature loss with preserved proprioception, most commonly from anterior spinal artery infarction - Acute spinal cord compression requires urgent MRI, high-dose dexamethasone, and emergent neurosurgical consultation - Spinal epidural abscess presents with back pain, fever, and progressive neurological deficits and requires intravenous antibiotics and surgical drainage - Transverse myelitis produces bilateral weakness, sensory level, and early bladder dysfunction and is treated with intravenous methylprednisolone - Longitudinally extensive transverse myelitis spanning three or more segments should prompt evaluation for NMOSD with AQP4 and MOG antibody testing - Cervical spondylotic myelopathy is the most common cause of cord dysfunction in older adults, presenting with spastic gait and hand clumsiness - Cauda equina syndrome is a surgical emergency defined by saddle anesthesia, urinary retention, and bilateral leg weakness requiring decompression within 48 hours --- ## Key Terms | Term | Definition | |------|------------| | Myelopathy | Dysfunction of the spinal cord from any cause | | Sensory level | The dermatomal level below which sensation is diminished or absent | | Brown-Sequard syndrome | Hemisection of the spinal cord producing ipsilateral motor and proprioceptive loss with contralateral pain and temperature loss | | Conus medullaris | The tapered terminal end of the spinal cord located at the L1 to L2 vertebral level | | Cauda equina | The bundle of lumbar and sacral nerve roots descending below the conus medullaris | | Lhermitte sign | An electric shock-like sensation radiating down the spine with neck flexion indicating cervical cord pathology | | LETM | Longitudinally extensive transverse myelitis spanning three or more vertebral segments, associated with NMOSD | | Subacute combined degeneration | Demyelination of the posterior columns and lateral corticospinal tracts caused by vitamin B12 deficiency | --- *This content is subject to the [MIT License](https://opensource.org/licenses/MIT). © 2024–2026 Hibbert School of Medicine.*