# Clinical Cases: Sensory Systems ## Case 1: Syringomyelia - Dissociated Sensory Loss ### Patient Presentation **Demographics:** 35-year-old male **Chief Complaint:** Burns on hands that he did not feel occurring **History of Present Illness:** A 35-year-old construction worker presents after his wife noticed multiple burn marks on his hands that he was unaware of. He reports that over the past year, he has been unable to feel hot and cold temperatures in his hands and forearms. He has sustained several burns while cooking and working with hot materials without realizing it. He also reports neck pain and stiffness. Notably, he can still feel light touch and knows the position of his fingers. He denies weakness or gait problems. **Physical Examination:** - Vital signs: Normal - Neurological: - Mental status: Normal - Cranial nerves: Intact - Motor: 5/5 strength throughout; no atrophy; reflexes 2+ and symmetric - Sensory examination: - Pain and temperature: Absent in cape-like distribution (bilateral shoulders, arms, and hands to approximately T4 level) - Light touch: Intact throughout - Vibration and proprioception: Intact throughout - Gait: Normal **Workup:** - **MRI cervical and thoracic spine with and without contrast:** Syrinx (fluid-filled cavity) extending from C4 to T2 within the central spinal cord; Chiari I malformation with 8 mm cerebellar tonsillar herniation below the foramen magnum - **Brain MRI:** Chiari I malformation confirmed; no hydrocephalus **Diagnosis:** Syringomyelia secondary to Chiari I malformation **Treatment:** - Neurosurgical consultation for Chiari decompression surgery - Posterior fossa decompression with duraplasty performed - Post-operative MRI at 6 months showed reduction in syrinx size - Occupational therapy for sensory protection strategies - Education on avoiding burns and injuries due to sensory loss **Clinical Pearl:** Syringomyelia causes the classic "dissociated sensory loss" pattern because the syrinx cavity disrupts the crossing spinothalamic fibers in the anterior white commissure while sparing the posterior columns. The spinothalamic tract carries pain and temperature sensation, which crosses at the level of entry. Thus, patients lose pain and temperature sensation at the level of the syrinx while retaining light touch, vibration, and proprioception (carried by the intact posterior columns). The cape-like distribution reflects the cervical location of the syrinx affecting crossing fibers at those levels. --- ## Case 2: Brown-Sequard Syndrome - Spinal Cord Hemisection ### Patient Presentation **Demographics:** 28-year-old male **Chief Complaint:** Weakness of left leg and numbness of right leg after a stabbing injury **History of Present Illness:** A 28-year-old man is brought to the emergency department after being stabbed in the back during an altercation. He immediately developed weakness in his left leg and was unable to walk. He also reports numbness in his right leg and "strange sensations" in his left leg. He denies any loss of consciousness or head trauma. **Physical Examination:** - Vital signs: BP 128/78, HR 92, RR 16 - Trauma assessment: 3 cm stab wound over left paravertebral region at approximately T8 level; hemodynamically stable - Neurological: - Mental status: Alert, oriented, appropriate - Cranial nerves: Intact - Motor: Left lower extremity 2/5 throughout; right lower extremity 5/5; upper extremities normal - Sensory examination: - Left side: Loss of vibration sense and proprioception from T8 down; pain and temperature intact - Right side: Loss of pain and temperature from T10 down (two levels below lesion); light touch and proprioception intact - Reflexes: Left lower extremity hyperreflexic (3+) with upgoing Babinski; right lower extremity normal (2+) - Rectal tone: Present **Workup:** - **CT spine:** Bony structures intact - **MRI thoracic spine:** Left hemicord injury at T8 level with cord edema and small hematoma - **CT chest/abdomen:** No visceral injury **Diagnosis:** Brown-Sequard syndrome (spinal cord hemisection) at T8 level due to penetrating trauma **Treatment:** - Spinal precautions maintained - Neurosurgical consultation; no surgical intervention indicated as spinal cord injury is complete at the hemi-cord level - High-dose methylprednisolone controversial and not administered in this case - DVT prophylaxis (penetrating injury) - Aggressive physical therapy and rehabilitation - Significant motor recovery expected given hemisection pattern **Clinical Pearl:** Brown-Sequard syndrome demonstrates the anatomical organization of spinal cord tracts. Hemisection causes ipsilateral motor weakness (corticospinal tract), ipsilateral loss of vibration and proprioception (posterior columns), and contralateral loss of pain and temperature (spinothalamic tract, which crosses 1-2 levels above the entry point). Brown-Sequard syndrome has the best prognosis among incomplete spinal cord injuries, with most patients regaining ambulatory function because the contralateral corticospinal tract is preserved. --- ## Case 3: Trigeminal Neuralgia ### Patient Presentation **Demographics:** 62-year-old female **Chief Complaint:** Severe, shooting facial pain for 3 months **History of Present Illness:** A 62-year-old woman presents with recurrent episodes of excruciating, electric shock-like pain on the right side of her face. The pain episodes are brief (seconds to less than 2 minutes) but occur multiple times daily. The pain is triggered by brushing her teeth, eating, talking, or even a light breeze on her face. She has identified a "trigger zone" on her right cheek that, when touched, precipitates an attack. Between attacks, she is pain-free. She has lost 10 pounds because she is afraid to eat. The pain has not responded to over-the-counter pain medications. **Physical Examination:** - Vital signs: Normal - General: Appears anxious; avoids touching right side of face - Neurological: - Mental status: Normal - Cranial nerves: Cranial nerve V examination completely normal (no sensory loss, normal corneal reflex, normal motor function); all other cranial nerves intact - Motor, sensory, reflexes: Normal - Dental examination: No dental pathology identified **Workup:** - **MRI brain with high-resolution constructive interference in steady state (CISS) sequence:** Vascular loop (superior cerebellar artery) contacting and compressing the right trigeminal nerve root entry zone; no mass lesions or demyelinating plaques - **Routine blood work:** Normal **Diagnosis:** Classic trigeminal neuralgia (tic douloureux) due to neurovascular compression **Treatment:** - Carbamazepine 100 mg twice daily initiated, titrated to 400 mg twice daily with good pain control - CBC and liver function monitored (carbamazepine side effects) - HLA-B*1502 testing performed before carbamazepine initiation (Asian ancestry screening for Stevens-Johnson syndrome risk) - Education that surgical options (microvascular decompression, gamma knife radiosurgery) available if medication fails or intolerable - Pain-free on carbamazepine at 6-month follow-up **Clinical Pearl:** Trigeminal neuralgia is characterized by brief, severe, stereotyped pain attacks in the distribution of one or more trigeminal nerve divisions. The mandibular (V3) and maxillary (V2) divisions are most commonly affected, often with a trigger zone. Classic trigeminal neuralgia results from neurovascular compression of the trigeminal nerve root, most commonly by the superior cerebellar artery. Importantly, the neurological examination is NORMAL between attacks in classic cases. Sensory loss, young age, or bilateral symptoms suggest secondary causes such as multiple sclerosis or tumor and warrant thorough investigation. --- ## Clinical Image ![Syringomyelia MRI](case_01_image.jpg) **Image Description:** Sagittal T2-weighted MRI of the cervical spine demonstrating a syrinx (hyperintense fluid-filled cavity) within the central spinal cord, along with Chiari I malformation showing cerebellar tonsillar herniation below the foramen magnum. **Attribution:** Image from Radiopaedia (https://radiopaedia.org/), Creative Commons Attribution-NonCommercial-ShareAlike 3.0 license.