# Seminar 14: Pediatric Neurology ## Neurology Clerkship --- ## Learning Objectives By the end of this seminar, students will be able to: 1. Assess neurological development in children 2. Recognize developmental delay and regression 3. Diagnose common pediatric neurological conditions 4. Evaluate and manage childhood epilepsy syndromes 5. Identify neuromuscular disorders in children 6. Recognize neurogenetic and metabolic disorders --- ## Seminar Outline ### Section 1: Pediatric Neurological Examination The assessment of developmental milestones is the foundation of the pediatric neurological examination and provides the earliest indication of neurological health or dysfunction. By 2 months of age, an infant should be able to lift the head while in the prone position, the hands should be predominantly unfisted, vocalizations should include cooing, and the social smile should have emerged. By 4 months, the infant can roll over, reaches for objects, laughs aloud, and responds to familiar faces. At 6 months, the child sits with support, transfers objects between hands, produces babbling consonant-vowel combinations, and begins to show stranger anxiety. By 9 months, crawling has developed, the pincer grasp emerges, the child produces nonspecific "mama" and "dada" vocalizations, and social gestures such as waving bye-bye appear. At 12 months, the child walks with support, can voluntarily release objects, uses one to two specific words, and follows simple commands. By 18 months, independent walking is established, the child can stack two to four blocks, expressive vocabulary has grown to 10 to 25 words, and pointing to desired objects emerges as a communicative gesture. At 24 months, the child runs, stacks six blocks, combines two words into short phrases, and engages in parallel play alongside other children. The recognition of developmental red flags enables early identification of children who require urgent neurological evaluation. The absence of a social smile by 3 months of age raises concern for global developmental delay, as this milestone reflects the integration of visual, social, and cortical function. Failure to sit independently by 9 months suggests motor delay that may indicate cerebral palsy, neuromuscular disease, or other motor pathway pathology. The absence of any words by 16 months warrants evaluation for language delay, which may reflect hearing loss, autism spectrum disorder, or intellectual disability. Loss of previously acquired milestones, known as regression, demands urgent evaluation because it may signal a progressive neurodegenerative or metabolic disorder. Asymmetric movement patterns, such as a preference for one hand before 12 months of age, should raise suspicion for contralateral hemiparesis. The combination of hypotonia with weakness points toward a neuromuscular etiology and should prompt evaluation for conditions such as spinal muscular atrophy or congenital myopathy. Primitive reflexes are brainstem-mediated responses that are present in healthy newborns and disappear at predictable ages as cortical maturation progresses and higher-level motor control emerges. The Moro reflex, present from birth, consists of abduction and extension of the arms followed by adduction in response to a sudden head drop, and normally disappears between 3 and 6 months. The grasp reflex, in which firm pressure on the palm elicits finger flexion, is present from birth and disappears between 4 and 6 months. The rooting reflex, triggered by stroking the cheek and causing the infant to turn toward the stimulus, is present from birth and disappears by 3 to 4 months. The asymmetric tonic neck reflex, in which turning the head causes extension of the ipsilateral arm and flexion of the contralateral arm in a fencing posture, is present from birth and disappears between 6 and 7 months. The stepping reflex, in which the infant makes walking movements when held upright with feet touching a surface, is present from birth and disappears by 2 months. The parachute reflex is unique in that it appears later, at approximately 8 to 9 months, when the infant extends the arms protectively when tilted forward, and persists throughout life as a normal protective response. The approach to the neurological examination must be adapted to the child's developmental stage, as the standard adult neurological examination cannot be directly applied to young children. In infants, the examination relies heavily on observation of spontaneous movements, posture, and responses to handling, with gentle manipulation to assess tone and elicit primitive reflexes. In toddlers, a play-based approach is most effective, incorporating toys and games to observe motor skills, coordination, and cognitive function while using distraction techniques to reduce anxiety and improve cooperation. School-age children can participate in a more formalized examination, though instructions should be communicated in simple, age-appropriate language. Adolescents can undergo an essentially adult-style examination, with attention to providing appropriate privacy and confidentiality. Pediatric neuro exam: milestones, red flags, primitive reflexes, approach --- ### Section 2: Developmental Delay and Intellectual Disability Developmental delay and intellectual disability are classified based on the child's age and the pattern of domains affected. Global developmental delay is the term used for children under 5 years of age who demonstrate significant delays in two or more developmental domains, including gross motor, fine motor, speech and language, cognitive, and social or adaptive function. Intellectual disability is the diagnosis applied to children aged 5 years and older who demonstrate an IQ below 70 on standardized testing in conjunction with deficits in adaptive functioning, such as self-care, communication, and social skills. Specific developmental delay refers to delay in a single domain, such as isolated motor delay or isolated language delay, and often has a more focused differential diagnosis and evaluation. The causes of developmental delay are numerous and span prenatal, perinatal, and postnatal categories, though a significant proportion remain unexplained despite thorough evaluation. Genetic causes are the most commonly identified etiology and include chromosomal abnormalities such as Down syndrome, single-gene disorders such as fragile X syndrome and Rett syndrome, and copy number variants detected by chromosomal microarray. Congenital causes include structural brain malformations and congenital infections such as those in the TORCH complex. Perinatal causes include hypoxic-ischemic encephalopathy from birth asphyxia, complications of prematurity including periventricular leukomalacia, and kernicterus from severe neonatal hyperbilirubinemia. Postnatal causes include traumatic brain injury, central nervous system infections, and exposure to toxins such as lead. Metabolic causes include phenylketonuria and congenital hypothyroidism, both of which are included in newborn screening programs because early detection and treatment can prevent or substantially mitigate intellectual disability. Despite thorough evaluation, approximately 30 percent of cases remain idiopathic with no identifiable underlying cause. The evaluation of a child with developmental delay follows a systematic, tiered approach guided by the clinical presentation and associated features. Genetic testing, typically beginning with chromosomal microarray and fragile X testing, is recommended as a first-line investigation for most children with unexplained global developmental delay. Metabolic testing is indicated when the clinical presentation includes regression, specific dysmorphic features, or other findings suggestive of an inborn error of metabolism. Brain MRI is performed to evaluate for structural abnormalities including malformations of cortical development, white matter abnormalities, and evidence of prior injury. Electroencephalography is indicated when seizures are suspected based on the history or clinical examination. Hearing and vision assessment should be performed in all children with developmental delay, as sensory deficits can mimic or contribute to apparent cognitive and language delays and are readily treatable. Autism spectrum disorder is a neurodevelopmental condition defined by two core domains of impairment: deficits in social communication and social interaction, and restricted, repetitive patterns of behavior, interests, or activities. Symptoms are characteristically present before age 3, although the diagnosis may not be made until later if symptoms are mild or if the child's abilities mask the underlying deficits. Screening for autism spectrum disorder is recommended at 18 and 24 months of age using the Modified Checklist for Autism in Toddlers, or M-CHAT. Autism spectrum disorder is associated with several neurological comorbidities, with epilepsy occurring in 20 to 30 percent of affected individuals and intellectual disability in approximately 30 percent, and various genetic syndromes including fragile X and tuberous sclerosis carry an elevated risk of autism. The cornerstone of intervention is early intensive behavioral therapy, particularly applied behavior analysis, which has been shown to improve outcomes in social communication, adaptive behavior, and cognitive function when initiated at a young age. Developmental delay: classification, causes, evaluation, autism --- ### Section 3: Cerebral Palsy Cerebral palsy is defined as a non-progressive motor disorder resulting from injury to the developing brain that occurs during the prenatal, perinatal, or early postnatal period. Although the brain injury itself is static and non-progressive, the motor manifestations evolve as the child grows and the developing nervous system matures, and the condition is frequently accompanied by associated impairments in sensation, cognition, communication, perception, and behavior. The clinical presentation is heterogeneous and depends on the timing, location, and extent of the brain injury, ranging from mild clumsiness in one limb to severe quadriplegia with minimal voluntary movement. Cerebral palsy is classified by the predominant type of motor abnormality, which reflects the location of the brain injury. Spastic cerebral palsy is the most common type and is characterized by increased muscle tone, hyperreflexia, and an upper motor neuron pattern of weakness, resulting from injury to the cerebral cortex or pyramidal tracts. Dyskinetic cerebral palsy is characterized by involuntary movements including dystonia, chorea, and athetosis, and typically results from injury to the basal ganglia, as may occur with severe neonatal hyperbilirubinemia (kernicterus) or acute hypoxic injury to the deep gray matter structures. Ataxic cerebral palsy presents with incoordination, hypotonia, and impaired balance, reflecting cerebellar injury. Mixed cerebral palsy involves a combination of motor types and indicates injury to multiple brain regions. The topographic distribution of motor involvement provides additional classification and often correlates with the etiology of the brain injury. Hemiplegia, affecting one side of the body, is the most common pattern in term infants and typically results from a unilateral cerebral injury such as perinatal stroke. Diplegia, in which the legs are affected more severely than the arms, is the pattern most commonly associated with prematurity and periventricular white matter injury. Quadriplegia, involving all four limbs, represents the most severe form and is associated with extensive bilateral brain injury. Monoplegia, affecting a single limb, is rare and should prompt consideration of alternative diagnoses such as brachial plexus injury. The management of cerebral palsy requires a comprehensive, multidisciplinary approach addressing the diverse needs of the child across multiple domains. Physical therapy focuses on stretching to prevent contractures, strengthening exercises, and training in mobility skills including gait and wheelchair use. Occupational therapy addresses activities of daily living, fine motor skills, and upper extremity function. Spasticity management employs a range of interventions including oral medications such as baclofen, chemodenervation with botulinum toxin for focal spasticity, and intrathecal baclofen pump placement for severe generalized spasticity. Orthopedic management includes bracing to support alignment and function, and surgical intervention for fixed contractures and skeletal deformities. Seizures, which occur in a significant proportion of children with cerebral palsy, are managed with antiepileptic medications. Communication deficits are addressed through speech therapy and, when verbal communication is not achievable, through augmentative and alternative communication devices. Cerebral palsy: definition, motor types, topography, management --- ### Section 4: Pediatric Epilepsy Syndromes Infantile spasms, also known as West syndrome, is one of the most important epilepsy syndromes of infancy and represents a neurological emergency requiring prompt diagnosis and treatment. The typical age of onset is between 3 and 12 months, with a peak around 4 to 6 months. The seizures consist of clusters of brief flexor or extensor spasms, often occurring in series upon awakening, with each spasm lasting only one to two seconds but the clusters continuing for several minutes. The EEG demonstrates the characteristic pattern of hypsarrhythmia, a chaotic, disorganized pattern of high-amplitude slow waves with superimposed multifocal sharp waves and spikes that is virtually diagnostic of the syndrome. The underlying causes are diverse and include tuberous sclerosis complex, hypoxic-ischemic encephalopathy, structural brain malformations, and genetic disorders. Treatment relies on ACTH (adrenocorticotropic hormone) as the standard first-line agent, with vigabatrin being particularly effective when the underlying etiology is tuberous sclerosis complex. The prognosis is often poor, with a significant proportion of children developing intellectual disability and evolving into other seizure types, including Lennox-Gastaut syndrome. Childhood absence epilepsy is the prototypical generalized epilepsy of childhood and is characterized by frequent, brief episodes of staring and unresponsiveness. The typical age of onset is between 4 and 10 years, with a slight female predominance. The seizures manifest as abrupt-onset staring spells lasting 5 to 30 seconds, during which the child is unresponsive and may exhibit subtle automatisms such as eye blinking or lip smacking; episodes may occur dozens to hundreds of times per day and often go unrecognized by parents and teachers, being attributed to inattention or daydreaming. The EEG demonstrates the pathognomonic pattern of generalized 3 Hz spike-and-wave discharges, which can be reliably provoked by hyperventilation during the EEG recording. Treatment options include ethosuximide, valproate, and lamotrigine, with ethosuximide and valproate demonstrating the highest efficacy in clinical trials. The prognosis is generally favorable, with approximately 70 percent of patients achieving seizure remission by adolescence. Benign epilepsy with centrotemporal spikes, or BECTS, is the most common focal epilepsy syndrome of childhood and follows a reliably benign course. The typical age of onset is between 3 and 13 years. The seizures are focal motor in nature, characteristically involving the face and arm with tingling and twitching of the perioral region that may spread to the ipsilateral hand, and they occur predominantly during sleep or at the transition between sleep and wakefulness. The EEG demonstrates characteristic high-amplitude centrotemporal spikes that are often activated by sleep. Many children with BECTS do not require antiepileptic medication because the seizures are infrequent and nocturnal, but when treatment is indicated, levetiracetam is a commonly used option. The prognosis is excellent, with virtually all patients achieving complete seizure remission by age 15 as the brain matures. Lennox-Gastaut syndrome is a severe epileptic encephalopathy of childhood that carries a poor prognosis for both seizure control and cognitive development. The onset typically occurs between 1 and 8 years of age, and the syndrome may evolve from prior infantile spasms. The hallmark of Lennox-Gastaut syndrome is the occurrence of multiple seizure types in the same patient, including tonic seizures, atonic seizures producing sudden drop attacks, and atypical absence seizures with gradual onset and offset. The EEG demonstrates a generalized slow spike-and-wave pattern at a frequency less than 2.5 Hz, which distinguishes it from the faster 3 Hz pattern of childhood absence epilepsy. Treatment is challenging and often requires polytherapy, with valproate, lamotrigine, rufinamide, and clobazam being among the most commonly used agents, though seizure control is rarely achieved completely. The prognosis is poor, with most patients experiencing refractory seizures, progressive intellectual disability, and significant lifelong disability. Pediatric epilepsy: infantile spasms, absence, BECTS, Lennox-Gastaut --- ### Section 5: Febrile Seizures Febrile seizures are classified into simple and complex categories based on their clinical characteristics, and this distinction has important implications for evaluation and prognosis. Simple febrile seizures are generalized in onset, last less than 15 minutes, and do not recur within a 24-hour period. Complex febrile seizures are defined by the presence of any one of three features: focal onset suggesting a localized cerebral origin, duration exceeding 15 minutes, or recurrence within the same 24-hour febrile illness. Febrile seizures are the most common seizure type in childhood, occurring in 2 to 5 percent of children between the ages of 6 months and 5 years, with a peak incidence at 12 to 18 months. A positive family history of febrile seizures is frequently present, reflecting a genetic predisposition to seizures in the setting of fever. The seizures occur during febrile illnesses and are thought to reflect the heightened susceptibility of the immature brain to the effects of rapidly rising body temperature. The evaluation of a child with a febrile seizure is guided by the classification and the overall clinical presentation. For a simple febrile seizure in a well-appearing child, no routine laboratory testing, EEG, or neuroimaging is indicated, as the yield of these investigations is extremely low in this context. Lumbar puncture should be performed if meningitis is clinically suspected based on the presence of meningeal signs, toxic appearance, or a prolonged postictal state, and should be strongly considered in infants under 12 months of age in whom the clinical signs of meningitis may be subtle or absent. EEG is not indicated for simple febrile seizures, as it does not predict the development of epilepsy. MRI brain imaging is similarly not indicated for simple febrile seizures. The prognosis after febrile seizures is generally reassuring, though parents often require significant counseling and education. The risk of recurrence is approximately 30 to 35 percent, with the highest risk in children who experience their first febrile seizure at a young age and those with a positive family history. The risk of subsequently developing epilepsy is approximately 2 to 4 percent, compared with 1 percent in the general population, and this risk is somewhat higher in children with complex febrile seizures. Management consists primarily of treating the underlying febrile illness and providing thorough parent education about the benign nature of the condition and appropriate first-aid measures. Prophylactic antiepileptic medication is not routinely recommended given the benign prognosis. Rectal diazepam is available as a rescue medication for children who experience prolonged febrile seizures exceeding five minutes. Febrile seizures: simple vs complex, evaluation, prognosis --- ### Section 6: Pediatric Headache Migraine in children shares the fundamental pathophysiology of adult migraine but has several distinguishing clinical features that the clinician must recognize to avoid underdiagnosis. The duration of migraine attacks in children is shorter than in adults, lasting 1 to 72 hours compared with the 4 to 72 hours required for the adult diagnostic criteria. The headache location in children is often bilateral, in contrast to the predominantly unilateral pattern seen in adults. Associated features include nausea, photophobia, phonophobia, and pallor, the latter being a particularly common feature in childhood migraine. Common triggers include disrupted sleep patterns, emotional stress, specific foods, and dehydration. Treatment of acute attacks relies on ibuprofen as the first-line analgesic, and triptans are approved for use in children over 6 years of age for moderate to severe attacks that do not respond to simple analgesics. The childhood periodic syndromes are a group of episodic disorders that are considered precursors to migraine and are classified as migraine equivalents in the pediatric headache literature. Cyclic vomiting syndrome presents with recurrent, stereotyped episodes of intense nausea and vomiting that last hours to days and are separated by symptom-free intervals. Abdominal migraine causes recurrent episodes of midline abdominal pain accompanied by nausea, vomiting, and pallor. Benign paroxysmal vertigo of childhood presents with brief, self-limited episodes of vertigo occurring without warning in otherwise well children. These syndromes share the common feature that affected children often evolve into typical migraine headaches as they reach adolescence and adulthood, supporting their classification within the migraine spectrum. Several red flags in the headache history should prompt urgent evaluation for secondary causes of headache in children. Headache that awakens the child from sleep raises concern for elevated intracranial pressure from a mass lesion or hydrocephalus. Headache that worsens with Valsalva maneuvers such as coughing, straining, or bearing down suggests a posterior fossa lesion. A progressive headache pattern, increasing in frequency or severity over weeks to months, raises concern for an expanding mass lesion. The presence of focal neurological signs on examination indicates a structural etiology. Personality or behavioral changes may be the presenting feature of a frontal lobe tumor. Children under 5 years of age with new-onset headache warrant a higher index of suspicion for secondary causes, as primary headache disorders are less common in this age group. Secondary headaches in children encompass several important diagnoses that must be distinguished from primary headache disorders. Brain tumors typically present with progressive headache that is worse in the morning upon awakening, is associated with nausea and vomiting, and may be accompanied by evolving neurological deficits. Hydrocephalus presents with morning headache, vomiting, and in younger children with open sutures, an increasing head circumference. Pseudotumor cerebri, or idiopathic intracranial hypertension, most commonly affects obese adolescent females and presents with headache and papilledema on fundoscopic examination. Chiari malformation type I presents with occipital headache that characteristically worsens with straining, coughing, and physical exertion. Pediatric headache: migraine, periodic syndromes, red flags, secondary causes --- ### Section 7: Pediatric Neuromuscular Disorders Duchenne muscular dystrophy is the most common and most severe of the childhood muscular dystrophies, caused by mutations in the dystrophin gene on the X chromosome that result in absence of the dystrophin protein. The inheritance is X-linked recessive, and the disorder therefore almost exclusively affects boys, with an onset of symptoms typically between 2 and 5 years of age. The clinical presentation is characterized by progressive proximal muscle weakness, manifested by difficulty running, climbing stairs, and rising from the floor, the last of which produces the classic Gower's sign in which the child uses the hands to walk up the legs to compensate for hip extensor weakness. Calf pseudohypertrophy, in which the calves appear enlarged due to replacement of muscle tissue with fibrotic and fatty tissue, is a characteristic physical finding. Serum creatine kinase levels are markedly elevated, often in the tens of thousands, reflecting ongoing muscle fiber destruction. Cardiomyopathy develops in virtually all patients and is a major cause of morbidity and mortality. Management includes corticosteroids, which have been shown to slow the progression of weakness and prolong ambulation, along with regular cardiac monitoring and physical therapy to maintain range of motion and function. The natural history involves progressive weakness leading to wheelchair dependence by the early teenage years, with death typically resulting from cardiac or respiratory failure. Spinal muscular atrophy is a group of autosomal recessive neuromuscular disorders caused by homozygous deletion or mutation of the SMN1 gene, which encodes the survival motor neuron protein essential for the maintenance of lower motor neurons. Type 1, also known as Werdnig-Hoffmann disease, is the most severe form, with onset before 6 months of age and presentation as severe hypotonia and weakness; affected infants never achieve the ability to sit independently and typically succumb to respiratory failure in the first two years of life without treatment. Type 2 presents between 6 and 18 months of age, and children achieve the ability to sit but never walk independently. Type 3, also known as Kugelberg-Welander disease, has onset after 18 months of age, and affected individuals achieve independent walking, though with slowly progressive proximal weakness. The treatment landscape for spinal muscular atrophy has been transformed by the development of disease-modifying therapies, including nusinersen, an antisense oligonucleotide administered intrathecally that modifies splicing of the SMN2 gene to increase production of functional survival motor neuron protein; onasemnogene abeparvovec, a gene therapy delivered by a single intravenous infusion that provides a functional copy of the SMN1 gene; and risdiplam, an oral small molecule that similarly modifies SMN2 splicing. Congenital myopathies are a heterogeneous group of genetic muscle disorders that typically present in the neonatal period or early infancy with hypotonia and weakness. Central core disease is characterized by hypotonia, proximal weakness, and is importantly associated with a risk of malignant hyperthermia during general anesthesia, making recognition of this diagnosis essential for perioperative safety. Nemaline myopathy presents with hypotonia and weakness along with distinctive craniofacial features including an elongated face and high-arched palate. Myotubular myopathy is an X-linked condition that presents with severe neonatal hypotonia and respiratory insufficiency. Diagnosis of the congenital myopathies relies on muscle biopsy, which reveals characteristic structural abnormalities specific to each type, and increasingly on genetic testing, which can often establish the diagnosis non-invasively. Congenital myasthenic syndromes are a group of genetic disorders affecting neuromuscular junction transmission that must be distinguished from the more common autoimmune myasthenia gravis. Multiple genetic forms have been identified, affecting presynaptic, synaptic, and postsynaptic components of the neuromuscular junction. The clinical presentation includes ptosis, extraocular muscle weakness, generalized muscle weakness, and feeding difficulties, with onset typically in infancy or early childhood. An important distinction must be drawn between congenital myasthenic syndromes, which are genetic and permanent, and transient neonatal myasthenia gravis, which occurs in infants born to mothers with autoimmune myasthenia gravis due to transplacental transfer of acetylcholine receptor antibodies and resolves spontaneously as the maternal antibodies are cleared. Treatment of congenital myasthenic syndromes depends on the specific genetic type, with pyridostigmine and 3,4-diaminopyridine being among the most commonly used agents. Pediatric neuromuscular: DMD, SMA, congenital myopathies and myasthenia --- ### Section 8: Neurodevelopmental Regression Neurodevelopmental regression, the loss of previously acquired developmental skills, is one of the most alarming clinical scenarios in pediatric neurology and always demands urgent evaluation. Loss of milestones in any domain is the defining feature and should immediately trigger a comprehensive workup. Loss of language skills may indicate autism spectrum disorder, which characteristically involves regression in social and communicative function during the second year of life, or a neurodegenerative process. Loss of motor skills raises strong suspicion for storage diseases or leukodystrophies that progressively damage the nervous system. The combination of regression with seizures suggests a progressive myoclonic epilepsy syndrome. Cognitive decline, particularly when accompanied by multi-system involvement, raises concern for mitochondrial disease, lysosomal storage disorders, or inflammatory conditions affecting the brain. The metabolic storage diseases represent an important group of causes of neurodevelopmental regression, each with characteristic clinical features. Tay-Sachs disease, caused by hexosaminidase A deficiency, presents with infantile regression, progressive neurological deterioration, and the classic cherry-red spot on fundoscopic examination of the macula. Metachromatic leukodystrophy is a white matter disease caused by arylsulfatase A deficiency that presents with progressive motor and cognitive regression accompanied by peripheral neuropathy. Krabbe disease presents with irritability and progressive spasticity in infancy, caused by galactocerebroside beta-galactosidase deficiency leading to central and peripheral demyelination. Niemann-Pick disease type C is characterized by the distinctive finding of vertical supranuclear gaze palsy in combination with progressive ataxia and cognitive decline. The mucopolysaccharidoses are a group of lysosomal storage disorders that present with coarse facial features, organomegaly, skeletal abnormalities, and progressive neurological decline. Mitochondrial diseases are a diverse group of disorders resulting from dysfunction of the mitochondrial respiratory chain and can affect virtually any organ system, with the nervous system and muscle being particularly vulnerable due to their high metabolic demands. MELAS, which stands for mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes, presents with recurrent stroke-like episodes that do not conform to vascular territories, seizures, and persistent lactic acidosis. Leigh syndrome is a progressive neurodegenerative disorder characterized by symmetric necrotizing lesions in the brainstem and basal ganglia, presenting with developmental regression, movement abnormalities, and respiratory dysfunction. Red flags for mitochondrial disease include multi-organ involvement that cannot be explained by a single conventional diagnosis, persistent lactic acidosis, and a combination of neurological and non-neurological features such as cardiomyopathy, liver dysfunction, or sensorineural hearing loss. Inheritance may be maternal when the causative mutation is in mitochondrial DNA, or autosomal when the mutation affects nuclear-encoded mitochondrial proteins. The evaluation of a child with suspected neurodevelopmental regression follows a tiered approach that moves from broadly applicable initial investigations to more targeted testing. First-tier investigations include brain MRI, which may reveal characteristic patterns of white matter disease or basal ganglia abnormalities that narrow the differential diagnosis, along with basic metabolic screening including serum lactate and ammonia levels. Genetic testing, including whole exome sequencing and mitochondrial DNA analysis, has become increasingly important as a diagnostic tool and can often establish a definitive diagnosis. Specific enzyme assays, which can be performed on blood, fibroblasts, or other tissues, allow definitive diagnosis of many lysosomal storage diseases when a specific condition is suspected. Cerebrospinal fluid analysis for neurotransmitter metabolites and lactate provides additional diagnostic information in selected cases. Neurodevelopmental regression: red flags, metabolic causes, mitochondrial, evaluation --- ### Section 9: Neurocutaneous Syndromes Neurofibromatosis type 1 is the most common neurocutaneous syndrome and is diagnosed clinically when two or more of the following seven diagnostic criteria are present: six or more cafe-au-lait macules measuring greater than 5 millimeters in prepubertal children or greater than 15 millimeters in postpubertal individuals, two or more neurofibromas of any type or one plexiform neurofibroma, axillary or inguinal freckling, optic pathway glioma, two or more Lisch nodules on slit-lamp examination of the iris, a distinctive osseous lesion such as sphenoid wing dysplasia or long bone cortical thinning, and a first-degree relative with neurofibromatosis type 1. Complications of the disorder are diverse and include learning disabilities, which are the most common neurological complication, optic pathway gliomas that require regular ophthalmological surveillance, and scoliosis. Screening consists of annual physical examination with monitoring of growth and development, along with regular ophthalmological assessment to detect optic pathway gliomas before visual deterioration occurs. Tuberous sclerosis complex is an autosomal dominant neurocutaneous syndrome caused by mutations in the TSC1 or TSC2 genes and is characterized by the growth of benign hamartomas in multiple organ systems. The cutaneous manifestations include hypopigmented ash-leaf spots that may be the earliest visible sign, detectable in infancy under Wood's lamp illumination, the shagreen patch, which is a connective tissue nevus typically found on the lower back, and facial angiofibromas, which are reddish papules that develop in a malar distribution during childhood. Brain involvement includes cortical tubers, which are areas of disorganized cortical architecture that serve as epileptogenic foci, and subependymal giant cell astrocytomas, known as SEGAs, which are benign but can grow to obstruct cerebrospinal fluid flow and cause hydrocephalus. Seizures are extremely common in tuberous sclerosis complex, and infantile spasms are a particularly characteristic early presentation. Other organ involvement includes renal angiomyolipomas and cardiac rhabdomyomas, the latter of which may be detected prenatally on fetal echocardiography. Treatment of the tumorous manifestations of tuberous sclerosis complex has been advanced by the use of mTOR inhibitors such as everolimus, which target the dysregulated mTOR signaling pathway that drives hamartoma growth. Sturge-Weber syndrome is a sporadic neurocutaneous disorder characterized by the triad of a facial port-wine stain, a leptomeningeal angioma, and glaucoma. The port-wine stain is a capillary vascular malformation typically located in the distribution of the ophthalmic division of the trigeminal nerve, though it may extend to other facial territories. The ipsilateral leptomeningeal angioma produces progressive neurological complications including seizures, which are the most common neurological manifestation, contralateral hemiparesis, and intellectual disability resulting from chronic venous congestion and ischemia of the underlying cortex. Neuroimaging characteristically demonstrates cortical calcifications in a pattern described as "tram-track" calcifications, visible on CT as parallel gyriform lines of calcium deposition in the parieto-occipital cortex. Von Hippel-Lindau disease is an autosomal dominant tumor predisposition syndrome caused by mutations in the VHL tumor suppressor gene that result in the development of characteristic tumors in multiple organ systems. The central nervous system manifestations include hemangioblastomas, which are highly vascular benign tumors that arise most commonly in the cerebellum and spinal cord. Retinal hemangioblastomas are another hallmark feature and can cause visual impairment if not detected and treated early. Other important associated tumors include renal cell carcinoma, which is the leading cause of mortality in the syndrome, and pheochromocytoma, which requires screening due to the risk of hypertensive crises. Management is centered on regular imaging surveillance of the brain, spine, retina, abdomen, and adrenal glands to detect tumors early and intervene before complications develop. Neurocutaneous syndromes: NF1, TSC, Sturge-Weber, VHL --- ### Section 10: Pediatric Movement Disorders Sydenham chorea is the most common acquired chorea of childhood and occurs as a delayed manifestation of rheumatic fever following group A streptococcal pharyngeal infection. The clinical features include chorea, which manifests as involuntary, irregular, purposeless movements of the face, trunk, and extremities, along with emotional lability with mood swings and irritability, and generalized muscle weakness that may be mistaken for motor clumsiness. The diagnosis is supported by evidence of recent streptococcal infection, including elevated anti-streptolysin O or anti-DNase B titers, and by the presence of other features of rheumatic fever. Treatment includes penicillin prophylaxis to prevent further streptococcal infections and subsequent cardiac complications, and symptomatic treatment of chorea with valproate or tetrabenazine when the movements are functionally disabling. The prognosis is generally favorable, with chorea resolving over weeks to months in most patients, although recurrences may occur with subsequent streptococcal infections. Tic disorders and Tourette syndrome represent a spectrum of conditions characterized by involuntary, rapid, repetitive movements or vocalizations. Tourette syndrome is defined by the presence of multiple motor tics and at least one vocal tic, occurring for more than one year with onset before age 18. The onset of tics typically occurs between 4 and 6 years of age, with the peak severity of symptoms at approximately 10 to 12 years. Comorbid psychiatric conditions are extremely common in Tourette syndrome, with attention-deficit/hyperactivity disorder and obsessive-compulsive disorder being the most frequently co-occurring conditions and often causing more functional impairment than the tics themselves. Treatment options include comprehensive behavioral intervention for tics, known as CBIT, which is a first-line non-pharmacological approach, alpha-2 adrenergic agonists such as clonidine and guanfacine for mild to moderate tics, and antipsychotic medications for severe, functionally disabling tics. The prognosis is generally favorable, with many patients experiencing significant improvement or resolution of tics by adulthood. Acute dystonic reactions are a dramatic and frightening neurological emergency caused by medications that block dopamine receptors. The most common causative agents are dopamine antagonists including metoclopramide and antipsychotic medications, which can trigger an acute dystonic reaction within hours to days of initiation. The clinical presentation consists of sustained, involuntary muscle contractions producing abnormal postures, with oculogyric crisis, or sustained involuntary upward deviation of the eyes, being a characteristic and dramatic manifestation. Treatment with intravenous diphenhydramine or benztropine produces rapid and reliable relief of the dystonia. Prevention requires awareness of the risk and avoidance of causative agents when possible. The distinction between stereotypies and tics is an important clinical differentiation that arises frequently in pediatric neurology practice. Stereotypies are rhythmic, repetitive, fixed-pattern movements such as hand flapping, body rocking, or head banging, whereas tics are characteristically non-rhythmic and variable in their expression. Stereotypies are less suppressible than tics, while tics can typically be voluntarily suppressed for brief periods, though at the cost of building inner tension. Tics are preceded by a premonitory urge, a sensation of building tension that is relieved by performing the tic, whereas stereotypies lack this premonitory sensory component. The age of onset differs as well, with stereotypies typically appearing early, before 3 years of age, while tics characteristically emerge later, between 4 and 6 years. Common examples of stereotypies include hand flapping and rocking, while tics typically manifest as eye blinking, facial grimacing, or throat clearing. Pediatric movement disorders: Sydenham, Tourette, dystonic reaction, stereotypies --- ## Summary - Developmental milestones: no social smile by 3 months, no sitting by 9 months, no words by 16 months = red flags - Regression: urgent evaluation; consider metabolic, mitochondrial, neurodegenerative - Cerebral palsy: non-progressive motor disorder; spastic most common; management is supportive - Infantile spasms: clusters of spasms, hypsarrhythmia; ACTH or vigabatrin - Childhood absence epilepsy: 3 Hz spike-wave; ethosuximide; usually remits - Simple febrile seizures: no workup needed; 2-4% develop epilepsy - DMD: X-linked, proximal weakness, CK very elevated; steroids prolong ambulation - SMA: SMN1 mutation; new treatments (nusinersen, gene therapy) transforming outcomes - NF1: cafe-au-lait spots, neurofibromas, Lisch nodules; optic glioma surveillance - TSC: cortical tubers, seizures (infantile spasms), ash-leaf spots; mTOR inhibitors --- ## Key Terms | Term | Definition | |------|------------| | Global developmental delay | Significant delays in ≥2 developmental domains before age 5 | | Cerebral palsy | Non-progressive motor disorder from early brain injury | | Infantile spasms | Seizure type with clusters of flexion/extension; West syndrome | | Hypsarrhythmia | Chaotic high-amplitude EEG pattern in infantile spasms | | Febrile seizure | Seizure with fever in child 6 months-5 years without CNS infection | | Gower's sign | Using hands to "walk up" legs when rising; proximal weakness | | Neurocutaneous syndrome | Genetic disorders affecting skin and nervous system | | Regression | Loss of previously acquired developmental skills | --- *This content is subject to the [MIT License](https://opensource.org/licenses/MIT). © 2024–2026 Hibbert School of Medicine.*