Neurology 2 Flashcards
Overview/presentation of acute cerebellar ataxia
Most common cause of ataxia, usually post infection
Ataxia develops over hours to days after illness
- nystagmus, slurred speech, difficulty with fine motor movements, truncal titration, gait instability
Should NOT have altered mental status, seizures or meningismus
Investigation/management of acute cerebellar ataxia
Clinical diagnosis, can send toxicology screen to exclude ingestions
LP if atypical features, consider neuroimaging
Treatment is supportive, usually completely resolves within 2-3 weeks
Defect in ATM gene?
Ataxia telangiectasia
- AR disorder
- ATM gene involved in DNA repair
Presentation of ataxia telangiectasia?
Normal as infants
By age 2-3 develops ataxia, progresses to wheelchair bound by 15 years
Oculomotor apraxia: cannot make fast eye movements therefore turns head
Other features - telangiectasias, immunodeficiency (low Ig and T cell dysfunction), malignancy, pulmonary disease)
Investigations and treatment of ataxia telangiectasia
Serum AFP elevated
Serum IgA low
Genetic testing for ATM gene
Treatment is supportive, median age of death in mid-20s
Overview of Friedreich ataxia
Most common hereditary ataxia, AR or sporadic
Loss of function mutations in frataxin gene, usually due to expansion of a GAA-trinucleotide repeat
Causes atrophy of spinal cord and medulla
Clinical presentation of Friedreich ataxia
Presents in adolescence with progressive ataxia
Dysarthria
Sensory loss - particularly vibration and proprioception (posterior columns, dorsal root and peripheral nerves affected)
Eventual loss of DTRs
Systemic - hypertrophic cardiomyopathy, kyphoscoliosis, DM
Investigation and management of Friedreich ataxia
Neuroimaging of brain and spinal cord to exclude other causes, genetic testing
Treatment is supportive
Usually confined to wheelchair by late teens, age of death is usually mid-30s (cardiac complications)
Spina bifida occulta overview
Spinal cord dysraphisms
Failure of spinous processes to completely form or fuse
Spinal canal and overlying skin intact, may have tuft of hair or dimple
Very common (10% of population)
Usually no neurological consequence
All other types of dysraphisms have elevated AFP on screening
Protrusion of meninges through a spinal defect?
= meningocele
- looks like a cyst over (typically) lumbar spine
- spinal cord usually remains intact
- most patients asymptomatic neurologically
Protrusion of meninges and spinal roots through defect?
= myelomeningocele
- results in severe neurological complications with variable loss of function below the spinal level of the defect
- strength and sensation usually more affected than urinary and sexual function (although all are typically involved)
Protrusion of meninges and spinal roots through defect with an open lesion over the back?
= myeloschisis
- most severe form of spinal cord dysraphism
- direct communication between spinal canal and external environment
- high risk of CNS infection
Complications of myelomeningocele and myeloschisis?
Chiari II malformations
Cognitive issues (agenesis of corpus callous, ADHD)
Latex allergy (up to 70%)
Tethered cord (subacute gait abnormalities and urinary changes, usually during periods of growth)
Encephalocele
= defect of skull closure
May be bone only defect, or may have herniation of brain contents
Most frequently anterior or posterior
Anencephaly
= failure of the brain, skull and scalp formation
Majority result in spontaneous abortion or die during bith
No treatment available
Focal cortical dysplasia
Malformation of cortical development: isolated region(s) where neurons fail to segregate appropriately into six layers
Usually frontal, but can be anywhere
MRI: loss of grey-white differentiation, a “tail” of T2 hyper intensity from cortex to lateral ventricle
Typically presents with epilepsy, usually refractory to medical therapy (may need surgery)
More numerous/smaller gyri, resulting in a “cobblestone” appearance of the cortex
= polymicrogyria
May be focal or more diverse, can be congenital or due to prenatal CNS infection’Variable severity: mild neurologic deficits to severe ID, CP, epilepsy
Treatments target symptoms
“Double cortex”
= subcortical band heterotopia - some neurons appropriately migrate to cortex, others fail, resulting in two layers of neurons on imaging often with malformed cortex
More common in girls
Presents almost always with severe neurologic impairment
“Smooth brain”
= lissencephaly
- failure to form typical gyri and sulk
- may be primarily frontal, occipital or diffuse
- presents nearly always with severe neurologic impairment
Agenesis of the corpus callosum
Disorder of midline structure formation
Varies from dysgenesis (corpus callosum present but abnormal), to partial agenesis (missing either anterior or posterior portion only) to complete agenesis
Many causes, presentations vary
May have normal IQ with subtle cognitive impairments
Septo-optic dysplasia
Disorder of midline structure formation
Triad of absence of septum pellucidum, optic nerve hypoplasia and pituitary dysfunction
Can have normal cognition (but about 50% have mild to moderate ID)
Presentation of septo-optic dysplasia
Variable presentation
Can be discovered during neonatal period (poor transition, hypotonia), infancy (delayed visual milestones, congenital nystagmus, CP) or later (endocrine dysfunction, especially growth hormone deficiency)
Needs screening of pituitary function if imaging is concerning for optic nerve and corpus callosum development
Holoprosencephaly
Most severe form is lobar, includes single eye (cyclopean) and absent/misplaced nose (proboscis)
Semilobar = partial fusion of hemispheres
Lobar = partial interdigitation of hemispheres (usually frontally)
Severity is variable depending on extent of fusion but generally severe ID, CP and epilepsy
Disorders of posterior fossa formation
Dandy-Walker malformation
Joubert syndrome
Pontocerebellar hypoplasia
Dandy-Walker malformation
Enlarged fourth ventricle, elevated torculum, agenesis of cerebellar vermis, and typically agenesis of much of the cerebellar hemispheres
- usually have midbrain and pons malformation and hydrocephalus
- have fine motor and gait impairment with variable ID
“Molar tooth” appearance of midbrain on MRI?
Joubert syndrome
- disorder of posterior fossa formation
- severe developmental outcome with variable cranial nerve and bulbar symptoms
Pontocerebellar hypoplasia
Underdevelopment of brainstem and cerebellum
Multiple genetic causes
Universally poor neurological outcomes
Chiari malformation type I
Herniation of cerebellar tonsils through foramen magnum >5mm
- apparent obstruction of flow of CSF
- congenital or acquired
- acquired usually due to trauma or connective tissue disorders
- symptoms usually due to obstruction of CSF flow/impingement of posterior fossa structures
Symptoms of Chiari malformation type I
Symptoms usually due to obstruction of CSF flow/impingement of posterior fossa structures
- headaches are WORSE with Valsalva
- dysarthria, difficulty swallowing, ataxia
- majority are likely asymptomatic
Enlargement of central canal of spinal cord?
= Syringomyelia
- causes sensory loss and weakness in bilateral upper extremities and shoulder in a “cape like” distribution
- scoliosis, tethered cord
Chiari malformation type II
Associated with myelomeningocele
Associated with hydrocephalus and cognitive impairment (c/w type I)
Radiographically unique c/w type 1: fourth ventricle herniates through foramen magnum, “beaked” tectum, “kinked” medulla
Chiari malformation type III
Most rare form of Chiari malformation
Resembles type II on imaging
Associated with occipital encephalocele or cervical spinal dysraphism
Moyamoya disease
Narrowing of the distal internal carotid artery or MCA with the appearance of compensatory collateral vessels (“puff of smoke” on imaging)
RF: sickle cell disease, NF1, T21, history of radiation
