Neuroscience Flashcards
Intramedullary lesions
produce burning or tingling pain in extremities
May spare sensation in perineal and sacral areas (located on periphery of cord)
Intradural lesions
Commonly benign masses (schwannomas of spinal
Usually painless, present w/ gradual symptoms
Extradural lesions
Tend to be more malignant processes (infections or cancer)
Associated w/ severe pain- bone destruction
Symptoms can progress rapidly
Cauda Equina Compression
Signs and Symptoms
□ Numbness in genitals, buttocks, and anus due to compression of sacral nerve roots (Saddle anesthesia)
□ Lower extremity weakness, often asymmetrical
□ Decreased knee reflexes
□ Bowel and bladder retention (often a later finding)
□ Pain if a disc herniation is the case
Cause of Cauda Equina Compression
herniated disk at L4,L5 or L5-S1
Conus medullaris Compression
Signs and Symptoms
□ Knee reflexes preserved, ankle reflexes gone
□ Bowel/bladder incontinence develop early, as does impotence
Lhermitte’s Sign
electrical sensation
® Runs down back into limbs
® Caused by neck flexion
® Most commonly occurs in MS
Posterior cord syndrome
□ Loss of proprioception due to involvement of dorsal columns:
® Underrated syndrome
® Abnormal sensations, parethesias- burning, tingling, buzzing
® Can make patients miserable
® Central pain- originates in CNS
Anterior cord syndrome
□ Motor deficits- below lesion (corticospinal)
□ Loss of pain and temperature sensation (spinothalamic)
® Proprioception intact- sparing of dorsal columns
□ Bowel and bladder dysfunction, impairment of sexual function
□ Occlusion of anterior spinal artery (most common)
® Supplies anterior 2/3 of cord
Central cord syndrome
□ Loss of pain and temperature in arms, hands, and around shoulders and torso (shawl distribution)
® - disruption of spinothalamic tract as it crosses
® Lower extremities can be affected, not to same extent
□ Weakness of arms and hands- involvement of anterior horn cells w/in gray metter
Hemicord syndrome
□ Weakness on same side of lesion- injury of corticospinal tract (ipslateral)
□ Loss of proprioception on same side- injury to dorsal columns (ipslateral)
□ Loss of pain and temperature sensation on opposite side of lesion- injury to spinothalamic tract (contralateral)
□ Stabbed in the back
Transverse lesions
□ Complete motor or weakness loss below the lesions
® Paraparesis- weakness of the legs
® Quadraparesis- weakness of the arms and legs
® Paraplegia- paralysis of the legs
® Quadraplegia- paralysis of the arms and legs
□ Loss of sensation- damage to spinothalamic tract and dorsal columns
□ Bowel and bladder dysfunction, impairment of sexual function
□ i.e. transverse myelitis
Spinothalamic tract
pain and temperature from the opposite side of the body
ascending
Upper motor neuron signs
® Weakness, increased tone/spasticity, increased reflexes
® Pathological reflexes (Babinski, Hoffman’s signs)
® Lack of atrophy
Clonus
Continuous involuntary muscle contraction, relaxation
Lower motor neuron signs
® Damage to anterior horn cells or peripheral nerves
® Decreased tone, decreased reflexes, atrophy, fasciculations
® Flaccid, atrophy…
Corticospinal tract
motor to same side of the body
descending
Dorsal columns/Medial Lemniscus tract
proprioception and vibration from same side of body
ascending
Adrenoleukodystrophy
Disorder of peroxisomal function
By gross pathology: disorder of adrenal and white matter
By EM: disorder of peroxisomal storage
Biochem: disorder of deficient activity of VLCFA
Eufibers, deep white matter completely gone
Enlarged cortical adrenal cells w/ prominent striations
Krabbe’s disease
□ Autosomal recessive
□ Deficiecny of enzyme galactosyl ceramidase
□ Chromosome 14q31
□ Globoid cells w/ galactocerebroside shunting of galactocerebroside to phychosine
□ Very destructive, kills brain cells
□ Deteriorating around 4/5 months
□ Dense gliosis of the brain
□ Globoid cells- macrophages accumulating substance that isn’t being properly digested
Differential Diagnoses for Leukodystrophy
□ Infantile Krabbe Disease- begins w/in first year of life
□ Metachromatic LD: 2nd year of life
□ Spongy degeneration: megalencephaly
□ Pelizaeus- Merzbacher: abnormal eye movements, microcephaly
□ Neonatal adrenoleukodystrophy- affects brain, liver, retina
Leukodystrophy
§ Hereditary
§ Normal early development
§ Affect brain myelin and causes regression
§ Commonly fatal
§ Progressive
□ Cognitive deterioration
□ Neuropsychiatric difficulties
□ Pyramidal and cerebellar abnormalities
□ Visual abnormalities
□ Deafness
§ Dementia and death within a few yearsGaucher disease
Lysosomal storage disorder
§ Autosomal recessive
§ Most prevalent lysosomal storage disease
§ Deficiency of enzyme, accumulation of glucocerebroside
§ Rare cases- deficiency of…
§ Non-neruonopathic form
□ Adult onset (Type 1)- hepatosplenomegaly, pancytopenia, skin
□ Bond- deformities of distal femur (Erlenmeyer)
§ Neuronopathic forms
□ Infantile (Type II)- rapidly progressive
□ Juvenile (Type III)- slowly progressive
Disorders of gray matter
§ Alpers-Huttenlocher syndrome
§ Pantothenate-kinase associated neurodegeneration
§ Menke’s disease
§ Leigh’s disease
Disorders of white matter
leukodystrophes
Metabolic diseases
associated with genetic defects involving specific cellular organelles: lysosomes, peroxisomes, mitochondria
unable to handle metabolism of neurons to execute their function, defect in myelination
Germinal matrix hemorrhage
○ Precise factors are unknown
○ Prematurity is commonest association
○ Not necessarily associated w/ stressed-out fetus
○ Hemorrhage may be localized or spread into ventricles and beyond
§ Can expand ventricle or explode into germinal matrix back into the brain (Grade IV)
○ Lower incidence when mom’s were given K+ early on in fetal distress
Stabilizes germinal matrix
Dandy-walker malformation
§ Triad of 4th ventricle cystic dilatation, vermal agenesis, and enlargement of posterior fossa
□ Vermis between R and L cerebellar hemispheres
□ Cyst expands, full of fluid
§ Patency of foramina of Lushka and Magendie variable
□ Closed- fluid obstruction, hydrocephalus
§ Aplasia of the entire cerebellar vermis in 1/4 of patients
□ Can almost always find small remnants microscopically
Arnold-chiari malformation (Chiari Type II)
§ Small posterior fossa with downward displacement of cerebellar tissue (vermis) through foramen magnum
□ Malformation of skull?
§ Caudal displacement of medulla
§ Associated with hydrocephalus and lumbar meningomyelocele
§ Pathogenesis uncertain
§ Hydrocephalus
Hydranencephaly
§ Cerebral hemispheres largely absent
§ Fluid filled cavity instead
§ Fetal hypoxia, maternal intoxication, twinning
§ Skull present, often externally normal
Secondary destruction - brain tissue killed by hypoxic ischemic insults
Agenesis of corpus callosum
§ Brain won’t learn how L and R talk to each other
§ Absence of white matter bundle connecting both hemispheres
§ Sporadic or inherited
§ Associated conditions: holoprosencephaly, midline tumors (lipoma, meningioma, etc.)
Microcephaly (micrencephaly)
§ Small brain § Numerous genetic syndromes, alcohol, drugs, viruses § In late stage of development § Very non-specific § Look at the family** small/large head?
Double cortex
§ Neurons made it half-way
§ Mutations in double cortin
§ Not connected appropriately, can be a cause of seizures
Nodular ventricular heterotopia
§ Nodular and laminar heterotopia
§ Neurons mature in wrong spot
§ Normal looking neurons, but not connected to anything else
Polymicrogyria
§ Small, irregularly formed, numerous individually thin gyri
§ Cobblestone appearance
§ Loss of external contours of the convolutions of the brain
§ Many genetic syndromes associated
§ Twinning, VZV, CMV, Toxo, syphillis….
Pachygyria (macrogyria)
§ Reduced number of broadened convolutions (gyri)
§ Reduction in number of neurons reaching neocortex
§ Results in simplification of gyral foldings
Agyria (lissencephaly)
§ Small brain with smooth cerebral surface
§ Absence of gyri and sulci
§ Neuroblasts migrated into subarachnoid space
Defect in border preventing neurons from getting out
Arrhinencephaly
olfactory aplasia
Agenesis of olfactory bulbs and tracts and related structures
Mildest form of craniofacial anomalies
Incidental, or with holoprosencephaly
