Neuromuscular III (Spinal cord and motor neurons) Flashcards
Mechanism of action of riluzole in ALS
Likely inhibits glutamate excitotoxicity via multiple mechanisms (reduce glutamate release, block Na channels, inhibit NMDAR)
UMN variant of motor neuron disease
LMN variant
UMN: Primary lateral sclerosis (PLS)
LMN: Progressive muscular atrophy (PMA) (Also flail arm, flail leg, and genetic MND
Cause of tropical spastic paraparesis
HTLV-1 infection
Most common cause of spastic paraparesis in an AIDS patient
HIV-related vacuolar myelopathy
Most common genetic cause of hereditary spastic paraplegia
SPAST gene for spastin protein, AD inheritance
(Many other causes, including atlastin, araplegin, spartin, and maspardin)
Area of spinal cord most susceptible to watershed infarct
Upper-mid thoracic (T4-T8) - watershed territory between vertebral and aortic circulation
Part of spinal cord supplied by artery of Adamkiewicz
Lower thoracic to upper lumbar
Most common cause of familial ALS
Copper/zinc superoxide dismutase (SOD1) mutations (about 20% of familial ALS)
What supplement can cause copper deficiency myelopathy
High-dose zinc supplementation (can lead to copper deficiency)
(High dose zinc induces intestinal metallothionein production, which reduces absorption of copper, zinc, and other heavy metals)
Zoonotic illness that can lead to polio-like flaccic paralysis, as well as meningitis, encephalitis, and other manifestations
WNV (a flavivirus)
Progressive spastic paraparesis, sensory neuropathy, and adrenal insufficiency
Genetic cause?
Adrenomyeloneuropathy (AMN), a form of X-linked adrenoleukodystrophy (ALD)
X-linked, mutation in ABCD1 gene leading to VLCA accumulation
(Other forms of ALD include childhood cerebral ALD, adult cerebral ALD, and addison’s-only ALD)
Most common intradural, extramedullary spinal cord tumor
Meningioma (others include nerve sheath tumors - schwannomas and neurofibromas)
Most common intermedullary spinal cord tumors in children and adults
Children: Astrocytomas (usually low-grade)
Adults: Ependymomas
Tumor that arises from ependymal cells in the flilum terminale
Myxopapillary ependymoma
Superficial siderosis:
Common presentation?
Cause?
LP and MRI findings?
Gait ataxia and SNHL, can also have anosmia, cognitive decline, and myelopathy.
Due to recurrent bleeding into the subarachnoid space (source variable and often not identified)
LP: often xanthochromia and/or RBCs
MRI: T2 hypointensity around brain, brainstem, and spinal cord
Trace element deficiency that can mimic B12 deficiency myelopaty
Copper deficiency (can also lead to peripheral neuropathy, optic neuropathy, and CNS manifestations)
Syndrome of progressive weakness, proximal-> distal+bulbar a/w LMN signs and gynecomastia, presenting in 30s.
Genetic cause
X-linked spinpbulba musculr atrophy a.k.a. Kennedy’s disease
Trinucleotide CAG repeat in androgen receptor gene on X-chromosome
How do SMAs 1-4 vary in age of onset and severity
The higher the number, the later onset and less severe
SMA1: infantile SMA, death by 2 years
SMA2: intermediate SMA, onset 1-2 years, usually contractures and non-ambulatory
SMA3: juvenile SMA, onset 5-15 years, difficulty walking but ambulatory into adulthood
SMA4: adult-onset SMA, onset 20s-30s, usually ambulatory into late adulthood
Muscle biopsy finding in SMA
Atrophy of whole fascicles or groups of fascicles with neighboring normal or hypertrophied fascicles
Progressive asymmetric wasting of one or less commonly both hands and forearms with atrophy and fasciculations and preserved sensation, and then stabilization
Monomelic amyotrophy a.k.a. Hirayama disease
