Neuro shelf - spinal cord

contains alpha motor neurons and motor fibers innervating skeletal muscles

descends from the cortex and crosses midline in the medulla, then synapses on alpha motor neurons in anterior horm. Runs laterally in cord.

ipsilateral to origin, then crosses in brainstem

begins in peripheral nerves (pain and temp), enters cord and synapses within 2 levels, then crosses and ascends contralaterally

C1

L1-L2

respiratory insufficiency

above T6

weakness and hyperreflexia ipsilateral to and below the lesion (corticospinal tract), impaired position sense below the lesion, loss of pain and temp perception below level of lesion but contralateral to lesion

affects spinothalamic tract fibers crossing at level of lesion

deficits in pain and temp sensation bilaterally over several segments (cape-like). pain and temp affected byt NOT touch or position

ex: syringomyelia - expansion of potential fluid space in center of spinal cord. May be associated with posterior skull and brain malformations such as Chiari malformations

posterior columns (tabes dorsalis). B12 targets posterior columns also

wasing, weakness, and fasciculations in appropriately innervated muscles lumbrosacral region with pain. Sacral root dysfunction can cause bowel, bladder, and sexual dysfunction

upper motor neuron findings, radicular pain, bowel, bladder, and sexual dusfunction. If lesions are below the lumbar cord, may leave leg strength and reflexes intact while severely affecting bowel, bladder, and sexual function

anterior spinal artery

artery of adamkiewicz, entering the spinal cnal around L2

plexus fed by segmental arteries from the aorta

weakness below lesion, intense radicular pain, sphincter dysfunction, sensory loss but not position loss, thoracic cord is lease well perfused and most vulnerable. Systemic hypotension can lead ot watershed infarct affecting this area.

high doses of steroids

due to mutation in the superoxide dismutase enzyme, leading to exitotoxin damage

involve alpha motor neurons (lower motor) of anterior horm of spinal cord, leading weakness, faciculations, and wasting. Also involves lateral corticospinal tracts leading to weakness, spasticity, hyperreflexia, and Babinski signs

No sensory deficits, eye movements unaffected.

Tx: riluzole slows deterioration.

Things that mimic ALS: stenosis of spinal canal (EMG testing), hereditary spastic paraparesis (HTLV-1 testing), severe nutritional deficiency.

Things that affect alpha motor neurons but w/o spasticity or sensory deficits - spinal muscular atrophies

SMA presenting in infancy - atrophy of anterior horn cells

downward protursion of the medulla, with or without cerebellum, through the foramen magnum

hypertrophy of the filum terminale - pain and dysfunction of cord, especially at lower levels