SECRETS Neurology - Basics & ALS

Question 1

+ strength of muscle contraction

Answer 1

recruitment of additional muscle units

Question 2

LMN lesions

Answer 2

flaccid paralysis
weakened reflexes
fasciculations
muscle atrophy

Question 3

UMN lesions

Answer 3

spastic paralysis
heightened reflexes
positive Babinski sign

Question 4

cerebellar lesions = contra or ipsi? why?

Answer 4

IPSI

send projections to contra motor cortices & red nucleus that send projections to contra motor neurons

cerebellum –> contra cortex/nucleus –> contra motor neurons = IPSI symptoms

Question 5

spinothalamic tract sensations

Answer 5

pain
temperature
light touch
pressure

Question 6

dorsal column sensations

Answer 6

fine touch
vibration
pressure
proprioception

Question 7

fasciculus gracilis

Answer 7

lower extremities
lower thorax

below T7

medial

Question 8

fasciculus cuneatus

Answer 8

upper extremities
upper thorax

C2-T6

lateral

Question 9

corticospinal tract crossover

Answer 9

inferior medulla

via medullary pyramids

Question 10

dorsal column crossover

Answer 10

caudal medulla
via internal arcuate fibers

between nuclei in brainstem & thalamus

Question 11

spinothalamic tract crossover

Answer 11

spinal cord - anterior white commissure

Question 12

dorsal horn

Answer 12

sensory

Question 13

ventral horn

Answer 13

motor

Question 14

brown-sequard syndrome

Answer 14

lateral hemisection of spinal cord

Question 15

brown-sequard syndrome

motor neuron sx

Answer 15

ipsi LMN & UMN

Question 16

brown-sequard syndrome

sensory sx

Answer 16

ipsi dorsal column = fine touch, vibration, proprioception

contra spinothalamic = pain/temp

Question 17

lesion of internal capsule sx

Answer 17

contra hemiplegia
contra sensory loss

ALL PATHWAYS = contra sx

Question 18

type I vs type II muscle fibers

Answer 18

I = slow twitch
II = fast twitch

Question 19

type grouping

Answer 19

normal histology = type I & II muscle fibers intermingled like a checkerboard

when muscle fibers lose innervation (death of anterior horn cell), neighboring muscle fibers sprout new axons and take over –> type grouping

muscle fibers of same type are grouped together with loss of checkerboard pattern

Question 20

ALS sx

Answer 20

UMN
LMN

muscle weakness, disability, death
hyperreflexia, spastic paralysis, clonus

NO sensory or cognitive dysfunction

spare extraocular muscles

Question 21

ALS pathology

Answer 21

loss of pyramidal cells in motor cortex –> fibrosis & astrocytic gliosis of lateral corticospinal tracts

loss of ventral horn neurons –> thin ventral nerve roots

Question 22

ALS development

Answer 22

acquired

familial = zinc/copper superoxide dismutase 1 gene mutations

Question 23

syringomyelia vs. ALS

Answer 23

both initially present with atrophy of intrinsic hand muscles

sphingomyelia also affects decussating fibers in spinothalamic tract = bilateral loss of pain/temp in UE