SECRETS Neurology - Syringomyelia, Trigeminal Neuralgia, VitB12 Deficiency

Question 1

syringomyelia

Answer 1

expanded fluid-filled cavity in central canal of spinal cord

Question 2

syringomyelia sx & why

Answer 2

compress anterior white commissure = affect spinothalamic tract – loss of pain, temperature, crude touch

Question 3

syringobulbia

Answer 3

fluid-filled slit-like cavities in medulla

Question 4

syringomyelia association

Answer 4

type II chiari malformation (herniation of cerebellar tonsils into foramen magnum)

Question 5

“suspended-dissociated” loss

Answer 5

suspended = dermatomes above and below syrinx are unaffected
dissociated = only pain, temp, crude touch affected

Question 6

syringomyelia progression

Answer 6

LMN muscle atrophy, hyporeflexia if expanded to compress ventral horns

Question 7

trigeminal neuralgia sx & dx

Answer 7

dx based on hsx
sx = pain of sudden, shooting quality involving 1+ branches of CNV unilaterally, lasting sec-min
pain may be accompanied by facial spasms, tics

Question 8

CNV pathway

Answer 8

nuclei --> posterior fossa --> pons
exit cranium via
1 = superior orbital fissure
2 = foramen rotundum
3 = foramen ovale

Question 9

trigeminal neuralgia cause

Answer 9

young pt = MS

old pt = idiopathic

Question 10

CNV distribution

Answer 10

ophthalmic V1 = nose, eyes, forehead posterior to hairline
maxillary V2 = upper jaw and cheek
mandibular V3 = lower jaw NOT angle

Question 11

CNV carries what

Answer 11

ALL SENSORY INFO from face

pain, temp, fine touch, vibration, proprioception

Question 12

CNV nuclei

Answer 12

principal sensory nucleus = tactile sensation
spinal nucleus = pain/temp
mesencephalic nucleus = proprioception for chewing muscles

Question 13

trigeminal neuralgia tx

Answer 13

carbamazepine = anticonvulsant that reduces rate of nerve transmission by inhibiting voltage-gated Na+ channels in neurons

Question 14

VitB12 deficiency causes

Answer 14

malnutrition
chronic alcoholism
malabsorption

Question 15

VitB12 deficiency blood smear

Answer 15

large, immature oval RBCs

hypersegmented PMNs

Question 16

megaloblastic anemia pathophysiology

Answer 16

folate + vitB12 are necessary for DNA synthesis

if impaired by deficiency, no DNA synthesis
RNA & protein synthesis OK
expanding cytoplasmic volume but no mitosis –> large, immature RBC

Question 17

Romberg sign & assoc with VitB12 deficiency

Answer 17

can’t stand still with eyes closed
proprioceptive sensory loss

demyelination of dorsal columns
vitB12 deficiency –> buildup of propionyl CoA –> prevent normal myelination

Question 18

Babinski sign & assoc with VitB12 deficiency

Answer 18

spontaneous dorsiflexion of big toe upon plantar stimulation

UMN

demyelination of corticospinal tracts

Question 19

VitB12 dx

Answer 19

methylmalonic acid level

B12 is cofactor for methylmalonyl CoA –> succinyl CoA
B12 deficiency = buildup of methylmalonyl CoA