Sensory dysfunction disorders

Question 1

what happened to ian waterman

Answer 1

severe bout of gastric flu
body produced antibodies that attacked and killed his nerves via demyelination
(large fibre neuropathy)

Question 2

what has IW lost and kept due to large fibre neuropathy

Answer 2

kept pain and temp sense (small fibres)
kept MNs (intact)
permanently lost all touch sensation and proprioception below the neck

Question 3

how does IW live with large fibre neuropathy

Answer 3

compensates for loss of proprioception by relying on visual, vestibular, and auditory cues
(shows importance of somatosensory feedback in motor control)

Question 4

what are the 2 types of diabetes

Answer 4

type 1 = insulin not produced by pancreas
type 2 = no longer effective at breaking down sugars (desensitised)

Question 5

what is DPN (diabetic peripheral neuropathy)

Answer 5

toxic levels of glucose in the bloodstream causes DPN
hyperglycemia mainly affects the nerves
affects afferent fibres carrying pain and temp info / touch/proprioceptive info (also affects muscles)

Question 6

what are the symptoms of DPN

Answer 6

pain and burning sensation in the distal extremities
loss of important somatosensory feedback for balance control and dextrous use of hands

Question 7

what is glove and stocking hypoesthesia

Answer 7

numbness
- starts distal and moves proximal

Question 8

what is distal hyporeflexia

Answer 8

weakness
- feet first, then hands

Question 9

what is the difference in amplitude of response and timing in DPN during nerve conduction tests

Answer 9

ampltiude = significantly decreased
latency = same because nerve conduction doesn’t change
(increase in latency in reflex tests is due to somatosensory deficits not conduction speed)

Question 10

what is vibration white finger syndrome

Answer 10

peripheral neuropathy that occurs thorugh exposure to high levels of vibration for extended periods of time

Question 11

what does VWFS affect

Answer 11

blood vessels, nerves, muscles, and joints of the hand, wrist and arm

Question 12

at what frequencies does injury occur (VWFS)

Answer 12

between 5-2000 Hz
greatest risk of fingers = 50-300 Hz (pacinian corpuscles)

Question 13

what is carpal tunnel syndrome

Answer 13

occurs as a result of nerve entrapment from repetitive, overuse injury at the wrist (ex: computer work)
- bones of the carpal tunnel begin to compress and damage the peripheral nerves (median nerve commonly)

Question 14

what is the prevalence of carpal tunnel syndrome

Answer 14

affects 5-7% of general population
most common disorder assessed by neurological exam

Question 15

what are the assessments for CTS

Answer 15

nerve conduction studies
- gold standard
- positive test = conduction velocity is delayed (<40ms)
phalen test
- quick - wrists held together flexed for 1 minute
- postiive test = tingling in fingers, thumb, or palm

Question 16

is CTS due to nerve inflammation

Answer 16

no
- inflammation from tendons and bursa sacs reduces the space for the nerve in the carpal tunnel

Question 17

what is the treatment for CTS

Answer 17

attempt to release the nerve
- bracing, steroid injections, or nerve release surgery
- peripheral nerve will recover once released as long as there isn’t significant damage

Question 18

what is blindsight

Answer 18

individuals with cortical blindess can actually detect the presence of targets and determine line orientation within their scotoma
(scotoma = region with no perception of visual info)

Question 19

what does blindsight show about the visual streams

Answer 19

shows that visual info for action is different from visual info for perception (dorsal vs ventral)
believed that blindsight relies on visual info arriving in the dorsal stream without going through V1 (lesion)
(can use dorsal stream even when there are lesions in V1

Question 20

what is vertigo

Answer 20

person feeling as though they or the objects around them are moving even when they are not

Question 21

what are the 3 main causes of vertigo

Answer 21

misplaced otoconia
menieres disease
labyrinthitis

Question 22

what is the the effect in BPPV (benign paraoxysmal positional vertigo) due to misplaced otoconia

Answer 22

otoconia become dislodged and float in the vestibular labyrinth (supposed to be in otolith organs not SC canals) and bump into hair cell receptors
- give info about mvmt that isn’t correct

Question 23

what is the epley maneuver

Answer 23

series of head mvmts performed by trained physician that end up returning the otoconia to the original position

Question 24

what is menieres disease

Answer 24

results from increased pressure / volume and ionic concentration imbalance (increased K+) in the endolymph
- underlying cause unknown
- due to imbalance in the production / absorption rates of the endolymph fluid

Question 25

what is caused by the increased endolymph pressure

Answer 25

leads to swelling to the ducts and pressure upon hair cell receptors (initially irritating and eventually killing them)
- can cause hearing loss, vertigo, and tinnitus

Question 26

what is the treatment for menieres disease

Answer 26

• diuretics (remove fluid)
• diet (salt restriction)
• vestibular suppressant drugs
• extreme cases = hormones to reduce swelling and increase circulation
• last resort = gentamicin (chemical that destroys hair cells) is injected to eliminate all vestibular / auditory sensations

Question 27

what are possible other causes of vertigo

Answer 27

stroke, brain tumours, MS, migraines, trauma, uneven pressures between the middle ears (less common)