Sensory & Motor Systems Lesions

Question 1

Describe effect of UMNL on muscle state

Answer 1

Minimal (disuse atrophy) due to:
Loss of voluntary & reflex muscle activity
No loss of trophic effects on metabolism of the affected muscle as nerve supply is intact

Question 2

Compare UMNL & LMNL with respect to reflexes

Answer 2

UMNL, all superficial are lost except +ve babniski, hyperreflexia in deep
LMNL, all superficial are lost, hyporeflexia in deep

Question 3

Mention distinguishing characters of acute UMNL from LMNL

Answer 3

Widespread, +ve Babniski, No atrophy

Question 4

Compare characters of corticobulbar & facial nerve lesion

Answer 4

CB: upper face is spared, lower face is affected, contralateral
FN: upper & lower face are affected, ipsilateral

Question 5

Mention acquired causes of polyneuropathy

Answer 5

1. Metabolic as DM
2. Autoimmune
3. Toxins
4. Tumors
5. Trauma
6. Nutritional def
7. Alcohol
8. Vascular

Question 6

Describe sensory & motor effects of polyneuropathy

Answer 6

S, numbness, tingling, pricking then hypothesia then anesthesia. Glove & stocking sensory loss
M, paresis, paralysis, loss of reflexes, atrophy (LMNL)

Question 7

Define syrinomyelia

Answer 7

Cyst or glial tissue or fluid that accumulates over time causing cavitation around central canal, more common in cervical segments, may progress to thoracic segments and medulla

Question 8

Describe effect of small lesion in syringomyelia

Answer 8

Damage of decussating fibers of spinothalamic tract resulting in sensory loss of pain & temp in upper limbs & upper chest & back (jacket distribution of sensory loss)
Crude touch (partially carries in dorsal column pathway) & other dorsal column senstaions are not lost.

Question 9

Describe effect of progressive lesion in syringomyelia

Answer 9

Sensory as small lesion
Motor, LMNL due to damage of AHCs at level of affected segments & UMNL below level due to damage of corticospinal tract
Autonomic: damage of LHCs, Horner’s syndrome

Question 10

Describe effect of more progressive lesion in syringomyelia

Answer 10

Sensory as progressive
Motor as progressive with addition of cranial nerve nuclei (syrigobulbia)
Autonomic as progressive
Brain stem affection with various kinds of facial palsy, sensory & motor impairments

Question 11

Tabes dorsalis more commonly affects …..segments

Answer 11

Lumbosacral

Question 12

C/P of late stage syphilis

Answer 12

Sensory loss
Sensory ataxia
Stamping gait
Motor effects (deafferenation, hypotonia & hyporeflexia)

Question 13

First & last sensation lost in tabes dorsalis, why?

Answer 13

Vibration first
Slow pain last, as the lesion causes compression from inside to outside, the pain fibers are located centrally.

Question 14

Define stamping gait

Answer 14

Lifting legs very high to hit the ground hard, with opened eyes looking at legs

Question 15

Define Argyll-Robertson pupil

Answer 15

Loss of eye pupil reaction to light while the pupil itself is normal & can respond to other reflexes such as near response reflex
Occurs in more progressive stages of Tabes dorsalis with brain stem affectiondue to damage of pretectal area of midbrain

Question 16

Describe effects of Brown-Sequard Syndrome

Answer 16

At level of lesion: LMNL & Loss of all sensations
Below level of lesion: ipsilateral UMNL, Ipsilateral loss of dorsal column sensations, contralateral loss of spinothalamic sensations.

Question 17

Causes of spinal cord transection

Answer 17

Gunshot injuries, dislocation of spine, vascular accident

Question 18

GR: Transection of spinal cord above C5 leads to death

Answer 18

Due to interruption of impulses between respiratory center and C3,4,5 (origin of phrenic nerve) leading to respiratory failure.

Question 19

In Transection of spinal cord below C5 respiration is ……while mid-thoracic it is ……

Answer 19

Diaphragmatic only
Diaphragmatic & intercostal

Question 20

Describe cause & duration of spinal shock

Answer 20

Due to sudden withdrawal of the facilitatory corticospinal, reticulospinal & vestibulospinal impulses thus dec excitability if spinal motor neurons & loss of response to stimulation of afferents
2-6 weeks depending on degree of encephalization of motor function

Question 21

Mention locomotor effects of spinal shock

Answer 21

1. Loss of stretch reflex, atonia, areflexia & fkaccid muscles
2. Loss of flexor withdrawal reflex & superficial reflexes
3. Muscle atrophy
4. Bone demineralization and hypercalcemia which is dangerous on hear & kidnney. Matrix protein degenration

Question 22

Mention autonomic effects of spinal shock

Answer 22

1. Loss of autonomic reflexes resulting in atonia in wall & sphincters of bladder & rectum
2. Loss of vasomotor control on sympathetic lateral horn cells, resulting in loss of vasomotor tone & hypotension

Question 23

Describe vascular effects of spinal shock

Answer 23

1. Blood flow to paralyzed limb is decreased while venous return is also decreased thus the limb becomes cyanosed with dec nutrition
2. Bed ulcers may occur especially in dependent areas

Question 24

Mention causes of reflex recovery

Answer 24

1. Denervation hypersensitvity of remaining neurons thus can respond to afferent stimulation
2. Increased collaterals from existing neurons & more formation of excitatory endings on interneurons & motor neurons.

Question 25

Explain mass reflex

Answer 25

Due to denervation hypersensitivity, release phenomenon from inhibitory gamma motor neurons and increased collateral in spinal cord. Large portion of spinal cord is stimulated at the same time with possibility of irradiation and reverberating circuits between these collateral neurons.

Question 26

Mention acute stage thalamic syndrome manifestations

Answer 26

1. Sensory loss of all sensations of opposite side (body & face) 2. Secondary hyperalgesia due ti release from gate inhibition 3. Sensory ataxia

Question 27

Mention delayed stage thalamic syndrome manifestations

Answer 27

1. Recovery of crude sensations but they are more crude 2. Fine sensations are never recovered 3. 2ry hyperalgesa 4. Thalamic hyperpathia 5. Emotional disturbance 6. Motor ataxia 7. Paroxysmal attacks of pain due to release from gate inhibition

Question 28

Compare sensory & motor ataxia

Answer 28

Sensory, due to loss of proprioception, finger to nose test can be done only with eyes opened, finger move behind & after nose, +ve Romberg, stamping gate. Motor, due to cerebellar lesion, finger to nose test shows hypermetria even with open eyes, -ve Romberg, zigzag like gate.

Question 29

Distribution of anterior spinal artery

Answer 29

It supplies medial part of medulla oblongata and ant 2/3 of the cross sectional area of spinal cord, which is anterior and lateral white columns, anterior & lateral horns, base of dorsal horn.

Question 30

Describe origin of posterior spinal arteries

Answer 30

From vertebral or more commonly from its posterior cerebellar branch

Question 31

Distribution of posterior spinal arteries

Answer 31

Posterior 1/3 of spinal cord, posterior white column & post horn

Question 32

Describe origin of radicukar arteries

Answer 32

Vertebral, ascending cervical, posterior intercostal & 1st lumbar

Question 33

Mention an infectious cause of LMNL

Answer 33

Poliomyelitis

Question 34

Describe effects of UMNL on reflex activity

Answer 34

-Exaggerated reflexes in opposite side -Hypertonia due to loss of supraspinal inhibition on gamma fibers, marked in antigravity muscles -Spasticity of clasp knife character due to Golgi tendon stimulation -Hyperreflexia of deep reflexes & tendon jerk, clonus occurs which rpare repeated cycles of stretch-inverse stretch reflex -Loss of superficial abdominal reflexes -Positive babniski sign

Question 35

Describe effects of UMNL on voluntary movements

Answer 35

-Generalzied contralateral hemiplegia, if the lesion is below level of medulla it will be ipsiltaeral -Imrovement of gross movements of axial & proximal muscles in 2 weeks but distal movement is lost -This is due to intact ipsillateral corticospinal fibers thatvterminate of medial alpha cells that mediate gross movement -Patiaent can walk with a gait knwon as circumduction

Question 36

Define fasciulation & fibrillation & causes

Answer 36

Fasciculation is jerky, visible contractions of group of muscle fibers it is both seen & felt. Due to pthalogic discharge of spinal motor neurons Fibrillation is irregular contraction of individual fibers invisible to eye but is felt & detected elecrhysiologically Due to denervation hypersensitivity to circulating Ach

Question 37

Describe effects of LMNL

Answer 37

1. Ipsilateral flaccid paralysis 2. Loss of muscle tone, deep reflexes & superficial reflexes of the affected muscle 3. Muscle atrophy due to loss of voluntary & reflex activity and due to & trophic effects on metabolism of affected muscle due to damage of nerve supply. 4. Fasciculations & fibrillations of affected muscle