Section 7 - Spinal Cord

Question 1

What is amyotrophic lateral sclerosis?

Answer 1

Lou Gehrig Disease. Abnormal reflexes (upper and lower motor neuron involvement). No sensory loss; progressive loss of all motor neurons. Particularly severe when muscles of respiration are affected.

Question 2

What is myasthenia gravis?

Answer 2

Autoimmune abnormality where antibodies bind to the nicotinic acetylcholine receptors at neuromusclar jxn, blocking normal effects of acetylcholine to depolarize muscle and elicit response.

Question 3

List symptoms of myasthenia gravis.

Answer 3

• Muscle weakness/compromise of ability to elicit skeletal muscle response - this waxes and wanes over time
• Diplopia, ptosis (both seen first; eye mm. affected first)
• Dysarthria (difficult/unclear speech)
• Dysphagia

Question 4

What is syringomyelia?

Answer 4

Cavitation of central region of spinal cord. NOT the central canal.

Question 5

A small syrinx damages:

Answer 5

Fibers crossing anterior white commissure (ALS); damage ALS tract destined bilaterally to specific spinal levels. (2 levels below, bilaterally).

Question 6

A large syrinx damages:

Answer 6

Anterior white commissure AND anterior horn –> bilateral sensory loss at specific levels, weakness of extremity

Question 7

What is a hydrosyringomyelia?

Answer 7

A cavitation of the central canal.

Question 8

Non-communicating syringomyelia ______.

Communicating syringomyelia ______.

Answer 8

• Is separate from the central canal.

- Has a cystic structure connecting to the central canal.

Question 9

What is Brown-Sequard Syndrome?

Answer 9

A hemisection of the spinal cord that reflects damage to lateral corticospinal tract, ALS, and dorsal columns.

Question 10

List symptoms of Brown-Sequard Syndrome.

Answer 10

• Muscle weakness/paralysis ipsilaterally
• Loss of pain and thermal sensation contralaterally
• Loss of proprioception, vibratory, fine touch ipsilaterally

Question 11

What is a radiculopathy?

Answer 11

Damage to nerve root, typical of disk/spine disease and impingement syndromes. Sharp, localized pain related to dermatome. (Single root might not cause big sensory loss, due to overlap of dermatomes).

Question 12

What is a mononeuropathy?

Answer 12

Damage to defined peripheral nerve, often from trauma or entrapment (like carpal tunnel). Leads to paresthesia, pain, weakness in target tissue.

Question 13

List some characteristic examples of a mononeuropathy.

Answer 13

• Tongue deviation (XII)
• Flexion/adduction, extension of fingers (ulnar)
• Foot dorsiflexion (fibular)
• Forearm pronation (median)
• Flexion of toes (tibial)

Question 14

What is a polyneuropathy?

Answer 14

Damage in multiple peripheral nerves, so both motor and sensory.

Question 15

What is glove and stocking sensory loss?

Answer 15

Lesions/neuropathy starts in lower extremity then begins in upper; moves from periphery to central locations (involving small diameter fibers first). Diabetes mellitus causes this.
- Lose sensation of temp/pain, then vibration/proprioception, weakness of extremities/hyporeflexia

Question 16

What is a motor neuropathy, and what does it lead to?

Answer 16

• Loss of anterior horn motor neurons

- Flaccid weakness, muscle fasciculations, muscle atrophy

Question 17

What is a sensory neuropathy, and what does it lead to?

Answer 17

• Loss of cell bodies in DRG

- Distal and proximal extremity affected

Question 18

What is a lower-motor lesion?

Answer 18

• Skeletal mm. activity affected (the final common pathway)

- FLACCID paralysis, muscle ATROPHY, diminished or ABSENT deep tendon reflexes

Question 19

What is an upper-motor lesion?

Answer 19

• Damage to cerebral hemispheres or lateral white columns of spinal cord
• SPASTIC paralysis, NO atrophy, HYPERACTIVE deep tendon reflex, Babinski’s sign
• Often caused by stroke, tumor, infection

Question 20

What results from occlusion/spasm of anterior spinal artery (Central Cervical Cord Syndrome)?

Answer 20

• Bilateral weakness of extremities (mostly upper)
• Patchy loss of sensation below lesion
• Urinary retention

Question 21

What is poliomyelitis?

Answer 21

Viral infection leading to spinal cord inflammation of gray matter

Question 22

What are symptoms of poliomyelitis?

Answer 22

• Headaches
• Red/sore throat
• Slight fever
• Vomiting
• Abnormal reflexes
• Back/neck stiffness

Question 23

What is tabes dorsalis?

Answer 23

Slow degeneration of sensory neurons in dorsal columns of spinal cord. Occurs as secondary demyelination due to untreated syphilis.

Question 24

What are symptoms of tabes dorsalis?

Answer 24

• Weakness
• Diminished reflexes
• Paresthesias
• Hypoesthesias
• Progressive locomotor ataxia

Question 25

What is spinal shock?

Answer 25

Loss of sensation accompanied by motor paralysis with gradual recovery of caudal reflexes following a spinal cord injury

Question 26

What is deafferentiation pain?

Answer 26

Nerve rootlets/tracts/nerves damaged/disrupted (lesions, damage to posterior rootlets, amputation). Results in: - Dull, aching, searing, pins-and-needles, burning sensations - Pain distributed to appropriate dermatome/region

Question 27

How do we treat deafferentiation pain?

Answer 27

DREZ (dorsal root entry zone) procedure - radiofrequency lesions made at levels of avulsed or lesion roots

Question 28

What are possible consequences of DREZ?

Answer 28

- Can damage corticospinal tract and/or cuneate tract - Weakness of extremity on same side - No proprioception, vibration on ipsilateral side (buzzing)

Question 29

What is neuropathic pain?

Answer 29

Results from damage/disease affecting somatosensory system, continuous or episodic - pain is produced by non-painful stimuli (allodynia) and associated with abnormal sensations (dysesthesia).

Question 30

Describe Acute Central Cervical Spinal Cord Syndrome (or Central cord syndrome).

Answer 30

Incomplete spinal cord injury from traumatic hyperextension of cervical spine or mechanical injury --> bilateral damage to cervical spinal cord (anterior spinal artery)

Question 31

Signs of central cord syndrome?

Answer 31

- Bilateral weakness of extremities (upper) - Patchy loss of sensation (pain, thermal) below lesion - Urinary retention Recovery is 4-6 days in reverse order of spinal cord location (bottom, up)

Question 32

What is the deep tendon reflex?

Answer 32

Stimulus of stretch (from a muscle spindle) typically elicited by tapping the large tendon - exerts rapid contraction of a muscle to resist the stretching (monosynaptic stretch reflex)

Question 33

What is the inverse myotatic reflex?

Answer 33

Autogenic/reciprocal inhibition - One group of muscles is excited and the antagonistic group is inhibited

Question 34

What is the Golgi tendon organ?

Answer 34

Responsible for autogenic inhibition; requires greater strength of stimulus (a higher muscle tension) for action than the muscle stretch (myotatic) reflex

Question 35

What is the flexor reflex?

Answer 35

Initiated by cutaneous input (nociceptive stimuli); responds to attempt to protect the body

Question 36

What is the crossed extension reflex?

Answer 36

Builds on circuit of flexor reflex; involves contralateral musculature to keep from falling (step on glass, lift up foot and stand on one leg)

Question 37

The gracile fasciculus carries SOME pain fibers. This could explain _______.

Answer 37

why some patients have recurrent pain after anterolateral cordotomy for intractable pain.

Question 38

Disruption of GVE fibers from the IML via a lesion of hypothalamospinal fibers in upper levels of cervical cord and medulla will produce ________

Answer 38

ipsilateral ptosis, miosis, anhidrosis, enophthalmos (Horner syndrome)

Question 39

Why can a high cervical cord lesion be deadly?

Answer 39

Phrenic nucleus is C3-7 in central region of anterior horn - preservation of breathing can become an issue