Section 7 - Spinal Cord Flashcards
What is amyotrophic lateral sclerosis?
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.
What is myasthenia gravis?
Autoimmune abnormality where antibodies bind to the nicotinic acetylcholine receptors at neuromusclar jxn, blocking normal effects of acetylcholine to depolarize muscle and elicit response.
List symptoms of myasthenia gravis.
- 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
What is syringomyelia?
Cavitation of central region of spinal cord. NOT the central canal.
A small syrinx damages:
Fibers crossing anterior white commissure (ALS); damage ALS tract destined bilaterally to specific spinal levels. (2 levels below, bilaterally).
A large syrinx damages:
Anterior white commissure AND anterior horn –> bilateral sensory loss at specific levels, weakness of extremity
What is a hydrosyringomyelia?
A cavitation of the central canal.
Non-communicating syringomyelia ______.
Communicating syringomyelia ______.
- Is separate from the central canal.
- Has a cystic structure connecting to the central canal.
What is Brown-Sequard Syndrome?
A hemisection of the spinal cord that reflects damage to lateral corticospinal tract, ALS, and dorsal columns.
List symptoms of Brown-Sequard Syndrome.
- Muscle weakness/paralysis ipsilaterally
- Loss of pain and thermal sensation contralaterally
- Loss of proprioception, vibratory, fine touch ipsilaterally
What is a radiculopathy?
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).
What is a mononeuropathy?
Damage to defined peripheral nerve, often from trauma or entrapment (like carpal tunnel). Leads to paresthesia, pain, weakness in target tissue.
List some characteristic examples of a mononeuropathy.
- Tongue deviation (XII)
- Flexion/adduction, extension of fingers (ulnar)
- Foot dorsiflexion (fibular)
- Forearm pronation (median)
- Flexion of toes (tibial)
What is a polyneuropathy?
Damage in multiple peripheral nerves, so both motor and sensory.
What is glove and stocking sensory loss?
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
What is a motor neuropathy, and what does it lead to?
- Loss of anterior horn motor neurons
- Flaccid weakness, muscle fasciculations, muscle atrophy
What is a sensory neuropathy, and what does it lead to?
- Loss of cell bodies in DRG
- Distal and proximal extremity affected
What is a lower-motor lesion?
- Skeletal mm. activity affected (the final common pathway)
- FLACCID paralysis, muscle ATROPHY, diminished or ABSENT deep tendon reflexes
What is an upper-motor lesion?
- 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
What results from occlusion/spasm of anterior spinal artery (Central Cervical Cord Syndrome)?
- Bilateral weakness of extremities (mostly upper)
- Patchy loss of sensation below lesion
- Urinary retention
What is poliomyelitis?
Viral infection leading to spinal cord inflammation of gray matter
What are symptoms of poliomyelitis?
- Headaches
- Red/sore throat
- Slight fever
- Vomiting
- Abnormal reflexes
- Back/neck stiffness
What is tabes dorsalis?
Slow degeneration of sensory neurons in dorsal columns of spinal cord. Occurs as secondary demyelination due to untreated syphilis.
What are symptoms of tabes dorsalis?
- Weakness
- Diminished reflexes
- Paresthesias
- Hypoesthesias
- Progressive locomotor ataxia
What is spinal shock?
Loss of sensation accompanied by motor paralysis with gradual recovery of caudal reflexes following a spinal cord injury
What is deafferentiation pain?
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
How do we treat deafferentiation pain?
DREZ (dorsal root entry zone) procedure - radiofrequency lesions made at levels of avulsed or lesion roots
What are possible consequences of DREZ?
- Can damage corticospinal tract and/or cuneate tract
- Weakness of extremity on same side
- No proprioception, vibration on ipsilateral side (buzzing)
What is neuropathic pain?
Results from damage/disease affecting somatosensory system, continuous or episodic - pain is produced by non-painful stimuli (allodynia) and associated with abnormal sensations (dysesthesia).
Describe Acute Central Cervical Spinal Cord Syndrome (or Central cord syndrome).
Incomplete spinal cord injury from traumatic hyperextension of cervical spine or mechanical injury –> bilateral damage to cervical spinal cord (anterior spinal artery)
Signs of central cord syndrome?
- 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)
What is the deep tendon reflex?
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)
What is the inverse myotatic reflex?
Autogenic/reciprocal inhibition - One group of muscles is excited and the antagonistic group is inhibited
What is the Golgi tendon organ?
Responsible for autogenic inhibition; requires greater strength of stimulus (a higher muscle tension) for action than the muscle stretch (myotatic) reflex
What is the flexor reflex?
Initiated by cutaneous input (nociceptive stimuli); responds to attempt to protect the body
What is the crossed extension reflex?
Builds on circuit of flexor reflex; involves contralateral musculature to keep from falling (step on glass, lift up foot and stand on one leg)
The gracile fasciculus carries SOME pain fibers. This could explain _______.
why some patients have recurrent pain after anterolateral cordotomy for intractable pain.
Disruption of GVE fibers from the IML via a lesion of hypothalamospinal fibers in upper levels of cervical cord and medulla will produce ________
ipsilateral ptosis, miosis, anhidrosis, enophthalmos (Horner syndrome)
Why can a high cervical cord lesion be deadly?
Phrenic nucleus is C3-7 in central region of anterior horn - preservation of breathing can become an issue
