Spinal Cord Flashcards
What is myelopathy?
• Myelopathy: Disorder resulting in spinal cord dysfunction.
What is a nerve root?
o Nerve Root: Combined sensory and motor rami of the spinal cord (e.g. L5)
What is a tract?
o Tracts: Axons that travel in the spinal cord to relay information. (e.g. corticospinal tract).
What is a hyperesthesia?
Hyperesthesia: Abnormal acuteness of sensitivity to touch, pain, or other sensory stimuli
What is a dysesthesia?
o Dysesthesia: Impairment of sensation short of anesthesia
What is a parasthesia?
o Paresthesia: An abnormal sensation, can include burning, pricking, tickling, or tingling. Sometimes characterized as “pins and needles”
What is an intervertebral foramen?
o Intervertebral foramen: Opening formed by 2 adjacent vertebral bodies through which the nerve roots travel.
What is a radiculopathy?
o Radiculopathy: Sensory and/or motor dysfunction due to injury to a nerve root.
What is a myotome?
o Myotome: Muscles innervated by an individual motor root.
What is a dermatome?
o Dermatome: Cutaneous area served by an individual sensory root.
How many pairs of nerve roots are there coming from what spinal levels?
31 pairs of nerve roots (8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral, 1 Coccygeal).
There are 7 cervical vertebrae, but how many cervical nerves?
8 cervical nerves, to 7 cervical vertebrae.
- for all cervical levels, the X cervical spinal nerve exits ABOVE the vertebral body.
- for thoracic nerves and below, the X spinal nerve exits BELOW the vertebral body
- the only trick then to remember is C7 has the 7th spinal nerve above it and the 8th spinal nerve below it (C8)
- C8 = spinal nerve C8, never the vertebral body C8
What’s the general rule of thumb to use when keeping track of vertebral body level injuries correlating to spinal cord level injuries?
• Upper cervical
○ Vertebra # overlies same cord segment #
• Lower cervical
○ Vertebra # overlies cord segment +1 (C6 is over C7)
• Upper thoracic
○ Vertebra # overlies cord segment +2 (T4 is over T6)
• Lower thoracic/lumbar
○ Vertebra # overlies cord segment +2-3 (range)
§ T11 overlies L1-2 cord
§ The vertebral bodies are bigger at that point than the spinal cord segments
• Lower edge of the L1 vertebral body overlies the cord tip (conus medullaris)
○ Thus the lumbar puncture)
What spinal cord levels make up the conus medullaris?
- S3-S5
- Tip of the cord
- Supplies bladder, rectum, genitalia
What does the conus medullaris innervate?
- S3-S5
- Tip of the cord
- Supplies bladder, rectum, genitalia
- Remember these exit the cord way lower, but the spinal cord levels are higher up, within the 4th and 5th lumbar vertebral area
What spinal cord levels make up the cauda equina?
• LS roots within the lumbosacral cistern
Because of the organization of the spinal cord tracts, what will an extramedullary tumor present as?
- Early UMN problems
- Early pain
- Pain and temp loss in an ascending fashion
Because of the organization of the spinal cord tracts, what will an INTRAmedullary tumor present as?
- Early bladder dysfunction
- Late development of pain
- Even later development of UMN syndrome
- Temperature and pain loss is a descending pattern (cervical first, then down)
The spinothalamic tract is organized how?
• With bundles moving from medial to lateral
○ Whole thing is anterolateral tract, pain and temperature from the contralateral side
• Cervical (medial), then thoracic, lumbar and sacral moving lateral
• Thus intrameddullary lesion has pain and temp loss in a descending pattern
What spinal cord structure is organized (from medial to lateral) in an ascending manner?
- The Dorsal column/lemniscal system
- Fasciculus gracilis (fine touch, vibration, proprioception) is medial and the fasciculus cuneatus is more lateral
- Thus an intramedullary lesion in the dorsal spinal cord will produce fine touch loss in an ascending pattern
The lateral corticospinal tract is organized how?
- These are upper motor neurons on the lateral side of the grey matter
- Organized with cervical levels most medial and progressing lateral to sacral UMNs
- Thus an intrameddullary lesion would cause UMN syndrome in a descending manner
- Extramedullary lesion would cause UMN syndrome in an ascending manner
Following the normal dermatome map is great, but you must remember one detail…?
• Variations are common, and a persons variation is +/- one full dermatome
What are the major dermatomal landmarks?
- Top of head = C2
- Side of face = C3
- Neck = C3/4
- Nipples - mark T4 and T5 border
- Umbilicus - mark T10 and 11 border
- Back of shoulder and lateral arm = C5
- Thumb and 2nd digit = C6
- Third digit (middle finger) = C7
- Last two fingers = C8
- Medial arm (medial bicep region) = T1/2
- Knee region (medial) - L3/4
- Shins - L4/5
- Great toe and dorsal foot - L5
- Lateral foot, small toe, bottom foot - S1
The observational part of the neuro exam is looking for what?
- Atrophy,
- Hypertrophy
- Fasciculations
- Tremor
- Involuntary movements
In passive movement, you may find spasticity in a certain muscle group. What does this look like?
- Velocity dependent increase in muscle tone
* You are moving the limb and it all of a sudden starts resisting (sometimes jerkily)
What are the upper extremity muscle testing maneuvers?
- Shoulder abduction
- Elbow flexion and extension
- Wrist flexion and extension
- Finger abduction
What are the LOWER extremity muscle testing maneuvers?
- Hip flexion
- Knee flexion and extension
- Leg abduction
- Foot dorsiflexion and plantar flexion
- Great toe dorsiflexion
In muscle testing (neuro exam) you assign a grade for muscle strength out of 5. What is the scale?
- 0 - paralysis
- 1 - muscle flicker, no movement
- 2 - movement is possible, but struggles aganst gravity
- 3 - movement possible against gravity, not resistance
- 4 - movement is possible against some resistance
- 5 - normal strength
What is the reflex grading system?
- 0 - reflex is absent
- 1+ - trace
- 2+ - normal
- 3+ - brisk
- 4+ - nonsustained clonus (repetitive vibratory movements)
- 5+ - sustained clonus
How do you elicit the plantar response?
• Flexor, extensor or ambivalent
○ Extensor = babinski sign
• Scraping an object across the sole of the foof from the heel toward the small toe
• Then arcing toward big toe
• Normal response = flexion of toes
• Abnormal response = extension big toe and fanning of the others
○ Babinski sign (indicates UMN problem)
• Hoffman sign - abnormal response in upper extremity
What syndrome is indicated in a scissoring of both legs upon tapping the medial aspect of the adductor tendons?
- UMN syndromes
* Crossed adductor response
The reflexes you have to know completely are…?
• Biceps ○ C5 root ○ 10% of UE radiculopathies • Bracioradialis ○ C6 root ○ 20% of UE radiculopathies • Triceps ○ C7 root ○ 50% of UE rediculopathies • Patellar ○ L4 root ○ 10% of LE rediculopathies • Achilles ○ S1 root ○ L5-S1 level ○ 45% of LE rediculopathies • (not a reflex, but an motor group) ○ Foot dorsiflexion, big toe extension, foot eversion and inversion ○ L5 root ○ 40% of LE rediculopathies • Babinski sign ○ Extension of big toe and fanning of other toes when scraping bottom of foot ○ Indicative of UMN syndromes
When worried about the C5 root what motor functions do you examine?
• Deltoid
• Infraspinatus
• Biceps
○ Biceps reflex
When worried about the C6 root what motor functions do you examine?
• Wrist extension
• Biceps
○ Biceps and brachioradialis reflexes
When worried about the C7 root what motor functions do you examine?
• Triceps
○ Triceps reflex as well
When worried about the S1 root what motor functions do you examine?
• Foot plantarflexion
○ Achilles reflex
When worried about the L5 root what motor functions do you examine?
• Foot dorsiflexion • Big toe extension • Foot eversion • Foot inversion ○ No reflex to examine
When worried about the L4 root what motor functions do you examine?
• Psoas
• Quads
○ Patellar reflex
What disc is usually involved in a C5 root problem?
• C4-5 disc
What disc is usually involved in a S1 root problem?
• L5-S1
What disc is usually involved in a L5 root problem?
• L4-5
What disc is usually involved in a L4 root problem?
• L3-4
What disc is usually involved in a C7 root problem?
• C6-7
What disc is usually involved in a C6 root problem?
• C5-6
If you find a sensory abnormality in:Shoulder, upper lateral arm
• Look for damage to C5
If you find a sensory abnormality in:Lateral foot, small toe and sole of foot
• Look for damage to S1
If you find a sensory abnormality in:Dorsum of foot and great toe
• Look for damage to L5
If you find a sensory abnormality in:Knee, medial leg
• Look for damage to L4
If you find a sensory abnormality in:3rd digit
• Look for damage to C7
If you find a sensory abnormality in:1st and 2nd digits of hand
• Look for damage to C6
In a complete cord transsection, what are the tracts affected and what is the expected deficit?
- All ascending sensory tracts
- All descending motor tracts
- Sensory + motor levels below lesion are lost
- Spinal shock followed by UMN syndrome
In a central lesion what tracts are effected and what’s the expected deficit?
• Tracts
○ Initially involve crossing Spinothalamic tract
§ Pain and temp
• Deficit
○ PP/Temp loss at level of lesion with sparing of proprioception
• Note
○ Cape-like distribution if in C-spine
• Possible cause
○ Syringomyeli (fluid filled cavity in cord)
In a posterior column syndrome what tracts are affected and what’s the expected deficit?
• Tracts ○Posterior column/Medial Lemniscus Fine touch and prop • Deficit ○ bilateral loss of position and vibration sensation • Note ○ temp and pain are in place • Possible cause ○ tabes dorsalis (form of neurosyphilis)
In combined anterior horn cell-pyramidal tract syndrome what are the tracts affected and what is the expected deficit?
• Tracts ○ CS and LMN cells in the cord § Motor problems • Deficit ○ Loss of bilateral muscle strength • Note ○ Fasciculations, atrophy, either repressed or hyperactive DTR, normal sensation • Possible cause ○ Amyotrophic lateral scleoris = ALS
In Brown-sequard syndrome what are the tracts affected and what is the expected deficit?
• Tracts ○ Crossed ST + uncrossed PC + Crossed CS § Hemi-section of cord • Deficit ○ Below lesion, § loss of CL PP/temp § Loss of IL position § Loss of IL strength
In posterior cord syndrome what are the tracts affected and what is the expected deficit?
• Tracts
○ PC + CS
• Deficit
○ Bilateral loss of position + vibration + strength
• Possible cause
○ B12 deficiency (subacute combined degen)
In anterior horn cell syndrome what are the tracts affected and what is the expected deficit?
• Tracts
○ No tracts, just LMN cells
• Deficit
○ Loss of bilateral muscle strength
• Note
○ Fasciculations, decreased tone, depressed DTR’s
○ Spares all sensory tracts and bladder function
• Possible cause
○ Spinal muscular atrophy - polio virus
In anterior spinal artery occlusion what are the tracts affected and what is the expected deficit?
• Tracts ○ ST + CS § Pain/temp, motor • Deficit ○ Loss of bilateral muscle strength + loss of PP/Temp ○ Sparing of position and fine touch
In pyramidal tract syndrome what are the tracts affected and what is the expected deficit?
• Tracts ○ CS § Motor problems • Deficit ○ Bilateral UMN syndrome ○ Increased DTRs ○ Complete sparing of all sensory tracts and bladder function • Possible cause ○ Primary lateral sclerosis
In myelopathy with radiculopathy what are the tracts affected and what is the expected deficit?
• Tracts ○ Any or all tracts, but especially CS § Motor problems in particular • Deficit ○ Bilateral UMN syndrom, spastic gait ○ Hyperactive DTRS ○ IL or CL root signs ○ Possible bladder dysfunciton • Possible cause ○ Cervical spinal stenosis, congenital or degen
What is the difference between conus medullaris problems and cauda equina syndrome?
• Conus ○ Late pain in thighs and butt ○ Pelvic flor muscle weakness ○ Symmetric saddle anesthesia ○ Early bladder dysfucntion ○ Early bowel and sexual dysfunction • Cauda equina ○ Early root pain radiating to legs ○ Leg weakness and decreased DTRs (LMN) ○ Patchy, asymmetric saddle anesthesia ○ Late bladder dysfunction ○ Late bowel and sexual dysfunction
What are the three main components of bladder continence control?
• Detrusor muscle ○ Smooth muscle ○ Activated by preganglionic parasympathetic outflow from S2-4 • Sphincter ○ Smooth muscle ○ Sympathetic outflow from T10-L2 • Pelvic floor ○ Skelatal muscle ○ Innervated by alpha motor neurons from S2-4
What happens neurologically as the bladder increases?
- Afferent information from muscle spindles and sensory in bladder wall
- Activates higher centers in brainstem and cortex
- Send info down the medial LCST and coordinate inhibition of sympathetic tone and activaiton of parasympathetic contraction of the detrusor
- Voluntary sphincter prevention of voiding is under control of frontal cortex via descending inputs to alpha motorneurons in anterior horn of S3,4 (descending alont LCST)
What is onufs nucleus?
- Involved in voluntary bladder control
- Voluntary sphincter prevention of voiding is under control of frontal cortex via descending inputs to alpha motorneurons in anterior horn of S3,4 (descending alont LCST)
What’s going on in flaccid bladder?
- Overflow incontinence b/c body doesn’t recognize when bladder is full
- Parasymp LMN are injured
- Weakness, atrophy, hyporeflexia
What’s going on in spastic bladder?
- UMN syndrome of bladder control
- Descending pathway so bladder control are injured
- Initial flaccidity of bladder, followed by contractions due to small degrees of stretch
- Result is urgency and frequency
- Can also desynch the symp and para coordination, leading to kidney damage by ureteral reflux
Presence of Lhermittes sign indicates what?
• Neck flexion results in electric shock sensation down back and into arms
○ Lhermitte sign
• Attributed to posterior column disease
○ MS, disc, B12 deficiency, posterior cord mass
What would cervical stenosis result in?
• UMN signs in legs +/- bladder dysfunction
Spinal shock is loss of all spinal cord function after an injury. What are the 4 phases?
• 1 - complete loss of all reflexes below injury level
○ One day course, hyperpolarization due to lack of normal basal stimuli from brain
• 2 - over next two days
○ Return of some, not all, reflexes below injury
○ Polysynaptic reflexes first (bulbocavernosus)
○ More receptors for NT are expressed in muscles
• 3 and 4 - next couple weeks
○ Hyperreflexia
○ Interneurons and lower moter below injury begin sprouting and re-establishing synapses
○ First to form are shorter axons from interneurons
• 4 - chronic spasticity stage, one month out and possibly forever
○ Soma-dependent
What is neurogenic shock?
• Don’t confuse with spinal shock
• Low blood pressure and slow heart rate
• Disruption of ANS within spinal cord
• Hypotension results from decreased systemic vascular resistance
○ Loss of sympathetic tone
• Bradycardia from unopposed vagal tone
