BB Lecture 11 Spinal Cord Syndromes Flashcards
Descending Corticospinal tract
- 90% of descending motor pathways decussate (cross) at the level of the pyramids in the medulla and descend into the lateral corticospinal tract
- arm fibers travel medial, leg fibers travel lateral
- descending fibers exert an inhibitory influence on muscle tone and deep tendon reflexes (DTRs)
Ascending spinothalamic tract
Anterolateral system; responsible for pain, temperature and light touch
- runs on Lissauers tract
- crosses at the ventral white commissure (the central canal in the spinal cord segment)
- synapses in the thalamus (ventroposterior lateral nucleus of the thalamus, VPL), then to the somatosensory cortex
- leg fibers travel laterally and arm fibers travel medially (because arm fibers are adding to the spinal cord segment)
Ascending Dorsal columns (medial lemniscus)
responsible for proprioception, virbration, 2 point
-leg fibers travel medially in gracilis and arm is laterally in cuneatus (so opposite)
This is so because gracilis is L2 and up and cuneatus doesn’t start until T2…so cuneatus is when arms are adding their fibers
-ascends up to the lower medulla to terminate in the nucleus gracilis and nucleus cuneatus
-decussation occurs in the lower medulla
-fibers ascend then as the medial lemniscus to the thalamus (VPL), which projects to the primary somatosensory cortex
Sympathetic Pathway
Arise in hypothalamus
Descend ipsilaterally to synapse on the T1-L2 spinal nerves and innervate ipsilateral end organs
Horner’s Syndrome
Example of Sympathetic lesion; ptosis, miosis, anhidrosis;
Cocaine test
-cocaine drips into the eye, you get more stimulation and the pupil large
-if you drop cocain in the eye and there is NO dilation, then there is something fucked up and you have horners
Parasympathetic control
Also affected in spinal cord lesions
Infantile bladder
it fills then empties
Bladder control
under parasympathetic control (detrusor muscle)
- afferent: stretch receptors in smooth muscle wall of bladder send sensory input S2-S4 dorsal roots
- efferent: cell bodies in gray matter of S2-S4 spinal cord segments, parasympathetic stimulation causes contraction of the detrusor muscle in the bladder wall and bladder emptying occurs
- in order for you to fuck up bladder control, lesions need to be BILATERAL
Lesion above pons (in relation to bladder)
Infantile bladder (when bladder fills, reflex empties)
Arterial supply of the spinal cord
Anterior 2/3: supplied by the anterior spinal artery which arises from the vertebral artery
Posterior 1/3: supplied by paired posterior spinal arteries
UMN Symptoms and Signs
- slowness/stiffness (think of hand in contracted state in video…)
- increase tone (spasticity)…spasticity = stiffness
- hyperactive reflexes
- Pathological reflexes such as extensor plantar or Babinski, Hoffman’s, palmomental, pseudobulbar affect
LMN Symptoms and Signs
-weakness and cramps
-Atrophy
-Fasciculations (not the same as spasticity)
-Decreased tone
-Hypoactive Reflexes
ATROPHY especially a sign that you have lost your ventral roots
Complete Cord Transection
MOA:
-trauma
-extrinsic compression (tumor,, abscess, hematoma)
-transverse myelitis (inflammatory)
Outcome depends on level of lesion
-high cervical lesions (C1-C3) require ventilator support
-Sparing C7 retains ability to independently transfer (elbow and wrist extension)
Brown-Sequard Syndrome
Hemisection of the spiinal cord
MOA:
-caused by trauma or extrinsic lesion
-rarely caused by intramedullary lesion
Central Cord Lesions
Caused by syringomyelia, hematomyelia, intramedullary tumor, chiari malformation (which leads to syringomyelia)
Symptoms: BILATERAL lesion of the spinothalamic tract at FIRST
NEXT affects anterior horn cells at level of lesion with LMN findings
Cord damage starts centrally and spreads centrifugally (think of fluid filled hole near central cord of spinal cord)
Posterior Column Syndrome (Tabes Dorsalis)
Lesion of dorsal column MOA: syphilis Symptoms: -ATAXIA (no bilateral proprioception, vibration and 2 point touch) Diagnosis: Romberg’s sign -cannot stand with feet together and eye closed -NOT sign of cerebellar disease -It is a sign of proprioceptive loss
Posterolateral Column Syndrome
MOA:
- lesion of dorsal column and corticospinal tract
- B12 deficiency MOST COMMON
- myelin degeneration
Symptoms:
Loss of proprioception and vibration (Romberg sign)
Spasticity and hyperactive reflexes (corticospinal tract lesion) UMN symptoms
Anterior Horn Cell Disease
Lesion of anterior horn cells (motor neuron cell bodies)
Cause:
- spinal muscular atrophy (SMA)…Inherited or acquired
- Infectious:
a. poliomyelitis
b. West Nile
c. Enterovirus, coxsackie A & B, Echoviruses
Symptoms:
Lower motor neuron findings (weakness, fasciculations, flaccid) at affected segment or can be part of a widespread condition
Combined Anterior Horn Cell - Pyramidal tract Syndrome (ALS)
Lesion of both UMN and LMN
Symptoms:
Combined UMN and LMN findings without alternative etiologies (both spasticity and fasiculations)
UMN and LMN in the absence of an identified cause
Anterior Spinal Artery Occlusion
Lesion of corticospinal and spinothalamic tract
Dorsal column intact
Symptoms:
-flaccid weakness then spastic paraparesis (spinal shock causes former while corticospinal tract causes latter)
-loss of pain and temperature below lesion
-LMN abnormalities at level of lesion
-lost bowel and bladder function
-preservation of dorsal column functions
Intramedullary Lesion (mass lesion)
means within the spinal cord
initial symptoms reflect parenchymal involvement with early segmental sensory and motor shit
Example: glioblastoma, myelitis, abscess, astrocytoma
Symptoms: complete cord transection symptoms
Intradural extramedullary lesion (mass lesion)
Schwannoma
-Meningioma
Symptoms: you can go from brown-sequard to complete cord transection
Extradural lesion (mass lesion)
aoutside dura and pressing on spinal cord caused by lymphoma epidural abscess Disc disease Primary bone tumor Epidural metastasis
Initial symptoms = reflective of root compression
Final symptoms = reflective of complete cord transection
Cervical Myelopathy
Slipped disc
Can cause spinal cord compression at C7 level
If you have a L5 herniation, you will have NOT HAVE a cord syndrome
You can only have a LMN syndrome
-dermatomal sensory loss
-loss/depression of reflexes at affected level
-radicular (root) pain
-no bowel/bladder involvement
Spinal cord compression (mild, moderate, severe)
Mild
-Extrinsic cord compression starts with radicular (ventral and dorsal root) symptoms like hypersensitivity (dorsal root) and loss of pain and temperature (spinothalamic)
Moderate
-contralateral spinothalamic and ipsilateral corticospinal…similar to hemisection (of the same side as tumor)
Severe
-complete cord transection
What do the loss of sensation at a particular dermatome tell you?
The spinal cord segment at which the lesion takes place
Lesion below the pontomesenphalic micturition center and above the conus medullaris
FIRST acute acontractile bladder (urinary retention)
THEN chronic spastic bladder (urinary frequency, urgency and urge incontinence)
MOA of chronic spastic bladder: loss of inhibitory influences on the detrusor wherein stretch of the bladder wall even with INCOMPLETE filling causes reflex detrusor contraction and emptying
Pontomesenphalic micturition center
area in the pons that controls micturition
Bilateral Lesions of sacral dorsal roots, cauda equina and conus medullaris
Symptoms: atonic bladder
- flaccid loss of sensation
- dribbling
- overflow incontinence
Spasticity
Stiffness
Babinski’s sign
In Adults:
Normal: tickling of foot causes flexion of toes
Abnormal: tickling of foot causes extension of toes
Abnormal = UMN lesion
Exceptions: Infants show extensor response up until 12 to 24 months of age because their corticospinal pathways are not fully myelinated
Sensory localization and segmental sensory loss
Look for loss of sensation at that dermatome and below
OR
-loss of sensation in one or more adjacent dermatomes with preservation above and below that level
Complete Cord Transection Symptoms
Motor: loss of all motor function below lesion
Sensory: Loss of all sensory function below lesion
Pinprick may be a few levels below lesion because of Lissauer’s tract in spinothalamic tract
Autonomic: bowel and bladder dysfunction
Acute (mimics acute symptoms we would expect from a pontomedullary micturition center to conusmedullaris lesion)
-flaccid plegia (weakness)
-urinary retention and constipation
Chronic (mimics chronic symptoms of intermediate bladder control lesion0
-spastic plegia
-spastic bladder and rectal sphincter (so incontinent)
Brown-Sequard (hemisecton) Symptoms
Motor:
-ipsilateral below lesion…both UMN and LMN signs (flaccid weakness that turns into spastic weakness over time)
Sensory:
- contralateral pain/temp/fine touch deficit (1-2 levels below lesion…lissauer’s tract)
- ipsilateral prop/vibration/2 point touch
Autonomic:
-no bowel and urinary symptoms because you need BILATERAL lesion in order for bladder get problems
Chiari Malformation
Congenital Malformation
Herniation of cerebellar tonsils through the foramen magnum
Syringomyelia
damage to the spinal cord due to a fluid-filled hole that forms in the cord
Hematomyelia
an effusion of blood into the spinal cord
Romberg’s sign
Tests for proprioceptive loss; not specific for cerebellar lesion; is seen when patient cannot balance him or herself with eyes closed
