Flashcards in Lesions of the Spinal Cord - HY Deck (32):
How are UMN lesions caused?
By transection of corticospinal tract OR destruction of the cortical cells of origin.
What is the result of UMN lesions?
Spastic paresis with pyramidal signs (Babinski's sign).
How are LMN (lower motor neuron) lesions caused?
By damage to the motor neurons.
What is the result of LMN lesion?
1. Flaccid paralysis
How do polio or Werdnig-Hoffmann disease occur?
From damage to the motor neurons.
Give an example of combined UMN and LMN disease.
ALS - Lou Gehrig's disease.
What neurons are damaged in ALS?
Damage to the corticospinal tracts, with pyramidal signs, and to LMNs, with LMNs symptoms.
NO SENSORY DEFICITS.
Give an example of sensory pathway lesion.
Tabes dorsalis (dorsal column disease) --> seen in patients with neurosyphilis.
What characterizes dorsal column disease (tabes dorsalis)?
1. Loss of tactile discrimination and position.
2. Vibration sensation.
In tabes dorsalis, what is the result of irritative involvement of the dorsal roots?
Pain + paresthesias.
What sign is positive in tabes dorsalis?
What is the Romberg sign?
Subject stands with his feet together and, when he closes his eyes, loses balance --> This is a sign of dorsal column ataxia.
What is basically the Brown-Sequard syndrome?
Spinal cord hemisection.
How is Brown-Sequard caused?
By damage to the following structures:
1. Dorsal columns (gracile (leg) and cuneate (arm) fasciculi).
2. Lateral corticospinal tract.
3. Lateral spinothalamic tract
4. Hypothalamospinal tract at T1 and above.
5. Ventral (anterior) horn.
What is the result of ventral spinal artery occlusion?
Infarction of the anterior 2/3 of the spinal cord but spares the dorsal columns and horns.
What structures are damaged in ventral spinal artery occlusion?
1. Lateral corticospinal tracts
2. Lateral spinothalamic tracts
3. Hypothalamospinal tract at T2 and above
4. Ventral anterior horns
5. Corticospinal tracts to the sacral PNS centers at S2 to S4.
What causes subacute combined degeneration (vitB12 neuropathy)?
Pernicious megaloblastic anemia.
What structures are damaged in subacute combined degeneration?
1. Dorsal columns
2. Lateral corticospinal tracts
3. Spinocerebellar tracts
What is syringomyelia?
Central cavitation of the cervical cord of unknown etiology.
What structures are damaged in syringomyelia?
1. Ventral white commissure
2. The ventral horns
What conditions has the same spinal cord pathology and symptoms as subacute combined degeneration?
What spinal cord lesions do we see in MS?
The plaques primarily involve the white matter of the cervical segments of the spinal cord.
Lesions are random and asymmetric.
Give an example of peripheral nervous system (PNS) lesions.
Guillain-Barré syndrome (acute idiopathic polyneuritis, or post infectious polyneuritis).
What is affected in Guillain-Barré syndrome?
The motor fibers of the ventral roots and peripheral nerves --> Produces LMN symptoms (muscle weakness, ascending flaccid paralysis, areflexia).
What are the major features of Guillain-Barre?
1. Demyelination + edema
2. Upper cervical root (C4) involvement + respiratory paralysis is common.
3. Caudal cranial nerve involvement with facial diplegia is present in 50% of cases.
4. Elevated protein levels may cause papilledema.
5. To a lesser degree, sensory fibers are affected --> paresthesias.
6. Protein level in CSF --> elevated, but without pheocytosis (albuminocytologic dissociation).
Where is intervertebral disk herniation most common?
L4/L5 and L5/S1 (90%)
C5/C6, C6/C7 (10%)
What is the mechanism of the intervertebral disk herniation?
Prolapse, or herniation, of the nucleus pulposus through a defective anulus fibrosus and into the vertebral canal.
What is the mechanism for the symptoms of intervertebral disk hernation (paresthesias, pain, sensory loss, hyporeflexia, and muscle weakness)?
Nucleus pulposus impinges on the spinal roots
How can cauda equina syndrome occur?
From nerve root tumor/ ependymoma/ or a dermoid tumor/ or from a lipoma of the terminal cord.
What characterizes cauda equina syndrome?
1. Severe radicular unilateral pain
2. Sensory distribution in a unilateral SADDLE-SHAPED area.
3. Unilateral muscle atrophy + absent quadriceps (L3) and ankle jerks (S1).
4. Unremarkable incontinence and sexual functions.
5. Gradual and unilateral onset.
How can conus medullaris syndrome occur?
Usually from an intramedullary tumor (ependymoma).