Neuroscience Week 3: Spinal Cord Lesions Flashcards
Spinal Muscular Atrophy Clinical Features
Congenital degeneration of anterior horns of spinal cord
LMN lesions only, symmetric weakness
Floppy Baby with marked hypotonia (flaccid paralysis)
tongue fasciculations
Autosomal recessive inheritance of mutation in SMN1
SMA type 1 is called Werdnig-Hoffmann disease
Spinal Muscular Atrophy
Spinal Lesion Location
- LMN lesions only by degeneration of anterior horns of spinal cord
Werdnig-Hoffmann disease AKA
Spinal muscular atrophy Type 1
Amyotrophic Lateral Sclerosis Clinical Presentation & Pathophysiology
Combined UMN (corticobulbar/corticospinal) and LMN (medullary and spinal cord) degeneration
No sensory or bowel/bladder deficits
Can be caused by a defect in superoxide dismutase 1
LMN deficits due to anterior horn cell involvement (dysarthia, dysphagia, asymmetric limb weakness, fasciculations, atrophy)
and
UMN deficits (pseudobulbar palsy, dysarthria, dysphagia, emotional lability, spastic gait, clonus)
Fatal (COMMONLY KNOWN AS Lou Gehrig Disease)
Amyotrophic Lateral Sclerosis Treatment
Riluzole
Amyotrophic Lateral Sclerosis
Spinal lesion locations
- UMN Corticobulbar/corticospinal
- LMN (medullary and spinal cord)
- LMN due to anterior horn cell involvement
Complete Occlusion of anterior spinal artery Clinical Presentation & Pathophysiology
Spares dorsal columns and Lissauer tract
Mid-thoracic ASA territory is watershed area, as artery of Adamkiewicz supplies ASA below T8
Can be caused by aortic aneurysm repair
Presents with UMN deficit below the lesion (corticospinal tract)
LMN deficit at the level of the lesion (anterior horn),
loss of pain and temperature sensation below the lesion (spinothalamic tract)
Complete Occlusion of anterior spinal artery
Spinal lesion location
- UMN deficit below the lesion (corticospinal tract)
- LMN deficit at the level of the lesion (anterior horn)
- loss of pain and temperature sensation below the lesion (Spinothalamic tract)
Tabes Dorsalis Clinical Presentation & Pathophysiology
Caused by 3° Syphilis
Results from degeneration (demyelination) of dorsal columns and roots → progressive sensory ataxia (impaired proprioception → poor coordination)
+ Romberg Sign and absent DTRs
Associated with Charcot joints, shooting pain, Argyll Robertson pupils
Tabes Dorsalis
Spinal Lesion Location
Degeneration (demyelination) of dorsal columns and roots
Syringomyelia Clinical Presentation & Pathophysiology
Syrinx expands and damages anterior white commissure of spinothalamic tract (2nd-order neurons) → bilateral symmetrical loss of pain and temperature sensation cape-like distribution
seen with Chiari I malformation
Can affect other tracts
Syringomyelia
Spinal Lesion Location
anterior white commissure of spinothalamic tract (2nd-order neurons)
Vitamin B12 Deficiency Clinical Presentation & Pathophysiology
Subacute combined degeneration (SCD) – demyelination of Spinocerebellar tracts, lateral Corticospinal tracts, and Dorsal Columns
Ataxic gait, paresthesia, impaired position/vibration sense
Vitamin B12 Deficiency
Spinal Lesion Location
- Spinocerebellar tracts
- Lateral Corticospinal tracts
- Dorsal columns
Cauda Equina Syndrome Clinical Presentation & Pathophysiology
Compression of spinal roots L2 and below, often due to intervertebral disc herniation or tumor
Unilateral radicular pain, absent knee, and ankle reflex, loss of bladder and anal sphincter control, saddle anesthesia
Cauda Equina Syndrome Treatment
- emergent surgery
- steroids
Poliomyelitis Etiology
- Caused by poliovirus (fecal-oral transmission)
- Replicates in oropharynx and small intestine before spreading via bloodstream to CNS
- The infection causes the destruction of cells in the anterior horn of the spinal cord (LMN death)
Poliomyelitis Clinical Presentation
Signs of LMN Lesion:
- asymmetric weakness,
- hypotonia
- flaccid paralysis
- fasciculations
- hyporeflexia
- muscle atrophy
- Respiratory muscle involvement leads to respiratory failure
Signs of infection: Malaise, headache, fever, nausea, etc.
Poliomyelitis Confirmatory test findings
2 listed
- CSF shows ↑ WBCs (lymphocytic pleocytosis) and slight ↑ of protein (with no change in CSF glucose)
- Virus recovered from stool or throat
Brown-Sequard Syndrome Hemisection of spinal cord findings
- Ipsilateral loss of all sensation at the level of the lesion
- Ipsilateral LMN signs (e.g. flaccid paralysis) at the level of the lesion
- Ipsilateral UMN signs below the level of the lesion (due to corticospinal tract damage)
- Ipsilateral loss of proprioception, vibration, light (2-point discrimination) touch, and tactile sense below the level of lesion (due to dorsal column damage)
- Contralateral loss of pain, temperature, and crude (nondiscriminative) touch below the level of lesion (due to spinothalamic tract damage)
If the lesion occurs above T1, the patient may present with ipsilateral Horner syndrome due to damage of the oculosympathetic pathway
Friedreich Ataxia Etiology
Autosomal recessive trinucleotide repeat disorder (GAA) on chromosome 9 in a gene that encodes frataxin (iron-binding protein)
Leads to impairment in mitochondrial functioning
Friedreich Ataxia Pathophysiology & Clinical Presentation
Degeneration of lateral corticospinal tract (spastic paralysis), spinocerebellar tract (ataxia) dorsal columns (↓ vibratory sense, proprioception), and dorsal root ganglia (loss of DTRs)
Staggering gait, frequent falling, nystagmus, dysarthria, pes cavus, hammer toes, diabetes mellitus, hypertrophic cardiomyopathy (cause of death)
Friedreich Ataxia Age of onset
Presents in childhood with kyphoscoliosis
