Amyotrophic Lateral Sclerosis


- See: - El Escorial Revisited: Revised Criteria for the Diagnosis of Amyotrophic Lateral Sclerosis

      - Disorders of Nerves:
      - Anterior Horn Cell Disorders:
      - ALS Society Homepage

- Discussion:
    - amyotrophic lateral sclerosis is a syndrome characterized by both upper and lower motor neuron disease;
            - destruction of anterior horn cells & descending corticospinal tracts;
            - some patients will demonstrate more upper motor neuron disease where as others show more lower motor dz;
    - disease is generally acquired and etiology is unknown;
    - most common in middle & later life & rarely occurs in childhood;
    - clinical course:
            - symptoms include progressive muscle wasting, weakness, & fasciculations;
            - symptoms may begin in arms or legs or may begin with slurred speech;
            - muscles are affected randomly, but eventually respirator failure develops;
            - in 25% of pts the dz is slowly progressive, however, most pts follow a more fulminant course to early death;
    - diff dx: it is important to consider other conditions since these can be successfully treated;
            - multifocal motor neuropathy
                  - can be treated with cyclophosphamide or IV immune globulin;
            - cervical spondylotic myelopathy
            - X-linked spinobulbar muscular atrophy
                  - (Kennedy's disease): slowly progressive lower motor neuron disease of the proximal limbs, usually affecting the upper extremities and bulbar muscles;
            - myasthenia gravis
            - lead intoxication
            - lyme disease


- Exam:
    - clinical presentation is often painless weakness of the arms or legs;
    - manifests with lower motor neuron symptoms of muscle wasting, weakness, and fasciculation;
    - contralateral limb may have hyperreflexia;
    - the ocular muscles and voluntary muscles to the bladder and bowel are often spared;
    - sensation is always normal; 
    - clonus: 
          - Clonus after a Stroke


- Biopsy:
    - muscle bx is particularly useful in dx of spinal muscular atrophy or amyotrophic lateral sclerosis.
    - degeneration occurs in small clusters of fibers (small group atrophy).
    - later on, larger numbers of axons degenerate;
    - those fibers supplied by axons not yet involved remain normal;

- EMG Findings:
    - normal or low compound motor action potentials
    - normal sensory-nerve action potentials
    - evidence of both active (fibrillation potentials, positive sharp waves, and fasciculation potentials)
    - chronic (large-amplitude, large-duration motor-unit action potentials) denervation in multiple sites without conduction block


References

Amyotrophic Lateral Sclerosis

Case records of the Massachusetts General Hospital. Case 22-2006--a 77-year-old man with a rapidly progressive gait disorder.

Study Says Brain Trauma Can Mimic A.L.S.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Clifford R. Wheeless, III, MD on Monday, February 25, 2013 1:33 pm