The challenge of diagnosing ALS in patients with prior poliomyelitis.

ABSTRACT

Four patients with postpolio syndrome (PPS) developed ALS. Weakness and atrophy started from previously unaffected extremities but, contrary to PPS, spread to all muscles leading to death within 0.4 to 8 (mean 3.9) years. Upper motor neuron signs were absent in the atrophic limbs. Abundant spontaneous activity and group atrophy in newly affected muscles were prominent. ALS can rarely occur in the postpolio population starting de novo rather than as evolution of PPS.