All of the following must be present:
(1) lower motor neuron (LMN) signs in at least 2 limbs (including the head and neck as 1 limb)
(2) upper motor neuron (UMN) signs in at least 1 region (bulbar, cervical or lumbosacral)
(3) progression of the disease, with increasing symptomatic involvement by history
where:
• Lower motor neuron signs consisted of EMG findings of fibrillation potentials or positive sharp waves in at least 2 separate muscles within the affected limb. For the head only a single cranial-innervated muscle was required. Neither muscles in the foot nor paraspinal muscles were used.
• Upper motor neuron signs include extensor plantar responses, increased muscle tone, spasticity, or pathologic hyperreflexia
• Pathologic hyperreflexia includes clonus, vertical spread of reflexes, horizontal spread of reflexes, or Hoffmann's sign. A brisk reflex without clonus or spread did not constitute a positive finding.
• Upper motor neuron signs in the bulbar region included hyperactive gag reflex, hyperactive jaw jerk, emotional lability, spastic dysphonia, and slowed, rapid alternating movement of the tongue (in the absence of tongue atrophy or fasciculations).
All of the following must be absent:
(1) sensory signs (except those attributable to normal aging)
(2) neurogenic sphincter abnormalities
(3) clinical evidence of another CNS disease with a natural history of progression
(4) clinically evident peripheral nervous system disease with a natural history of progression
(5) structural spinal cord lesions including spondylotic myelopathy
(6) multifocal motor neuropathy
(7) hyperthyroidism
(8) hyperparathyroidism
(9) monoclonal gammopathy associated with a hematologic malignancy
(10) lead poisoning
(11) history of radiation to the brain or spinal cord
(12) hexosaminidase A deficiency (for patients under the age of 30)
where:
• Exclusion items 5 to 12 are referred to as "ALS-like" conditions.
