1537 - Coexistence of Chronic Sensorimotor Neuropathy and Amyotrophic Lateral Sclerosis: Clinical Features and Diagnostic Challenges

Case Diagnosis: ALS is a progressive neurodegenerative disease of upper and lower motor neurons. Coexistence with distal sensory polyneuropathy is rare and can delay diagnosis, especially when sensory symptoms appear first. This case emphasizes the value of comprehensive neurophysiological evaluation.

Case Description:

A 66-year-old man with a 25-year history of progressive motor and sensory deficits initially presented with lower limb weakness, wheelchair dependence, and incontinence. Over 18 months, he developed asymmetric proximal upper limb weakness, head drop, dysarthria, and mild dysphagia. Exam showed distal and proximal atrophy, cervical fasciculations, hand weakness, foot drop, truncal weakness, and stocking-glove sensory loss. Reflexes were brisk with bilateral Babinski and Hoffmann signs. EMG showed length-dependent sensorimotor axonal polyneuropathy plus active denervation in proximal limbs and thoracic paraspinals, suggesting superimposed motor neuron disease.Imaging revealed multi-level cervical stenosis and lumbosacral degeneration. Labs showed borderline B12 and folate, positive anticardiolipin IgM, and prior Hepatitis C. The patient was diagnosed with ALS per Gold Coast criteria.

Discussions: This case highlights the diagnostic challenge of long-standing polyneuropathy with bulbar symptoms, proximal weakness, head drop, and fasciculations suggesting motor neuron disease. Electrophysiology revealed dual pathology: chronic length-dependent axonal changes accounting for longstanding distal sensory loss, and new asymmetric denervation in proximal limb and thoracic paraspinal muscles, indicating a motor neuron process. While neuropathy typically precedes ALS by only months to a few years, this patient’s decades-long course raises consideration of a hereditary neuropathy–ALS overlap. The absence of family history or genetic testing leaves alternative explanations, including coincidental dual pathology given risk factors such as hepatitis C and prior substance use. Fasciculations, head drop, and EMG evidence of proximal asymmetric denervation beyond typical neuropathy support a superimposed motor neuron disease.

Conclusions: The rare coexistence of long-standing sensorimotor polyneuropathy and ALS highlights the need for vigilance, long-term follow-up, and comprehensive re-assessment as new symptoms emerge.