Visual Hallucinations & Loss of Taste/smell in the Setting of Progressive Dyspnea, Muscular Atrophy, Painless Upper Extremity Weakness in a Patient with Suspected Genetic Amyotrophic Lateral Sclerosis

Case Diagnosis: 80-year-old male with past medical history significant for chronic obstructive pulmonary disease clinically diagnosed with a frontal variant of amyotrophic lateral sclerosis (ALS).

Case Description or Program Description: He presented with a several-month history of progressive dyspnea, muscular atrophy, painless upper extremity weakness, loss of taste/smell, and new visual hallucinations. He further reported an associated 45-pound weight loss over this time. Patient was admitted to the hospital due to difficulty breathing following a sedated CT scan. He required intubation and was transferred to the medical intensive care unit where he was unable to wean from the ventilator.

Setting: Tertiary Care Hospital

Assessment/Results: Physical examination revealed greatest weakness in bilateral upper extremities while distal lower extremities were relatively preserved. MRI of the cervical spine was notable for nonspecific findings within the posterior paraspinal muscles. CSF exam was generally unremarkable. Alpha-Glucosidase level was within normal limits. Electrodiagnostic (EDX) testing revealed diffuse denervation in a right craniobulbar muscle (frontalis), multiple extremities (cervical and lumbosacral regions), and thoracic paraspinals. The patient met Gold Coast criteria for diagnosis of ALS. In addition, his loss of taste and smell, and his visual hallucinations are consistent with frontal lobe dysfunction. The final diagnosis of the patient's clinical picture is most consistent with a frontal variant of ALS.

Discussion (relevance): Painless progressive weakness is a common symptom associated with ALS – the most common of all motor neuron disorders. Frontal Lobe symptoms are rare, however, they're linked to a frontal variant of ALS associated with a mutation in the C9orf72 gene.

Conclusions: Physiatrists who perform EDX testing need to keep a broad differential and be aware of possible variants to allow for appropriate diagnosis and optimal management. The frontal variant of ALS is commonly associated with a mutation in the C9orf72 gene, therefore increasing awareness of this unique presentation of ALS may lead to earlier testing and diagnosis.