(Kiosk 1) Unusual Presentation of Amyotrophic Lateral Sclerosis in a Patient with Recurrent Prostate Cancer: A Case Report

Case Diagnosis: A 75-year-old male with unusual presentation of Amyotrophic Lateral Sclerosis (ALS) in the setting of biochemically recurrent prostate adenocarcinoma status post radical prostatectomy, pelvic lymphadenectomy, and androgen deprivation therapy.

Case Description or Program Description: Patient with recurrent prostate adenocarcinoma presented to cancer rehabilitation clinic with new constipation, xerostomia, difficulty rising from a chair, and upper extremity twitching. Examination revealed bilateral atrophy in first dorsal interosseous muscles and weakness in axial muscle groups, deltoids and hip flexors. Differential diagnosis included paraneoplastic syndromes, myasthenia gravis, metabolic syndromes, chemotherapy-related myopathies, and metastases. Though not commonly associated with prostate cancer, Lambert-Eaton myasthenic syndrome was considered given his proximal weakness and autonomic dysfunction. Laboratory studies revealed an elevated sedimentation rate, c-reactive protein, and positive double-stranded deoxyribonucleic acid suspicious for rheumatologic disease. Antinuclear antibody, rheumatoid factor, and creatine kinase were normal. Electromyography (EMG) revealed lower motor neuron disorder affecting the cervical, thoracic, and lumbosacral segments and diffuse fasciculations and fibrillations, highly suspicious of ALS. There was no evidence of myopathy or neuromuscular junction disorder.

Setting: Cancer rehabilitation clinic

Assessment/Results: Patient was diagnosed with ALS and started on riluzole. Multidisciplinary management includes nutritional supplementation, speech language therapy with voice mapping, occupational therapy addressing home equipment needs, respiratory status management, and physical therapy.

Discussion (relevance): This case highlights the complexities of diagnosing ALS in a patient with recurrent cancer. New proximal weakness, twitching, and xerostomia should warrant consideration of ALS amongst the differential in a cancer patient. By initiating prompt laboratory workup and EMG, an accurate diagnosis expedited crucial treatment and rehabilitation interventions to improve quality of life and survival time.

Conclusions: Cancer rehabilitation physicians play a critical role in early recognition and timely diagnosis of disorders like paraneoplastic syndromes and neurodegenerative diseases that can be severely debilitating, difficult to diagnose, and challenging to treat. Patients with a cancer history and concurrent ALS require unique rehabilitation considerations.