(Kiosk 3) Improvement in Fatigue with Amantadine in a Patient with Functional Neurologic Disorder

Case Diagnosis: Functional Neurologic Disorder

Case Description or Program Description: A 22 y.o. male with PMH of Functional Neurologic Disorder (FND) and asthma who presented with difficulty breathing and gait difficulty. In ED, he was witnessed to have generalized shaking. Noncontrast head CT revealed no acute findings. The shaking aborted by itself without intervention. He noted his symptoms were similar to previous FND symptoms. He was observed in the general neurology service and then transferred to inpatient rehabilitation(IPR). On physical exam, his bilateral upper and lower extremity muscle strength was 5/5, except for bilateral hip flexor of 4/5. The sensation was intact to light touch in all extremities. Proprioception was normal. Reflex exam revealed normal DTRs, no Hoffman’s or Babinski but there were bilateral two beats ankle clonus. Bilateral finger-to-nose and heel-to-shin tests were impaired. During IPR stay, the patient was complaining of fatigue affecting his daily activities and therapies. His CBC, TSH, Iron panel, ferritin, and electrolyte levels were within normal limits. He was started on Amantadine 100 mg daily for fatigue.

Setting: Tertiary care adult hospital

Assessment/Results: After 2 days of starting amantadine, the patient noted improvement in fatigue. Also, his therapist reported improvement in his endurance. Before starting amantadine, he was able to walk on the treadmill at 1 mph for 6 minutes then 4 minutes with rest. It improved to 1.2 mph for 10 minutes without rest after amantadine.

Discussion (relevance): This is the first reported case, to our knowledge, regarding the use of amantadine for fatigue in FND.

Conclusions: This patient with FND experienced improvements in fatigue after treatment with amantadine, but properly designed, randomized, and placebo-controlled clinical trials are needed to evaluate the efficacy and safety of amantadine in more patients with FND and fatigue utilizing standardized measures of activity and patient-reported outcome measures.