Case reportVisual impairment in Parkinson's disease treated with amantadine: Case report and review of the literature
Introduction
Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease, affecting ∼0.3% of the general population and 3% of people over the age of 65 [1]. The disease is characterized pathologically by loss of dopaminergic neurons in the substantia nigra pars compacta in the midbrain and phenomenologically by parkinsonism such as resting tremor, muscular rigidity, bradykinesia, and postural instability. Amantadine, an antagonist of N-methyl-d-aspartate (NMDA)–glutamate receptor [2], is widely used for the treatment of PD including levodopa-induced dyskinesias [3], since its anti-parkinsonian effects were reported in 1969 [4]. However, there have been few reports in the literature of ocular side effects of amantadine. We describe a rare case of a patient with PD who developed visual disturbance during treatment with amantadine.
Section snippets
Case report
A 61-year-old man presented with gradual left-sided shuffling gait. Twenty-five months after the onset, the patient noticed a mild resting tremor in the left hand and complained of a tendency for the left leg to stumble. He consulted a local neurologist 30 months after symptom onset and was diagnosed with PD. The patient was then started on treatment with amantadine (300 mg/day) and trihexyphenidyl (4 mg/day). At age 64, he was referred to the outpatient clinic of our hospital for a second
Discussion
Amantadine, which was developed as a drug for influenza A virus in 1959, was later incidentally found to exhibit anti-parkinsonian effect in 1968 [4]. Since then, amantadine has been used in the management of PD worldwide. Notably, amantadine in addition to sulpiride [5] is pharmacologic therapy available for levodopa-induced dyskinesias, one of the motor complications in advanced stages of the disease [6]. Despite its frequent usage, there are only a few case reports of amantadine-associated
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