Patients with
locked-in syndrome, although fully conscious, have
quadriplegia,
mutism, and lower cranial nerve
paralysis. The preservation of vertical gaze and upper eyelid movements usually enables them to interact with the environment through an eye-coded communication. However,
locked-in syndrome may be complicated by the development of an
opsoclonus-myoclonus syndrome that may represent an additional impediment to communication. We evaluated whether off-label treatment with
gabapentin could help patients with
locked-in syndrome and
opsoclonus-myoclonus symptoms regain voluntary control of full eye movements. A mechanism responsible for
gabapentin-induced improvement has been also hypothesized. In this study, 4 patients presenting with
locked-in syndrome complicated by
opsoclonus-myoclonus syndrome were continuously treated with
gabapentin up to 1200 mg/d. The treatment resulted in a rapid and long-lasting resolution of
opsoclonus-myoclonus symptoms without adverse effects. After 2 weeks, patients showed voluntary attempts to communicate through eye blinking and thereafter regained voluntary control of full eye movements. This event enabled them to regain a communication channel with relatives and physicians and to start using eye-controlled
brain-computer interfaces. Because of its effectiveness in restoring eye movement control,
gabapentin opened a communicative porthole in the patients' lives. Since
opsoclonus may be related to disorders of the inhibitory control of saccadic burst neurons by pontine pause cells, we hypothesize that
gabapentin acts as a regulator of saccadic circuits.