4-Aminopyridine restores neural integrator function in downbeat nystagmus

Downbeat nystagmus (DBN), the most common form of acquired fixation nystagmus is often caused by cerebellar lesions. The precise pathomechanism is not yet known, but may be due to a deficiency of inhibitory floccular purkinje cell (PC) output. The potassium-channel blocker 4-aminopyridine (4-AP) has been shown to increase the excitability of cerebellar PCs. To test whether 4-AP is suited as treatment option for DBN, the nystagmus of fifteen patients with DBN due to different etiologies were investigated with the search-coil technique before and 45 minutes after ingestion of 10mg 4-AP. 4-AP on average suppressed…