Failure of ondansetron in treating cerebellar tremor in MS patients - an open-label pilot study

* Cerebellar tremor is a frequent and disabling symptom in multiple scleros is (MS) patients. Supportive pharmacological treatment with different drugs showed only minor effects in a few studies and in clinical practice. Encou raged by previous studies with ondansetron, a 5HT(3)-antagonist, we conduct ed a small open-label, prospective and controlled study with 14 MS patients suffering predominantly from cerebellar tremor of the upper extremities. P rincipal outcome measure to evaluate a functional improvement of the single intravenous administered ondansetron injection was the subject performance in the 9-hole-peg-test (9HPT) and 3 blind assessed upper extremity writing and copying tasks. We neither found significant improvement in the upper e xtremity tests nor in the subjective response of the patients. In conclusio n we could not confirm a beneficial effect of ondansetron on cerebellar tre mor of MS patients.