114 Letters to the Editor conduction studies revealed no abnormalities 5 Streib EW. Distal ulnar neuropathy as a cause of Patients were enrolled in an off label uncon- J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.56.1.114 on 1 January 1993. Downloaded from in the face, upper or lower extremities. finger tremor: a case report. Neurology trolled dose-ranging trial of buspirone using 1990;40: 153-4. Supramaximal stimulation of the tibial nerve anxiolytic dose guidelines. The starting dose elicited unusual late components in addition was 5 mg orally three times a day. The dose to F waves. Normal electrophysiological was increased every 3 days by 5 mg to a studies included blink reflex, median nerve Buspirone in progressive myoclonus maximum of 60 mg/d. Two of the patients somatosensory evoked potentials, brain stem epilepsy were videotaped performing a standardised auditory evoked potentials, visual evoked battery of clinical tests including Archime- potentials and EEG. des's spirals. Repetitive motor tests and The patient was given clonazepam, val- Progressive myoclonus epilepsy is a clinical myoclonus were scored using established proic acid and trihexyphenidyl without any syndrome with obligate features of myoclo- scales." In patients who were too neuro- relief of symptoms. Carbamazepine lessened nus and epilepsy and variable or inconstant logically impaired to comply with testing, a the palatopharyngolaryngeal movement and features of dementia and ataxia. The most simple Likert scale was used to evaluate also the muscle cramps in legs. common is Unverricht-Lundborg disease myoclonus: 0 = absent, + = mild, ++ = Ear clicks and palatopharyngolaryngeal (Baltic or Mediterranean myoclonus) but moderate, +++ = severe. involuntary movements seen in our patient other types include Lafora disease and mito- Myoclonus was unchanged in one patient can be clinically classified into "palatal myo- chondrial myopathy. and worsened in three (table). Patient 3 left clonus",' although the movements were not A serotonergic disturbance is suggested by the study at the starting dose reporting it exactly rhythmic and recurred at a slower rate reduced CSF5- HIAA in Baltic myoclonus made her more unsteady, and therefore she than the usual palatal myoclonus. Needle and the antimyoclonic effect of L- trypto- could not be tested. Patient 1, the only EMG showed myokymic discharges in the phan plus a monoamine oxidase inhibitor or employed patient, could not go to work at 60 palatal and mylohyoideus muscles in syn- 5-hydroxy-L-tryptophan in some patients.' mg/day. On the Myoclonus Evaluation Scale, chrony with the movement. These EMG The problem is that these observations do patient 1 went from 20% abnormality at findings differed from those reported in not point to a specific locus of abnormality in baseline to 33-44% on buspirone; patient 2 symptomatic "palatal myoclonus" showing the 5-HT system. from 43-56% to 47-53%, respectively. There rhythmic discharges at a faster rate,2 Serotonin (5-HT) receptor pharmacology were also no large differences on 10 timed although the previous EMG studies on "pala- has advanced rapidly, identifying multiple motor tasks. Patient 4 was too impaired to tal myoclonus" did not disclose firing pat- 5-HT receptors types. Only a few have been comply with formal testing, but his action- terns of each jerk in detail. Myokymic studied in experimental myoclonus. In rats, and sensory-evoked myoclonus appeared to discharges and muscle cramps in the legs the full 5-HT receptor agonist 8-OH- increase while spontaneous myoclonus was relieved by carbamazepine in the present case DPAT induces myoclonus but partial unchanged. may indicate that they arise from neu- 5-HT,A agonists such as buspirone do not. In all cases, the worsening of myoclonus romuscular hyperexcitability rather than a This pilot study was intended as a prelimi- was transient once the drug was stopped, and central oscillator. nary step in evaluation of the possible role of patients reported returning to their baseline Ephaptic transmission resulting from 5-HT,A receptor abnormalities in progressive level of function. demyelination can cause focal myokymia,3 myoclonus epilepsy. The 5-HT,A receptor is None ofthe patients experienced increased but in our patient there was no evidence of key to the 5-HT containing raphe neurons on seizures compared with their baseline, even organic lesions in the posterior fossa, nor which it is located, because its stimulation those with exacerbation of myoclonus. A other diseases suggesting diffuse injury or decreases cell firing. The activity of these brief head-shaking seizure occurred in hyperirritability of the peripheral nerves, for neurons may be especially important in patient 1 at 45 mg/d buspirone, a generalised example, in association with toxins, brainstem-mediated myoclonus, but the convulsion in patient 2 at 30 mg/d and in thyrotoxicosis, Guillain-Barre syndrome or raphe nuclei also project widely to forebrain patient 4 at 20 mg/d. No new dyskinesias polyneuropathy.' Facial myokymia, though and spinal cord. Buspirone (Buspar) is the were evoked. commonly seen in patients with pontine first clinically used 5-HT A agonist of its The incidence of irritability and sedation glioma, multiple sclerosis or Guillain-Barre class, widely prescribed as an anxiolytic.2 in our patients was higher than the 2% and syndrome, rarely involves the muscles inner- Since anxiety increases myoclonus in our 10% of 477 cases in the Physician's Desk vated by lower cranial nerves.' patient population, we also hypothesised that Reference, respectively. There may have been Myokymic discharges, also called grouped they may benefit from an anxiolytic. Much less dizziness (12% in PDR). fasciculations, usually cause vermicular evidence suggests buspirone exerts its clinical This uncontrolled observational study in movements,3 but involvement of the dorsal effect by stimulating pre-synaptic 5- HT,A a small number of patients suggests that interosseous muscles may cause tremor-like receptors. buspirone does not help and may exacerbate http://jnnp.bmj.com/ or flickering movements of the fingers." Two male and two female patients, aged myoclonus in progressive myoclonus epi- Myokymic discharges in the palatal muscles 15-22 years, with progressive myoclonus lepsy. Worsening of myoclonus was not could therefore cause movements resembling epilepsy who had failed conventional therapy explained by decreased anticonvulsant levels, "palatal myoclonus" or "tremor". Needle were identified. Standard diagnostic tests had and there are no experimental data to sup- EMG is important to differentiate palato- been performed including muscle enzyme port an interaction between buspirone and pharyngolaryngeal myokymia from the histochemistry. All were taking one or more anticonvulsants. Although a fluctuating base- essential "palatal myoclonus",' which has a anticonvulsants (valproic acid, clonazepam, line of patients with progressive myoclonus slower rate of movement than symptomatic lorazepam, or phenobarbital) for control of epilepsy could give the false impression of on September 25, 2021 by guest. Protected copyright. "palatal myoclonus". seizures, but none of the drug doses were drug-induced exacerbation, the patients JUNKO ITO the Each had improved when buspirone was discontin- JUN KIMURA changed during study. patient Department of Neurology prominent action myoclonus, some sponta- ued. HIROSHI SHIBASAKI neous myoclonus, and little or no cerebellar The data should be viewed as positive Department of Pathophysiology ataxia. None of the patients were seizure-free findings for several reasons. Any response to Kyoto University School ofMedicine, Sakyoku, Kyoto, for more than a few months before the start buspirone suggests that the 5- somato- _Japan. HTIA of the study. All had therapeutic anticon- dendritic autoreceptors are intact, and by Correspondence to: Dr Ito, Department of Neurol- vulsant levels before and during the study. inference, that 5-HT-containing raphe neu- ogy, Kyoto University Hospital, 54 Kawaracho Shogoin, Sakyo-ku, Kyoto 606-1, Japan. Table on and seizures 1 Deuschl G, Mischke G, Schenck E, Schulte- Effects of buspirone myoclonus Montig J, Liicking CH. Symptomatic and Days Threshold Max. Best Effect of myoclonus essential rhythmic palatal myoclonus. Brain on dose dose dosel Side Seizure 1990;113: 1645-72. Patient 2 Tahmoush AJ, Brooks JE, Keltner JL. Palatal Diagnosis drug mglday mglday day Subjective Obective effects frequency myoclonus associated with abnormal ocular 1 Baltic 60 15 60 35 worse No change Sedation 1 and extremity movements. A polygraphic Irritability study. Arch Neurol 1972;27:431-40. Mood swings 3 Gutmann L. AAEN minimonograph 37:facial 2 Baltic 18 25 30 20 worse worse Sedation 1 and limb myokymia. Muscle Nerve 1991;14: Lightheadedness 1043-9. 3 Baltic 3 15 15 - worse worse - 0 4 Kaeser HE, Skorpil V. Myokymia involving the 4 Lafora 13 5 20 - worse worse Sedation 1 muscles innervated by the Vth, VIth, VIIth, Irritability IXth, Xth, Xlth and XIIth cranial nerves with brain stem tumor. Eur Neurol 1976;14: 408-12. Best dose/day may indicate merely least side effects. Letters to the Editor 115 rons are also present. It also implies that the droxy-2-(Di-q-propylamino) tetralin in differ- matter' and would explain the findings in our J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.56.1.114 on 1 January 1993. Downloaded from ent rodent models of epilepsy Neurosci Letts 5-HT terminal is functional enough to