Electrophysiological study in 2 children with transient hypohidrosis induced by topiramate.

OBJECTIVE: Hypohidrosis, often associated with hyperthermia, has been reported, mostly in children, as a rare and reversible adverse effect of topiramate, an anticonvulsant drug with a broad spectrum of antiepileptic activity. The aim of our study is to detect a possible skin innervation involvement as the mechanism underlying hypohidrosis in children treated with topiramate. METHODS: A neurophysiological study has been performed on 2 children who have developed hypohidrosis under topiramate treatment. Electrophysiological data have been recorded during topiramate treatment and compared with a control group. Sympathetic skin responses have been recorded during topiramate assumption and after its discontinuation. RESULTS: In our 2 cases with hypohidrosis related to topiramate, electrophysiological study showed normal function of both beta and delta sensory fibers and absent sympathetic skin responses that recovered to normal after topiramate discontinuation. CONCLUSIONS: Our findings confirm that topiramate might induce a transitory specific carbonic anhydrase block at the level of sweat glands, without involvement of peripheral nervous system.

Intra-oral orthosis vs amitriptyline in chronic tension-type headache: a clinical and laser evoked potentials study.

BACKGROUND: In the present study, we examined clinical and laser-evoked potentials (LEP) features in two groups of chronic tension-type headache (CTTH) patients treated with two different approaches: intra-oral appliance of prosthesis, aiming to reduce muscular tenderness, and 10 mg daily amitriptyline. METHODS: Eighteen patients with diagnosed CTTH participated in this open label, controlled study. A baseline evaluation was performed for clinical features, Total Tenderness Score (TTS) and a topographic analysis of LEPs obtained manually and the pericranial points stimulation in all patients vs. healthy subjects. Thereafter, patients were randomly assigned to a two-month treatment by either amitriptyline or intra-oral appliance. RESULTS AND DISCUSSION: Both the intra-oral appliance and amitriptyline significantly reduced headache frequency. The TTS was significantly reduced in the group treated with the appliance. The amplitude of P2 response elicited by stimulation of pericranial zones showed a reduction after amitriptyline treatment.Both therapies were effective in reducing headache severity, the appliance with a prevalent action on the pericranial muscular tenderness, amitriptyline reducing the activity of the central cortical structures subtending pain elaboration CONCLUSION: The results of this study may suggest that in CTTH both the interventions at the peripheral and central levels improve the outcome of headache.

Efficacy of levetiracetam in Huntington disease.

OBJECTIVE: Levetiracetam (LEV) is a novel antiepileptic drug characterized by a wide spectrum of action; no pharmacologic interaction and poor adverse events are reported. In animal models, effects of LEV are observed in basal ganglia. The aim of this study was to evaluate the efficacy of LEV in reducing involuntary movements in subjects affected by Huntington disease (HD). METHODS: This was a single-center, short-term, open-label, controlled study. Patients had LEV as add-on therapy for 6 months. In the first visit patients were rated according to the Unified Huntington Disease Rating Scale. Every 2 months they were submitted to all these tests. LEV was added at the dose of 500 mg twice daily for the first 2 months and then the dosage was increased until 1000 mg twice daily for the next 4 more months. The authors enrolled 22 patients: 15 were assigned to the LEV group and 7 were enrolled as control subjects. RESULTS: No serious adverse events were experienced by the treated patients. After 6 months of treatment patients on LEV showed a significant reduction of involuntary movements, with a slight improvement of functional capacity compared with the control group. CONCLUSION: Results of this short-term, prospective, controlled study indicates that in HD patients, LEV is effective in reducing involuntary movements, thus improving the quality of life.

Lack of habituation of nociceptive evoked responses and pain sensitivity during migraine attack.

OBJECTIVE: The aim of the present study was to investigate the habituation of subjective pain sensation to CO(2) laser stimulus, in relation to the amplitude modifications of the cortical evoked responses (LEPs), during both the migraine attack and the not symptomatic phase. METHODS: Fourteen migraine patients were selected and compared with 10 healthy controls. Eight patients were evaluated during both the pain-free and the attack phases. Three following series of 20 averaged LEPs were recorded, stimulating the hands and the supraorbital zones: during the attack, two consecutive series of 20 averaged LEPs were carried out. The subjective sensation was requested for each laser stimulus, using a 0-10 points Verbal Rating Scale (VRS). RESULTS: In normal subjects the N2-P2 waves amplitude showed habituation across the three repetitions, which correlated with the habituation of the subjective rating of the stimulus. During the not symptomatic phase, patients showed a lack of habituation of the N2-P2 amplitude when the hand and the face was stimulated, with a pattern of increase of the pain rating across the three repetitions; in addition there was a lack of correlation between the LEPs amplitude and the subjective sensation. During the attack, the LEPs amplitude and the pain rating were increased when the face was stimulated, but they did not habituate across the two repetitions, likely the pain-free condition. The percent LEPs amplitude variation across the three repetitions correlated with the main indices of migraine severity, mainly when the supraorbital zone was stimulated. CONCLUSIONS: The abnormal cortical excitability in migraine could condition an anomalous behavior of nociceptive cortex during the interictal phase of migraine: it persists during the acute phase, and correlates with the frequency and duration of migraine. SIGNIFICANCE: The reduced habituation of the nociceptive cortex may concur with the onset and evolution of headache.