Analgesic effects of flecainide on post herpetic neuralgia

Analgesic effects of flecainide on post herpetic neuralgia

Masahiko Ichimata, Haruyoshi Ikebe, Hitoshi Yamamoto, Sigenori Yoshitake,Hideo Iwasaka and Takayuki Noguchi Dept. of Anesthesiology, Oita Medical University, Oita, Japan

Aim of investigation: Sodium-channel blockers have been reported to improve clinical neuropathic pain. However, oral administration of a sodium-channel blocker such as mexiletine often does not reduce neuropathic pain, despite the efficacy of intravenous lidocaine administration. The class Ic antiarrythmic agent flecainide is a commercially available potent sodium-channel blockers. The purpose of this study was to evaluate the analgesic effects of flecainide on neuropathic pain in patients with post herpetic neuralgia.

Methods: Twenty patients with post herpetic neuralgia were enrolled in this study protocol. Firstly, according to the initial response to 2mg/kg of intravenous tiecainide administration, all patients were judged as a responder or non-responder. Responders were required to have VAS decrease of over 50% or more compared to the control value. All responders were administered 100mg/day of the flecainide orally during one week. After assessing VAS scores, all responders were administered 200mg/day of the oral flecainide. Effects of this dose were evaluated after four weeks.
Results: Fourteen patients judged as responders. In the 14 responders. 100mg/day of the oral flecainide did not improve their neuropathic pain nor reduce VAS significantly. In all responders. 200mg/day of the oral flecainide administration during four weeks lessened their neuropathic pain and reduces VAS significantly from 35.0± 13.1mm to 15.0± 14.4mm (mean±SD).
Conclusion: The analgesic effect of 200mg/day of the oral flecainide can be judged by the effectiveness of intravenous administration of flecainide. These results suggest that flecainide is useful for the treatment of neuropathic pain in patients with post herpetic neuralgia.

Herpes zoster and motor involvement. A seldom evaluated complication. A two case report and some practical consideratons

Elena Catala, Marta Ferrandiz, Isabel Ilia, Luis Aliaga, JM Villar Landeira.
Pain Clinic and Neurology service. University hospital de la Santa Creu i Sant Pau. 08025 Barcelona, SPAIN

Introduction: Pain and sensory disturbances are the main complications of Herpes Zoster (HZ). In contrast the motor involved is considered very rare or even not considered by some of the primary care physicians (pep) leading to additional patient anxiety and suffer. We present two case of different HZ localitazion with pain and motor involvement.
Case 1.- An 80-year-old woman referred by her pep to our Pain Clinic due to a PHN. The patient was suffering from a lancinating and burning pain in her right thoracic region ( T₁₀- T₁₂). Physical examination showed an intense allodynia and hyperesthesia of this area and a distension on the right part of the abdomen in contrast with her left side. After two months of oral treatment with Gabapentin 1200 mg /day and Metamizol 1800 mg/day patient pain decreased dramatically but her right abdomen side continued distended causing severe patient anxiety. The electromyography (EMG) showed a denervation in paravertebral muscles D₁₀- L₄ months after HZ. Polyphasic motor units (reinervation) were found.
Case 2.- A 58-year-old woman who developed a right lumbar HZ infection after the chimiotherapy treatment for a cancer process. She complained of pain in her right leg describing it as a lancinating. Clinical examination was significant for sensory loss in the right anteromedial thigh , some atrophy of her right quadriceps muscle (2/5) and decrease in right patellar reflex. Her left lower limb was normal. The EMG showed a L₃-L₄-L₅ right axonal polyradiculopathy secondary to the HZ infection. After 2 months of treatment with Gabapentin 1600 mg/day and physiotherapy the patient was pain free and only a slight motor deficit remained.
Conclusion: The HZ virus is not only a unique form of sensory neuritis but motor function involvement suggests that it is also a widespread infection. It is important to be aware of this implication for the following reasons: 1.- To avoid other complementary tests to explore other pathologies. 2.- The prognosis is good and it is important to inform the patient. 3.- A rehabilitation program should be incorporated when a limb is affected.