Tetsuro Nikai

Intercostal nerve block with 5% tetracaine for chronic pain syndromes

Treating chronic pain syndromes is always challenging. We describe an effective use of an intercostal nerve block using 5% tetracaine in three patients with postherpetic intercostal neuralgia or postoperative intercostal neuralgia.

Intravenous Infusion of Remifentanil Induces Transient Withdrawal Hyperalgesia Depending on Administration Duration in Rats

BACKGROUND Recent studies suggest that remifentanil, similar to other μ-opioid agonists, may induce hyperalgesia. We performed animal experiments to determine whether IV remifentanil infusion, the mode of administration used in clinical practice, induces hyperalgesia and the conditions in which this phenomenon occurs. We also determined whether remifentanil-induced hyperalgesia is related to extracellular signal-regulated protein kinase 1/2 (ERK1/2) phosphorylation. METHODS Remifentanil was administered through a catheter in the tail vein of male Sprague-Dawley rats for 10 minutes (30 μg · kg(-1) · min(-1)), 30 minutes (0.1, 1, and 10 μg · kg(-1) · min(-1)), or 120 minutes (0.1, 1, 3, and 10 μg · kg(-1) · min(-1)). The von Frey test and a tail-flick test were performed, followed by ERK1/2 immunohistochemistry. We examined whether intrathecal preadministration of the mitogen-activated protein kinase inhibitor U0126 suppresses hyperalgesia. RESULTS Remifentanil had a dose-dependent antinociceptive effect that rapidly diminished. Ten- or 30-minute remifentanil infusion did not induce hyperalgesia. However, tail-flick latency and mechanical pain threshold after infusion termination were significantly lower in the 120-minute remifentanil administration group than those in the control group, regardless of dose. Hyperalgesia duration was no longer than 60 minutes. Significantly more phospho-ERK1/2-immunoreactive neurons in the superficial spinal dorsal horn were observed in the remifentanil 120-minute groups with hyperalgesia than in the 30-minute remifentanil groups without hyperalgesia, although U0126 did not suppress hyperalgesia. CONCLUSIONS IV remifentanil induces transient withdrawal hyperalgesia soon after its termination. This hyperalgesia is strongly associated with the duration of exposure to remifentanil. Contrary to our hypothesis, ERK1/2 by itself was not the essential factor involved in the induction of the hyperalgesia.

Lumbar sympathetic block for pain relief in two patients with interstitial cystitis

Background and Objectives Interstitial cystitis (IC) is characterized clinically by lower abdominal pain, pain during urination, and increased frequency of urination. Treatment of the symptoms in IC remains challenging. We report effective treatment using lumbar sympathetic block for 2 patients with IC. Case Report A 63-year-old and 78-year-old woman were diagnosed with IC. Medical therapy with nonsteroidal anti-inflammatory drugs (NSAID), anticholinergics, and hydrodistention of the bladder failed to improve their symptoms. Subsequently, a continuous lumbar epidural block using 1% mepivacaine was used in these patients. A transient reduction of the symptoms in both patients was achieved. A lumbar sympathetic block with a neurolytic agent produced almost complete, and long-lasting relief of their symptoms. Conclusion Lumbar sympathetic block using a neurolytic agent produced long-lasting pain relief in 2 patients with IC.

Evaluation of peripheral nerve function using current perception threshold in the herpes zoster patients and the development of post-herpetic neuralgia

Abstract Background: We performed this study to evaluate peripheral nerve function in patients with herpes zoster (HZ) using current perception threshold (CPT) and to compare results between patients who developed post-herpetic neuralgia (PHN) and those who did not. Methods: With Institutional Review Board (IRB) approval and informed consent, 27 patients with HZ were enrolled in the study. At the first visit, all patients were examined clinically and neurophysiologically. CPTs were determined at stimulus frequencies of 2000, 250, and 5 Hz in the affected region and in the contralateral site. Patients were re-examined 6 months after the onset of their symptoms. Patients who still had pain were defined as PHN patients and the others as non-PHN patients. Results: CPT values in affected areas were significantly higher than those in unaffected areas. Thirteen patients were included in the PHN group, and 14 patients in the non-PHN group. Visual analogue scale (VAS) values at the first visit were significantly h...