Hassan I. Kotb

Longlasting antalgic effects of daily sessions of repetitive transcranial magnetic stimulation in central and peripheral neuropathic pain

Background and objective: A single session of repetitive transcranial magnetic stimulation (rTMS) over motor cortex had been reported to produce short term relief of some types of chronic pain. The present study investigated whether five consecutive days of rTMS would lead to longer lasting pain relief in unilateral chronic intractable neuropathic pain. Patients and methods: Forty eight patients with therapy resistant chronic unilateral pain syndromes (24 each with trigeminal neuralgia (TGN) and post-stroke pain syndrome (PSP)) participated. Fourteen from each group received 10 minutes real rTMS over the hand area of motor cortex (20 Hz, 10×10 s trains, intensity 80% of motor threshold) every day for five consecutive days. The remaining patients received sham stimulation. Pain was assessed using a visual analogue scale (VAS) and the Leeds assessment of neuropathic symptoms and signs (LANSS) scale, before, after the first, fourth, and fifth sessions, and two weeks after the last session. Results: No significant differences were found in basal pain ratings between patients receiving real- and sham-rTMS. However, a two factor ANOVA revealed a significant “± TMS” × “time” interaction indicating that real and sham rTMS had different effects on the VAS and LANSS scales. Post hoc testing showed that in both groups of patients, real-rTMS led to a greater improvement in scales than sham-rTMS, evident even two weeks after the end of the treatment. No patient experienced adverse effects. Conclusion: These results confirm that five daily sessions of rTMS over motor cortex can produce longlasting pain relief in patients with TGN or PSP.

Repetitive transcranial magnetic stimulation in neuropathic pain secondary to malignancy: A randomized clinical trial

Significant analgesic effects of repetitive transcranial magnetic stimulation (rTMS) have been found in several studies of patients with chronic pain of various origins, but never for malignancy. The objective of this study was to assess the efficacy of 10 sessions of rTMS over the primary motor cortex (M1) in patients suffering from malignant neuropathic pain.

Comparative evaluation of the effect of tricyclic antidepressants on inducible nitric oxide synthase expression in neuropathic pain model

The analgesic effect of acute i.p. administration of amitriptyline (norepinepherine and serotonin reuptake inhibitor), clomipramine (serotonin reuptake inhibitor) and desipramine (norepinepherine reuptake inhibitor) was studied in chronic constriction injury (CCI) model of sciatic nerve in rats and mRNA and protein expression of inducible nitric oxide synthase (iNOS) were also investigated. Acute treatment with amitriptyline and clomipramine produced antinociceptive effects after sciatic nerve injury and blockade of norepinephrine reuptake using desipramine did not demonstrate antinociceptive effects. The antinociceptive effect of amitriptyline, not clomipramine, was augmented by the selective iNOS inhibitor, aminoguanidine. Amitriptyline inhibited iNOS mRNA and protein expression in cerebellum and hippocampus. However, desipramine altered neither iNOS expression at mRNA level nor at post-transcriptional level. Based on our experimental findings, we conclude that the analgesic effect of the dual norepinepherine and serotonin reuptake inhibitor, amitriptyline, is partially due to inhibition of central iNOS.

Epidural Abscess after Spinal Anesthesia: A Favorable Outcome

A case of lumbar epidural abscess after spinal anesthesia with sciatica and sphincteric disturbance is presented. The case was investigated by myelography and diagnosed after exploration, resulting in dramatic improvement.

Effect of Transcranial Direct Current Stimulation of the Motor Cortex on Visceral Pain in Patients with Hepatocellular Carcinoma

Objective Hepatocellular carcinoma (HCC) is frequently associated with visceral pain. Transcranial direct current stimulation (tDCS) has been proven to reduce chronic pain; however, its effectiveness in malignant visceral pain is unknown. This study aimed to investigate the effects of tDCS in patients with visceral pain due to HCC. Design This is a randomized, sham-controlled, double-blind, prospective study. Forty patients with visceral pain due to HCC were enrolled and randomly assigned into two groups: a real and a sham group; tDCS was applied over the primary motor area (M1) for 10 consecutive days (2 mA, 30 minutes). Patients pain was evaluated by visual analog scale (VAS) and verbal descriptor scale (VDS) and for depression by Hamilton rating scale (HAM-D). Evaluation was done at prestimulation, after the first, fifth, and 10th sessions, and one month after the end of stimulation sessions. Results Real tDCS showed a reduction of VDS (P = 0.001, F = 4.01) and VAS (P = 0.001, F = 6.817) for HAM-D (P = 0.012, F = 5,077); the effect started from the fifth session and continued to one month after stimulation, while in the sham group the effect persisted for five days only. Percentage reduction in all scales in the real group after the 10th session was as follows: VDS P = 0.008, VAS P = 0.001, HAM-D = 0.001; for one month after the end of stimulation, it was as follows: VDS P = 0.001, VAS P = 0.037, HAM-D = 0.002. Conclusions tDCS proved to be an effective and clinically relevant therapeutic strategy for visceral pain due to HCC.

Reactive Astrogliosis in an Experimental Model of Fibromyalgia: Effect of Dexmedetomidine

To our knowledge, this is the first study which investigates the induction of neuroinflammation in rats using an acidic-saline model of fibromyalgia. It is well known that the hippocampus has a fundamental role in pain perception, and astrocytes play a crucial role in pain signaling. Our aim is to evaluate the ability of dexmedetomidine to attenuate the inflammatory responses induced in astrocytes. In a group of healthy rats, induction of chronic muscle pain by intramuscular injection of 100 µL of acidic saline on days 0 and 5 resulted in peripheral sensitization (measured using the von Frey test) and significant (p < 0.05) increases in IL-1β (160.2 ± 1.1 to 335.2 ± 1.8), IL-6 (100.1 ± 1.4 to 202.4 ± 1.1), and TNF-α (60.0 ± 0.7 to 115.5 ± 1). Light and electron microscopy revealed degenerative changes in the hippocampus and reactive astrogliosis. Immunohistochemistry showed increased expression of glial fibrillary acid protein and inducible nitric oxide synthase. Surprisingly, treatment with a single dose of an α2-adrenergic agonist, dexmedetomidine (5 µg/kg i.p.), attenuated these changes. This trial suggests that dexmedetomidine possibly directly acts on astrocytes, and a peripheral action is also suggested.