A randomized, placebo-controlled trial of repetitive spinal magnetic stimulation in lumbosacral spondylotic pain.

OBJECTIVE: Lumbar spondylosis is a degenerative disorder of the spine, whereby pain is a prominent feature that poses therapeutic challenges even after surgical intervention. There are no randomized, placebo-controlled studies utilizing repetitive spinal magnetic stimulation (SMS) in pain associated with lumbar spondylosis. In this study, we utilize SMS technique for patients with this condition in a pilot clinical trial. METHODS: We randomized 20 patients into SMS treatment or placebo arms. All patients must have clinical and radiological evidence of lumbar spondylosis. Patients should present with pain in the lumbar region, localized or radiating down the lower limbs in a radicular distribution. SMS was delivered with a Medtronic R30 repetitive magnetic stimulator (Medtronic Corporation, Skovlunde, Denmark) connected to a C-B60 figure of eight coil capable of delivering a maximum output of 2 Tesla per pulse. The coil measured 90 mm in each wing and was centered over the surface landmark corresponding to the cauda equina region. The coil was placed flat over the back with the handle pointing cranially. Each patient on active treatment received 200 trains of five pulses delivered at 10 Hz, at an interval of 5 seconds between each train. "Sham" SMS was delivered with the coil angled vertically and one of the wing edges in contact with the stimulation point. RESULTS: All patients tolerated the procedure well and no side effects of SMS were reported. In the treatment arm, SMS had resulted in significant pain reduction immediately and at Day 4 after treatment (P < 0.05). In the placebo arm, however, no significant pain reduction was seen immediately and at Day 4 after SMS. SMS in the treatment arm had resulted in mean pain reduction of 62.3% postprocedure and 17.4% at Day 4. The placebo arm only achieved pain reduction of 6.1% postprocedure and 4.5% at Day 4. DISCUSSION: This is the first study to show that a single session of SMS resulted in significant improvement of pain associated with lumbar spondylosis in a randomized, double-blind, placebo-controlled setting. The novel findings support the potential of this technique for future studies pertaining to neuropathic pain.

Continuous infiltration of local anaesthetic following total knee arthroplasty.

PURPOSE: To determine whether continuous infiltration of local anaesthetic can reduce the pain score and morphine use over 48 hours after total knee arthroplasty (TKA). METHODS: 11 men and 43 women aged 50 to 82 years who underwent unilateral TKA for osteoarthritis were recruited. They were randomised into 3 groups. In group 1, 17 patients who acted as controls received patient-controlled analgesia (PCA) with intravenous morphine for 48 hours. In group 2, 16 patients received continuous infiltration of bupivacaine to the subcutaneous tissue and intra-articular space for 48 hours, in addition to PCA. In group 3, 21 patients received an intra-articular injection of local anaesthetic, followed by continuous infiltration of bupivacaine to the subcutaneous tissue and intraarticular space for 48 hours, in addition to PCA. For each patient, a visual analogue score (VAS) for pain was recorded postoperatively at 2, 4, 6, 12, 24, 36, and 48 hours. The total amount of morphine used was recorded at 24 and 48 hours. RESULTS: Over 48 hours, the VAS for pain and morphine use was significantly higher in controls than patients in groups 2 and 3. CONCLUSION: Continuous infiltration of local anaesthetic into the intra-articular space and subcutaneous tissues, in addition to PCA with intravenous morphine, provides significantly more pain relief and reduces morphine use.

Association between caffeine intake and risk of Parkinson's disease among fast and slow metabolizers.

INTRODUCTION: Cytochrome P450 1A2 (CYP 1A2) is responsible for more than 90% of caffeine clearance. A polymorphic variant of CYP1A2 (-163C>A) (rs762551) is associated with high CYP1A2 inducibility. Both caffeine and its main metabolite, paraxanthine, may be neuroprotective. The association between caffeine intake and risk of Parkinson's disease (PD) in fast and slow caffeine metabolizers has not been compared. OBJECTIVE: In a case-control study, we analyzed the relationship between caffeine intake and risk of PD in both fast and slow caffeine metabolizers. METHODS: All the study participants were recruited prospectively, and interviewed for information on the amount and duration of caffeine intake. Genotyping of the CYP1A2 variant was carried out using the allelic discrimination method. RESULTS: Out of 1000 participants who were initially screened, 886 consisting of 418 PD and 468 race, sex and age matched controls were included. No evidence existed to suggest any association between CYP1A2 and the onset of PD (P=0.08). A significant association was seen between caffeine intake and the onset of PD (P=2.01x10(-5)), with the odds ratio for moderate and high drinkers at 0.71 [95% confidence interval (CI): 0.50-1.00] and 0.47 (95% CI: 0.34-0.65), respectively against the low drinkers. Multivariate analysis revealed no evidence of any interaction effects of caffeine with CYP1A2 (P=0.956). CONCLUSION: The association between caffeine intake and risk of PD was similarly observed in both fast and slow caffeine metabolizers, supporting experimental evidence in animal models that both caffeine and its major metabolite, paraxanthine, are neuroprotective.

Impaired motor imagery in patients with essential tremor: a case control study.

Motor imagery (MI), which refers to the process of mental representation of movements, has not been studied in patients with essential tremor (ET). We investigated the presence of impaired MI in ET patients compared with healthy controls. A group of drug-naive and nondemented ET patients and age-matched controls were studied using transcranial magnetic stimulation, while they were specifically instructed to try and imagine themselves performing two motor tasks. The various clinical and electrophysiological variables were evaluated and compared. Repeated measures ANOVA demonstrated a significant difference between ET patients and controls with respect to mean motor-evoked potential (MEP) amplitudes (F(1,38) = 31.92, P < 0.005) during MI. The process of MI effectively facilitated MEP amplitude in controls but not in ET patients, regardless of side of stimulation or motor tasks. We provide evidence to demonstrate impairment of MI in a group of ET patients compared with healthy controls. The basis for this novel finding is unclear, and further studies are warranted to determine whether it is related to cerebellar or motor cortical dysfunction.

Functional COMT variant predicts response to high dose pyridoxine in Parkinson's disease.

Pyridoxal-5-phosphate, the biological active form of pyridoxine, is a cofactor for dopa-decarboxylase (DDC) enzyme. Pyridoxine may augment the conversion of levodopa to dopamine in the periphery and therefore decrease availability of levodopa to the brain. However, this effect can be negated in the presence of a DDC inhibitor, which potentiates plasma levodopa level. A single nucleotide polymorphism at the nucleotide 1947 in the catechol-O-methyltransferase (COMT) gene encodes the high (COMT(H)) and low activity (COMT(L)) forms of the enzyme. In this study, we examined the effect of the COMT(L) allele on the clinical response to pyridoxine in Parkinson's disease (PD) patients. PD patients who were on stable and optimized dose of levodopa were included in this study. Their mean motor and activities of living score improved after high dose pyridoxine (P = 0.09, P = 0.04), and worsened after a washout period (P = 0.005, P = 0.001). Using a multivariate model, the presence of the COMT(L) allele predicted response to pyridoxine, with the best outcome observed in COMT(L/L) homozygotes. Our observational study suggests that the status the functional COMT(L) variant may be potentially useful to select PD patients for high dose pyridoxine therapy.