Therapeutic Briefs
Factors in Post-LP Headaches
Source: Evans RW, et al. Assessment: Prevention of post lumbar puncture headaches. Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology 2000;55:909-914.
Does a smaller needle, the prone position, increased fluid intake, or other variable prior to or following diagnostic lumbar puncture decrease the incidence of post lumbar puncture headache (PLPHA)? A Medline search from 1966 forward, and bibliographic review of these articles to search for earlier ones, unearthed telling results. Women, prior headache history, younger age, and small body mass index (weight/height2) were positively associated with PLPHA, whereas higher gauge (smaller diameter) needle, needle insertion parallel to dural fibers (bevel up with patient on side), and replacing the stylet prior to needle removal were negatively associated with PLPHA. Noncutting needles, with a dull tip and oval opening (Whitacre or Sprotte), may or may not be of benefit. Volume of spinal fluid removed, recumbency (regardless of position), and hydration following spinal tap were of no benefit in preventing PLPHA. Future studies should address the role of noncutting needles and whether other factors may effect the incidence of PLPHA. —Michael Rubin
Riluzole for Neuropathy?
Source: Galer BS, et al. Lack of efficacy of riluzole in the treatment of peripheral neuropathic pain conditions. Neurology 2000;55:971-975.
Riluzole does little for amyotrophic lateral sclerosis. It appears to do even less for painful neuropathy. Two prospective, randomized, double-blind, placebo controlled, crossover trials compared riluzole 50 mg bid or 100 mg bid to placebo in 21 and 22 patients respectively, with chronic (> 3 months) painful neuropathy. Diagnoses included postherpetic neuralgia (n = 22), nondiabetic polyneuropathy (n = 19), and diabetic polyneuropathy (n = 2). Each treatment phase lasted two weeks, followed by a two-week washout period and crossover into the other arm. Exclusionary criteria included the following: a history of liver disease or alcoholism; use of antidepressant or anticonvulsant medication within seven days of entry into trial; psychiatric or seizure disorder requiring continued antidepressant or anticonvulsant medication; elevated liver function studies or depressed white blood cell count; pregnancy; lactation; or nonadherence to birth control. Primary outcome measures comprised change in pain scores at two week intervals. Secondary outcome measures included change in average daily pain scores using a visual analog scale, the Neuropathic Pain Scale, allodynia, hyperalgesia, and patient preference. Statistical analysis was performed by ANOVA measures and Wilcoxon’s Signed Ranks Test. Despite its ability to block sodium channels and depress glutamate transmission, properties which should alleviate neuropathic pain, riluzole failed to effect any significant improvement in any outcome measure in any group at any time. —Michael Rubin
Cough Syrup for Facial Neuralgia?
Source: Gilron I, et al. A randomized controlled trial of high dose dextromethophan in facial neuralgias. Neurology 2000; 55:964-971.
Nineteen patients with facial neuralgia enrolled in a six-week, double-blind, randomized, crossover trial comparing oral dextromethophan to active placebo (lorazepam, to mimic side effects for better blinding without producing analgesia), titrated to a maximum of 920 mg/d qid or 1.84 mg/d, respectively, in a qid regimen. Inclusion criteria included ages 18 to 89, unremitting pain for more than three months, normal hepato-renal function, and adequate contraception. Diagnoses included idiopathic trigeminal neuralgia (n = 3), anesthesia dolorosa following gasserian ganglion ablation (n = 5), and pain with possible trigeminal neuropathy (n = 11). Exclusionary criteria included treatment with selective serotonin reuptake inhibitors (SSRIs), TMJ disorders, multiple sclerosis, psychiatric disorders, substance abuse including alcoholism, hepatic, renal, or cardiac disease, pregnancy or lactation. Overall daily pain was the primary outcome measure and secondary outcome measures included continuous pain intensity, and intensity, frequency, and duration of paroxysmal pains. Student’s t-test and Mann-Whitney U test were used for statistical analysis.
Only three patients demonstrated an analgesic response to dextromethophan and this was reproduced in only one patient in four subsequent drug-placebo crossovers. Despite its ability to decrease pain in laboratory models of nerve injury and in diabetic and postherpetic neuralgia, presumably based on NMDA glutamate receptor antagonism, dextromethophan is of no significant benefit in facial neuralgia. —Michael Rubin
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