Predicting acute denervation in carpal tunnel syndrome.

OBJECTIVE: To determine which nerve conduction parameters can predict the presence of acute denervation in carpal tunnel syndrome. SETTING: The electrodiagnostic laboratories of a hospital and a county hospital district. DESIGN: A retrospective review. PATIENTS: A total of 1,590 consecutive cases from January 1992 to June 1996, diagnosed as having median neuropathy at the wrist. MAIN OUTCOME MEASURES: Evidence of acute denervation on needle electromyography of the abductor pollicis brevis and its relationship to patient age, gender, and parameters obtained from nerve conduction studies, including median sensory latency and amplitude, and median motor latency and amplitude. RESULTS: Logistic regression analysis identified gender, median motor latency, and median motor amplitude (all p < or = .008) as contributing to the prediction of denervation. Needle examination of the cases with a median motor amplitude <7 mV detected 95.3% (141/148) of all cases with denervation and could have spared 52% (708/1,362) of the population from a needle examination of the abductor pollicis brevis. CONCLUSION: The median motor amplitude can predict the presence of acute denervation in the thenar muscles in median neuropathy at the wrist and possibly eliminate a painful needle examination of the median-innervated thenar muscles in over 50% of the cases.

Effect of mexiletine on spinal cord injury dysesthetic pain.

Severe pain occurs in 5-30% of the spinal cord-injured (SCI) population and is difficult to treat. Subarachnoid lidocaine has been used in selected patients with some success. Mexiletine, an analog of lidocaine that acts at Na+/K+ channels in the peripheral nerve, has been found effective in persons with diabetic dysesthetic neuropathy. The effect of mexiletine in the treatment of spinal cord dysesthetic pain was examined in this study. Fifteen patients were enrolled, and 11 patients completed the prospective, randomized, placebo-controlled, double-blind, crossover design trial. Inclusion/exclusion criteria were carefully defined. A 1-wk washout period was followed by a 4-wk drug trial of either mexiletine (450 mg/day) or placebo. This was repeated for the second medication in the second arm of the study. Patients were followed weekly with McGill and visual analog pain scales. Baseline, midpoint, and endpoint Barthel function scores were recorded. The Wilcoxon's signed-rank test and paired t test were used for statistical analysis. Results showed no significant effect of mexiletine on SCI dysesthetic pain scales or Barthel index. In conclusion, in this trial, mexiletine did not appear to decrease spinal cord injury-related dysesthetic pain.

Pleural effusions due to Cryptococcus neoformans: a review of the literature and report of two cases with cryptococcal antigen determinations.

Pleural effusions due to Cryptococcus neoformans occurred in 2 patients, 1 with localized pulmonary infection and 1 with disseminated cryptococcosis. Cryptococcal antigen was present in the pleural fluid from both patients and it was present also in the serum and cerebrospinal fluid of the patient with disseminated infection. The cryptococcal antigen test is a sensitive and specific indicator of cryptococcoal infection, and it was not positive in pleural fluid samples from a variety of other conditions including bacterial and mycobacterial infections and primary or metastatic malignancies. Twenty-eight additional cases of cryptococcal pleural effusions have been reported in the English literature, equally divided between patients with infection localized to the thorax and those with disseminated disease. Cryptococcal infection must be considered in the differential diagnosis of patiients with pleural effusion, especially patients with serious underlying diseases treated with corticosteroids. The cryptococcal antigen test appears to be a useful adjunct in diagnosis, and serial determinations may be helpful in assessing response to treatment.

Do condom catheter collecting systems cause urinary tract infection?

A study was undertaken to determine whether use of a condom catheter collection system (CCCS) is associated with urinary tract infection (UTI). No UTI developed in 79 episodes of CCCS use in patients who were cooperative or because of paralysis were unable to manipulate the collecting system (mean time per patient, 21.2 days; total number of patient days, 1,677). By contrast, in 15 patients who were identified prospectively as being uncooperative and who repeatedly manipulated the CCS, UTI developed in eight (53.3%) within a mean of 9.6 days. Urethral catheterization in cooperative patients during CCCS use was followed by development of UTI. Repeated interference with the proper use of CCCS and urethral catheterization during CCCS use are associated with an increased risk of UTI.