Current perception threshold screening for carpal tunnel syndrome.

Screening for the onset of carpal tunnel syndrome (CTS), which is associated with excess ergonomic stresses of the wrist and hand, is a major concern in occupational medicine. CTS questionnaires, physical examinations, and quantitative sensory function determination through neuroselective current perception threshold (CPT) measurements were obtained from the median digital nerves of 16 assembly line workers who were symptomatic with hand pain. Median nerve evaluations by CPT detected sensory abnormalities in 75% of the workers, and abnormalities in 50% of the workers were detected by clinical evaluations (p less than .05, df = 22). CPT abnormalities were characterized as "hypoesthetic" in 25% and hyperesthesic in 42% of the workers. The noninvasive, nonaversive CPT technique provided sensitive and easily obtained quantitative measures. Regular use of this procedure in the occupational setting may assist in preventing the development of advanced CTS for it provides early detection of median nerve abnormalities.

Sensory perception in uremic patients.

Peripheral (PNS) and central (CNS) sensory nervous system function was quantitatively assessed using neuroselective transcutaneous electrical nerve stimulation (TENS) in a population of 19 chronic hemodialysis patients (ages 17-77, median 47 years; duration 1-14, median 3 years). Cutaneous current perception threshold (CPT) provided an index of PNS integrity, and a new technique involving cranial TENS to characterize cephalic evoked noncutaneous sensations (CENS) was used to assess CNS sensory function. Patients showed both CPT (32%) and CENS (89%) abnormalities as compared with previously tested healthy subjects. No significant correlation was observed between age, duration of dialysis, PNS, and CNS abnormalities. The CPT examination provides a sensitive and easy to administer test of PNS sensory function for the purpose of assessing the adequacy of dialysis in chronic hemodialysis patients; the CENS examination also may prove useful in this regard.

Current perception threshold. Reproducibility and comparison with nerve conduction in evaluation of carpal tunnel syndrome.

Neuro-selective current perception threshold (CPT) values quantify peripheral nerve (n) integrity and provide an index of adequate hemodialysis (HD). Evaluation of polyneuropathy (PN) by CPT correlates with nerve conduction testing (NCT). CPT is convenient, painless, and may be performed during HD. Early detection of carpal tunnel syndrome (CTS), a complication of uremia, permits curative intervention. Utility of CPT and NCT measurements in detecting CTS in 29 stable HD patients were evaluated. Reproducibility of seven CPT determinations over 4 weeks was determined in each of 9 HD patients. The coefficient of variation for repeated 2000 Hz CPT measures was 6%. PN was detected by CPT in 92% of the patients and by NCT in 79% (r = 0.79, p less than 0.001). In 38% of the hands there was a CPT impairment in both the median and ulnar nerves (n), of which 25% were symptomatic for CTS. CPTs consistent with CTS (sufficiently greater impairment of the median vs ulnar n) were observed in 31% of the hands with combined median and ulnar n CPT abnormalities, and 11% were identified with CTS by NCT. The unique ability of the CPT exam to quantify hyperesthesia may account for its superior CTS detection sensitivity. These findings demonstrate that repeated CPT determinations are consistent and are diagnostic for CTS.

Neuropathy of uremia: evaluation by nerve conduction velocity versus neurospecific current perception threshold.

Normal peripheral nerve conduction is a marker of adequate dialytic therapy in the ESRD population. Decreasing nerve function detected by periodic testing indicates insufficient dialysis. The standard test for the quantitative evaluation of nerve integrity is the nerve conduction test (NCT). A study of 34 dialysis patients proves that the measurement of current perception threshold (CPT) is equally effective to NCT in defining peripheral nerve function (r = 0.81; p less than 0.001). The superiority of the CPT examination is discussed.

Current perception: preferred test for evaluation of peripheral nerve integrity.

While other parameters of dialysis may reflect acute events or lack specificity, assessment of peripheral nerve function remains a dependable indicator of the adequacy of high flux and rapid hemodialysis (HD). The nerve conduction test (NCT) is an accurate neurometric technique that is hampered by low patient compliance. This report examines the current perception threshold (CPT) test as a reliable alternative neurometric procedure to the NCT. The reliability of the CPT test was established in a one year longitudinal evaluation of 23 HD patients. CPT and NCT tests were performed on the median and peroneal nerves, bilaterally, with correlations of r = 0.83 for the initial determination and r = 0.80 one year later (P less than 0.001). CPT was shown to be a superior technique to NCT, as it is quick (tested during HD) and painless.

Hearing impairment associated with chronic renal failure.

The auditory sensitivity of 67 patients with chronic end-stage renal failure was assessed. In order to determine the incidence of hearing loss and to describe the impairment and possible contributing factors, one group of 39 patients was assessed prior to treatment by hemodialysis. Twelve of these subjects were then followed for 1 year as they are treated by hemodialysis. The remaining 27 patients, not treated by hemodialysis, were also retested in one year. A second group of 28 patients who ad been receiving hemodialysis over periods of 1 1/2, 3, and 6 years was also evaluated. A high incidence of high-frequency impairment was obtained which could not be attributed to age, noise exposure, ototoxicity, or hereditary. An association between this high-frequency impairment and both the renal disease and its treatment was suggested. Clinically significant sensorineural hearing loss did not appear associated with non-genetic kidney disease.

Hepatitis B vaccine: immune responses in haemodialysis patients.

Antibody to hepatitis B surface antigen (anti-HBs) developed within six months in 80% of haemodialysis patients given either two or three 40 micrograms doses of hepatitis B vaccine. A total of 89% had anti-HBs after a booster dose given six months later. Anti-HBs titres were higher in patients who received three initial doses than in those who received only two doses, but the proportion of anti-HBs-positive patients was the same in the two groups. Male patients became anti-HBs positive less often than females and their antibody titres were lower.

Presence of creatine phosphokinase brain band in the serum of chronic renal disease patients.

The almost universal presence of the isoenzyme creatine phosphokinase brain band (CPK-BB) in the sera of patients with chronic renal insufficiency and serum creatinine above 4.5 mg/dl is noted. It is absent in patients with severe acute renal failure and in transplanted patients with normal renal function. The source of the enzyme may be nerve tissue and may represent neuronal cell damage in uremics over a period of time.