The use of F-wave and sural potential in the diagnosis of subclincal diabetic neuropathy in Saudi patients.

OBJECTIVE: To compare nerve conduction parameters in asymptomatic diabetic patients and with no clinical signs of neuropathy and in control subjects. METHODS: Forty-eight diabetic Saudi subjects (20 males, 28 females) and 48 age-and-sex-matched control subjects were studied. The mean age of patients +/- standard deviation was 45.6+/-11.7 years. The mean duration of diabetes from time of diagnosis was 10.8+/-3.1 years, and their mean fasting plasma glucose was 8.5+/-0.9 mmol/l. Nerve conduction studies were performed on the right lower limb. RESULTS: In diabetic patients the tibial and peroneal nerve conduction velocity values were 48.6+/-4.7 and 46.3+/-5.2 m/s. They were not significantly different from controls (p>0.01). The tibial and peroneal distal motor latency values were 5.1+/-0.6 and 4.7+/-0.9 ms, and not significantly different from controls (p>0.01). The sural nerve distal sensory latency in patients was 3.2+/-0.7 ms and the sural sensory nerve action potential amplitude was 4.9+/-2.5 uV. These values were significantly different from controls (p<0.01). The tibial and peroneal minimal F-wave latency values in patients were 32.5+/-1.9 ms/m and 32.9+/-1.6 ms/m, and were significantly different from controls (p<0.001). The F-wave average duration values in patients were 11.8+/-1.5 ms for the tibial nerve and 9.0+/-1.4 ms for the peroneal nerve. These were significantly different from control (p<0.001). CONCLUSION: The peroneal and tibial minimal F-latency and average F-duration provide the most sensitive nerve conduction; indicators for the diagnosis of subclinical neuropathy in diabetes.

The diaphragmatic compound muscle action potentials (DCMAPs) at different lung volumes--a prospective electrophysiological study of the respiratory system.

Phrenic nerve conduction study and measurements of static lung volumes such as functional residual capacity (FRC), total lung capacity (TLC) and residual volumes (RV) using body plethysmography were carried out in 31 normal healthy male subjects (31 +/- 8 years). The objective was to correlate changes in latency, amplitude, duration and area of diaphragmatic compound muscle action potential (DCMAPs) with lung volumes and changes in them with changes in postures. The mean phrenic nerve latency did not show any significant change with lung volumes or postures, but the latency and height of the subject had a significant correlationship (r = 0.68). The peak to peak amplitude of DCMAP showed a significant relationship with the quantitative lung volumes (r = 0.65). The amplitude was significantly higher and duration reduced (p < 0.001) at TLC as compared with those at measured FRC and RV in both sitting and supine postures. The area under the curve did not change significantly. Similarly, amplitudes and latency did not show any significant relation with other anthropometric parameters. The study evaluates a new quantitative relationship between DCMAPs amplitude and lung volumes. This may be carefully used along with other clinical parameters in critically ill patients for an early weaning from ventilator. Posture exerts minimal influence on DCMAPs amplitude; since DCMAPs amplitudes depends on the position of the diaphragm which in turn depends on dipolic potential, its electromagnetic fields and its moving angle subtends at the recording electrode, one can confidently use it to predict lung volume in respiratory failure due to neuromuscular diseases where subjective lung function assessment is impossible. However, a further study is in process in the critical care unit to confirm its utility.

Motor terminal latency index in carpal tunnel syndrome.

We determined the motor terminal latency index (MTLI) of the median nerve across the carpal tunnel in 41 upper extremities of 31 patients with carpal tunnel syndrome. Changes in motor nerve conduction velocity (MNCV), motor terminal latency (MTL), sensory action potential and the amplitude of the compound muscle action potential recorded from the abductor pollicis brevis muscle were all suggestive of proximal and distal segment involvement of the nerve across the carpal tunnel. There was no correlation between forearm MNCV and MTL (r = 0.40), although MTLI was correlated with MTL (r = 0.67) but not with MNCV, indicating a disproportionate conduction across the carpal tunnel.

Terminal Latency Index: A distinctive diagnostic criterion for carpal tunnel syndrome.

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Motor terminal latency index in carpal tunnel syndrome

We determined the motor terminal latency index [MTLI] of the median nerve across the carpal tunnel in 41 upper extremities of 31 patients with carpal tunnel syndrome. Changes in motor nerve conduction velocity [MNCV], motor terminal latency [MTL], sensory action potential and the amplitude of the compound muscle action potential recorded from the abductor pollicis brevis muscle were all suggestive of proximal and distal segment involvement of the nerve across the carpal tunnel. There was no correlation between forearm MNCV and MTL [r = 0.40], although MTLI was correlated with MTL [r = 0.67] but not with MNCV, indicating a disproportionate conduction across the carpal tunnel

Centro-temporal benign epilepsy in Saudi children.

A review of 36 interictal EEGs compatible with the diagnosis of benign childhood epilepsy with centro-temporal spikes (BECTS) was made in this study. These children constituted 31% of the children with focal epileptic EEG activity observed in the same period. The dipolic spikes occurred either as a single focus (78%) or as two independent foci with a greater preponderance to the right (22%). The onset of seizures before the age of 5 years (Group I) is 53% and between 6 and 10 years (Group II) is 47%. Clinical evaluation showed that 60% of the patients in Group I and 75% in Group II had lateralized seizures, although all of them were initially diagnosed as nocturnal generalized tonic-clonic seizures. A follow-up study showed 31% complete recovery, 47% seizure-free under medications, 8% occasional seizures, 8% frequent seizures, and the rest 6% had a single seizure without medication. It is therefore concluded that the syndrome is common in Saudi Arabia and is usually unrecognized by the general physicians. The follow-up of our patients so far confirms the excellent prognosis.

Nocturnal epilepsies in adults.

We evaluated the clinical characteristics and the electroencephalographic (EEG) findings by long video-EEG monitoring in 64 successive patients with definite nocturnal seizures. Mental state, neurological examination, neuroimaging and EEG background were normal in all patients. Classification of epilepsies was possible in 42 out of 64 (66%) patients according to the revised Classification of Epilepsies and Epileptic Syndromes by the Commission on Classification and Terminology of International League Against Epilepsy (1989). Out of those 42 patients, 33 (79%) had partial epilepsies, while 9 (21%) had generalized epilepsies. Response to antiepileptic drugs was excellent and only 4 (6%) patients had one seizure attack per year, two of them were on two antiepileptic drugs while the others were free of seizure on a single drug during the 2 years of follow-up. It seems that nocturnal seizures in adults form a new distinctive partial epileptic syndrome of a benign entity.

Diagnostic role of brain-stem auditory evoked potentials in neurobrucellosis.

Evoked potential audiometry and brain-stem auditory evoked potentials were evaluated in 15 patients with systemic brucellosis in whom brucella meningitis was suspected clinically. In 8 patients cerebrospinal fluid (CSF) was abnormal with high brucella titre, and evoked potentials were abnormal in all of them. In 7 patients the CSF was normal and evoked potentials were also normal. Brain-stem auditory evoked potential abnormalities were categorised into 4 types: (1) abnormal wave I, (2) abnormal wave V, both irreversible, (3) prolonged I-III interpeak latencies, and (4) prolonged I-V interpeak latencies, both reversible. These findings are of important diagnostic value and correlate well with the clinical features, aetiopathogenesis and final outcome.

Measurement of reversibility of airways obstruction: which parameters to use?

Maximum expiratory flow-volume (MEFV) curves recorded before and after salbutamol inhalation on 100 patients with various lung diseases were studied. Improvement was found to occur more frequently in MEF50, FEF25-75, FVC and MEF25, than in FEV1, FEV1/FVC%, or MTT. If improvement in only one of the first four parameters was taken as a measure of reversibility of airways obstruction, many cases showing improvement in the others were missed. Improvement in any of the last three parameters was rarely missed if improvement in any of the first four was present. It was concluded that there is no single best measurement for assessment of bronchodilator response. FVC, FEF25-75, MEF50 and MEF25 should all be measured. A flow-volume record of forced expiration from which all these measurements can be derived would therefore be preferable for this purpose to the time-volume spirometer record from which only FVC and FEF25-75 can be determined.