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Biomedical subjects

A S Wee

Publications and source records attributed to A S Wee.

At least 19 recordsLinked to original sources
PubMed2005

Effect of keto-acidosis on seizure occurrence in diabetic patients.

It has been observed anecdotally that diabetics are usually non-ketotic at the time of their seizure presentation. In order to establish some validity on this observation, we reviewed the medical records of patients with diagnoses of diabetes and seizure. Study subjects were diabetics presenting with seizures. Control subjects were random sampling of all diabetics. In 51 diabetics presenting with seizures, 38 were nonketotic and 13 were ketotic. In the control group of 119 diabetics, 63 were non-ketotic and 56 were ketotic. There were no significant differences in the serum levels of glucose, sodium, potassium, chloride, and calcium between the seizure and control groups. Multiple regression analysis showed that non-ketotic patients were at risk for developing seizures with an odds ratio of 4.03 (p=0.001). Male sex and type 1 diabetes were also risk factors while age was not a risk factor. Keto-acidosis may play a role in preventing epileptic seizures from occurring in diabetic patients.

Case-Control Studies↗
PubMed2004

Pain perception to nerve conduction and needle electromyographic procedures.

Pain survey was administered to 77 patients undergoing nerve conduction (NC) and needle electromyographic (EMG) procedures. The patient was asked to rate the pain immediately after the electrodiagnostic study was completed. Statistical analyses were performed to determine if there were relationships between pain and any of the technologic and physiologic variables. The findings revealed no significant correlation between age and pain from the NC or needle EMG procedure. The body mass index (BMI) also showed no correlation to pain from the procedures. Also, there was no correlation between pain and the EMG needle gauge or length. Pain from needle EMG was correlated with NC pain, and EMG was perceived as more painful than the NC procedure. Multiple regression analysis showed that age, sex, and needle size were not significantly related to pain from the EMG examination. Again, the age, sex, and BMI showed no significant relationship to pain from the NC test. From this survey, the individual's age, sex, habitus, and size of the EMG needle (to some extent) do not seem to influence significantly the perception of pain during electrodiagnostic procedures.

Adult↗
PubMed2003

Carpal tunnel syndrome: comparison of the median sensory nerve conduction findings from the index and middle fingers.

The sensory nerve conduction study (NCS) is a sensitive means for demonstrating the localized median nerve dysfunction at the wrist in carpal tunnel syndrome (CTS). We reviewed the sensory NCS data of 102 patients (178 median nerves) with CTS and tried to determine if there were significant differences in the findings between the index and middle fingers. There was no statistically significant difference in the amplitudes of the compound sensory nerve action potentials (CSNAPs) recorded antidromically from the index and middle fingers during median nerve stimulation at the palm and wrist. Moreover, there was no statistically significant difference in the finger-to-palm and palm-to-wrist sensory nerve conduction velocities (CVs) between the index and middle fingers. The mean CSNAP amplitudes and mean sensory CVs were comparable in values from these two fingers and they showed a high and positive correlation. It appears that the sensory nerves to the index and middle fingers are compromised to a similar degree in CTS, and neither finger will reveal significantly more sensory conduction abnormalities than the other will.

Action Potentials↗
PubMed2003

The sural sensory nerve is usually spared in Guillain-Barre syndrome.

Sensory nerve conduction (NC) studies that were performed on patients with Guillain-Barre syndrome (GBS) were reviewed. These were compared with the sensory NC findings in patients with peripheral neuropathy of the axonal-loss type (axonopathies) and chronic inflammatory demyelinating polyneuropathy (CIDP). In GBS, the sural sensory nerve frequently showed normal NC findings compared to the median and ulnar sensory nerves. The reverse pattern was seen in axonopathies and CIDP, in which the sural nerve showed more abnormalities than the median and ulnar nerves. This pattern of sensory NC abnormalities may assist the examiner in differentiating GBS from other types of peripheral polyneuropathy.

Adult↗
PubMed2002

Surface compound action potentials recorded from different locations on the anterior tibial muscle.

Supramaximal CMAPs to peroneal nerve stimulation at the knee were recorded from 5 locations on the anterior tibial muscle in 24 patients (30 muscles). The active recording locations were: midpoint of the muscle belly, at 4 cm distal and proximal to it, and at 2 cm lateral and medial to it. Reference electrode was at the medial malleolus. CMAP duration, amplitude, and area were measured, and ratios of their corresponding minimum to maximum values were computed. Thirteen patients (15 muscles) had normal nerve conduction and needle EMG studies. Mean ratios of minimum to maximum values were duration = 0.89, amplitude = 0.67, and area = 0.75. Eleven patients (15 muscles) had abnormal studies, and the mean ratios of minimum to maximum values were duration = 0.87, amplitude = 0.66, and area = 0.71. CMAP duration, unlike amplitude and area, appears least likely to be influenced by the recording electrode location, and is a more stable and reproducible measure during nerve conduction studies. The maximum (or minimum) values in the CMAP duration, amplitude, and area frequently do not coincide to one electrode recording location. A majority of the CMAPs recorded from different muscle locations had an initial negative phase, suggesting that the endplate zones of the anterior tibial muscle are dispersed rather than concentrated in a small region.

Action Potentials↗
PubMed2002

Comparison of the antidromic sensory nerve action potentials obtained from all fingers on the same hand.

Supramaximal compound sensory nerve action potentials (CSNAPs) were recorded antidromically from five fingers of the same hand to electrical stimulation of the median, ulnar, and radial nerves in 17 normal subjects. The mean amplitudes of the median CSNAPs from the thumb, index, and middle fingers were similar in values. There was minimal radial sensory contribution to the thumb, with the mean radial CSNAP amplitude about one-fourth the size of the median CSNAPs. The mean median and ulnar CSNAP amplitudes from the ring finger were approximately half, and the mean ulnar CSNAP amplitude from the little finger was approximately 85%, of the median CSNAP amplitudes from the other fingers. The median, ulnar, and radial sensory nerve conduction velocities were close in values. There appears to be less variability in the population normative data when the size of the CSNAPs is expressed in terms of amplitude ratio rather than in absolute amplitude value.

Action Potentials↗
PubMed2002

Needle electromyography in carpal tunnel syndrome.

The role of needle electromyography (EMG) in the routine evaluation of carpal tunnel syndrome (CTS) is not clear. The aim of this study was to determine if needle EMG examination of the thenar muscles could provide useful information in addition to the nerve conduction (NC) studies. Electrophysiologic procedures performed on 84 patients (103 hands) consistent with CTS were reviewed. The median thenar motor NC data were matched with the needle EMG findings in the abductor pollicis brevis (APB) muscle. The severity of the needle EMG findings in the APB muscle correlated well with the severity of the motor NC data. As the thenar compound muscle action potential amplitude decreased and the degree of nerve conduction slowing and block across the wrist increased, there was a corresponding increase in the number of enlarged motor units and decrease in the recruitment pattern in the needle EMG findings. Needle EMG examination confined to the thenar muscles in CTS does not seem to provide any further information when the NC data had already established this diagnosis, and it should not be performed routinely.

Adult↗
PubMed2002

Relative incidence of needle EMG abnormalities in the anterior tibial and gastrocnemius muscles.

Foot drop resulting from weakness of the anterior tibial muscle is commonly encountered in clinical practice. We analyzed the incidence of needle electromyographic (EMG) abnormalities in the anterior tibial and gastrocnemius muscles from traumatic injuries to the sciatic nerve and also from different non-traumatic lower motor neuron conditions. In both traumatic and non-traumatic cases, the anterior tibial muscle showed relatively more EMG abnormalities compared to the gastrocnemius. It appears that the anterior tibial muscle is more susceptible to injury from a variety of pathologic conditions, as opposed to the gastrocnemius muscle.

Adult↗
PubMed2001

Electromechanical dissociation in the human skeletal muscle.

It is not clear whether electromechanical dissociation can be a significant cause of clinical weakness in the human skeletal muscle. One type of muscle disorder suggests that this may occur. The condition results from the use of large doses of corticosteroids in conjunction with a neuromuscular blocking agent. In this situation, the thick myosin filaments of the sarcomere are preferentially disrupted. This may selectively compromise the contractile properties of the skeletal muscle fiber, without necessarily implicating the integrity of the muscle membrane. Thus, a muscle fiber might still be able to depolarize electrically, producing a membrane action potential, without necessarily generating an appropriate mechanical response.

Action Potentials↗
PubMed2001

Anodal excitation of intact peripheral nerves in humans.

The median nerves of six normal subjects were electrically stimulated at different locations on the wrist in a bipolar fashion. The evoked compound sensory nerve action potentials (CSNAPs) were recorded at the index finger. Electrical stimuli consisted of constant-current monophasic rectangular pulses. Initially, the nerve was stimulated with a cathodal current and a just supramaximal CSNAP was obtained. Then, at the same stimulus location, the nerve was excited with an anodal current. A just supramaximal response in the anodal-CSNAP was obtained, or until a maximum current of 100 mA was delivered. CSNAPs obtained from anodal excitation required several times more electrical stimulus intensity when compared to those derived from cathodal stimulation. Morphologically, they were similar, except the onset latency of the anodal-CSNAPs was approximately 0.2 to 0.3 msec early compared to that derived from cathodal stimulation. This implies that during anodal excitation, the site of nerve depolarization was not located underneath the anode, but was situated at some distance from it. Also, it appears that a minimum nerve length (10 mm or more) should be exposed to the anodal current in order to induce depolarization. A very localized application of the anodal stimulus often failed to elicit nerve depolarization.

Action Potentials↗
PubMed2000

Referral patterns of physicians requesting brain MRI procedures: a community-based study.

The results of the brain MRI procedures (n = 490) performed in a medium-sized community with a single MRI unit were reviewed. The non-neurologic medical practitioners ordered nearly as many brain scans as the neurospecialists (40.8% and 59.2% of the total scans respectively). The incidence of abnormal scans was 29.5% for the group of non-neurospecialists and 39.3% for the neurospecialists. A fairly large proportion (26.7%; n = 131) of the scans were requested to evaluate headaches. Twelve patients (9.2%) with headaches but without clear neurologic localizing features showed intracranial abnormalities in their MRI scans. Some of the abnormalities observed in the brain MRI scans could have been detected by a CT procedure.

Brain↗
PubMed2000

The development of a stroke clinical pathway: an experience in a medium-sized community hospital.

Patients with acute ischemic strokes were studied in a medium-sized community hospital in Mississippi. Studies were done before and after implementation of the stroke clinical care pathway with emphasis on the following clinical indicators: 1) performance of a brain CT scan, 2) the search for the etiology of the stroke, 3) whether the patient was treated emergently for hypertension, 4) the use of measures to prevent deep-vein thrombosis, and 5) prophylactic drug treatment against recurrent stroke after hospital discharge. Following application of the clinical pathway, there was a significant improvement in all the clinical indicators that were felt to require further attention and none had a setback. The length of hospital stay was decreased, and there was no significant increase in the hospital costs in the post-pathway study despite an increase in the number of diagnostic and therapeutic procedures performed. When applied properly, clinical pathways can effectively mobilize hospital resources, maximize quality of care, and at the same time minimize costs.

Aged↗
PubMed1991

Far-field recording of compound muscle action potentials produced during brachial plexus stimulation.

In 15 normal subjects, compound muscle action potentials (CMAPs) produced during electrical stimulation of the brachial plexus were obtained at a distance (far field) from their sources (upper-limb muscles). These far-field CMAPs were recorded at the forehead, neck, and tip of the middle finger and were referred to a relatively inactive region (contralateral forearm or knee). At the proximal recording site (neck or forehead), the far-field CMAPs were generally triphasic in appearance when all of the muscles of the upper limb were activated during brachial plexus stimulation. The initial component was a negative wave; this was followed by a positive component which terminated in a negative potential. At the distal recording site (tip of middle finger), the far-field CMAPs usually had a biphasic appearance, with an initial positivity followed by a period of negativity. The contours of the major components of the far-field CMAPs were frequently interrupted by a series of small amplitude negative and positive peaks or inflections.

Action Potentials↗
PubMed1991

Construction of an electrode for intraoperative nerve stimulation.

The electrode described in this paper consist of a barrel or handle with its conducting cable and a detachable stimulating tip. It is constructed of inexpensive and commercially available materials and is disposable. During the course of a stimulation study, electrode tips of different lengths or curvatures may be substituted without the need to replace the electrode barrel and cable.

Electric Stimulation↗
PubMed1990

Pathologic findings in brains of patients with focal epileptic seizures who had a craniotomy procedure.

This report reviews the pathologic findings in brains of 12 patients with focal epileptic seizures who had a craniotomy procedure. A majority of patients (seven) had either a cerebral neoplasm or a developmental abnormality (tuberous sclerosis and hamartoma), and these were found in six of the nine patients with chronic and intractable seizures. Four patients had cortical gliosis or scarring, and one had a bacterial brain abscess. Ten patients had a visible focal structural lesion during cranial imaging procedures, and in two instances, the MRI study was more sensitive than the CT in detecting a cerebral lesion.

Adolescent↗