Effects of Betel chewing on the central and autonomic nervous systems.

Betel chewing has been claimed to produce a sense of well-being, euphoria, heightened alertness, sweating, salivation, a hot sensation in the body and increased capacity to work. Betel chewing also leads to habituation, addiction and withdrawal. However, the mechanisms underlying these effects remain poorly understood. Arecoline, the major alkaloid of Areca nut, has been extensively studied, and several effects of betel chewing are thought to be related to the actions of this parasympathomimetic constituent. However, betel chewing may produce complex reactions and interactions. In the presence of lime, arecoline and guvacoline in Areca nut are hydrolyzed into arecaidine and guvacine, respectively, which are strong inhibitors of GABA uptake. Piper betle flower or leaf contains aromatic phenolic compounds which have been found to stimulate the release of catecholamines in vitro. Thus, betel chewing may affect parasympathetic, GABAnergic and sympathetic functions. Betel chewing produces an increase in heart rate, blood pressure, sweating and body temperature. In addition, EEG shows widespread cortical desynchronization indicating a state of arousal. In autonomic function tests, both the sympathetic skin response and RR interval variation are affected. Betel chewing also increases plasma concentrations of norepinephrine and epinephrine. These results suggest that betel chewing mainly affects the central and autonomic nervous systems. Future studies should investigate both the acute and chronic effects of betel chewing. Such studies may further elucidate the psychoactive mechanisms responsible for the undiminished popularity of betel chewing since antiquity.

Correlation of neurological manifestations and MR images in a patient with Wilson's disease after liver transplantation.

Orthotopic liver transplantation (OLT) has been applied to patients with Wilson's disease (WD) for correction of irreversible liver cirrhosis. However, the neurological outcome and the correlation between clinical manifestations and neuroimage findings after OLT remain uncertain. We present a WD patient who showed an improvement in both liver functions and neurological manifestations after OLT. Serum levels of ceruloplasmin and copper returned to normal rapidly after the operation. His ataxic gait was improved 5 months later and dysmetria and tremor disappeared 11 months later. The high signal intensities on T2-weighted brain magnetic resonance images regressed at bilateral thalami 5 months later and disappeared in bilateral thalami and red nuclei 16 months after OLT. We conclude that the neurological improvement could be expected in WD patients after OLT. The improvement was correlated with the MRI changes in red nuclei and bilateral thalami.

Betel chewing increases the skin temperature: effects of atropine and propranolol.

Although betel chewing produces sweating, facial flush and a warm sensation of the body, objective documentation of the temperature effect has not been available. In this report, the skin temperature of the ear and forehead was recorded before and during betel chewing in healthy betel chewers. Betel chewing produced a mean temperature increase of 2 degrees C and 0.5 degree C, respectively, for the ear and forehead. This hyperthermic response was almost completely abolished by atropine and partially inhibited by propranolol. The present data suggest that both sympathetic and parasympathetic mechanisms are involved in the skin thermal response to betel chewing.

Effect of betel chewing on RR interval variation.

Betel chewing in man often produces palpitations, sweating, facial flushing and a warm sensation in the body. These observations suggest that betel chewing may affect the autonomic nervous system. To examine this, the RR interval variation (RRIV) was studied to determine if betel chewing might affect parasympathetic function. Three experimental groups of people consumed a betel nut preparation, betel quid and chewing gum, respectively. Recordings of RRIV were made before and during chewing. When one or two betel nut preparations were consumed, the main effect was a cardioacceleratory response. With increasing consumption of betel nut preparation, there was a reduction in RRIV, particularly during deep breathing. Consumption of betel quid or chewing gum had no effect on RRIV. The effect of betel chewing was dose-dependent. Consumption of a small amount caused cardioacceleratory response suggesting a sympathetic activation, while consumption of a large amount reduced RRIV, suggesting involvement of the parasympathetic function.

Effect of betel chewing on performance reaction time.

To test the validity of claims by users that betel chewing heightens alertness and improves motor responses, the effect of betel chewing on simple and choice reaction times (SRT and CRT) was investigated in habitual users. Control consisted of chewing gum and practice groups. Both SRT and CRT were correlated with age. In the SRT task, reaction times were not different among the three groups studied. In the CRT task, only betel and chewing gum groups showed a significant shortening of reaction time, but the betel group had a higher degree of statistical significance in this effect. It is concluded that shortening of CRT from betel chewing is probably partly due to chewing itself and partly due to a cholinergic arousal mechanism.

Sympathetic skin responses to betel chewing.

The sympathetic skin response of habitual betel users was studied to determine the effect of betel chewing on sympathetic function. Sympathetic skin response was recorded from the hand by stimulation of the contralateral median nerve at the wrist. While the response latency remained unchanged, the response amplitude showed a progressive reduction during chewing and a gradual recovery after chewing. The present data suggest that betel chewing probably affects sympathetic function through a cholinergic action at the central generator sites.

Effects of betel chewing on electroencephalographic activity: spectral analysis and topographic mapping.

The effect of betel chewing on the electroencephalographic (EEG) activity of 52 betel users was studied by spectral analysis and topographic mapping before and during betel chewing. Betel chewing increased both alpha and beta activities but decreased theta activity. These effects were most prominent for beta rhythm. Topographic mapping revealed that altered spectral rhythms were restricted to the occipital areas for the alpha band but were more widespread for both theta and beta bands. The present data suggest that betel chewing causes EEG changes associated with a state of arousal and to a lesser degree a state of relaxation.

Cardiovascular responses to betel chewing.

The cardiovascular effects of betel nut were studied in 47 healthy male subjects who were divided into three groups: chronic, occasional and new chewers. Cardiovascular responses measured included heart rate and blood pressure changes following betel chewing. All three groups showed a significant increase in heart rate lasting an average of 16.8 minutes. On the other hand, only the new chewer group showed an increase in systolic blood pressure. Present data indicate that betel chewing can affect cardiovascular function, and that tolerance to the pressor response may occur in habitual users.

A simultaneous comparison of acupuncture needle and insulated needle sphenoidal electrodes for detection of anterior temporal spikes.

Uninsulated acupuncture needles have been used as sphenoidal electrodes, but the issue of insulation has not been adequately addressed. In this report, acupuncture needles and insulated needle sphenoidal electrodes were simultaneously used to compare the rate of spike detection, spike amplitude and distribution of maximal spikes from eight spike foci in seven patients with temporal lobe epilepsy. When compared to the insulated needle electrode, the acupuncture needle electrode was equally effective in spike detection, but spike amplitudes tended to be smaller and maximal spikes were less frequently encountered. Thus, insulation has an influence on the spikes recorded by the acupuncture needle sphenoidal electrode. However, the overall effect appears to be not sufficiently different from the insulated needle electrode for the purpose of detecting anterior temporal spikes in outpatient EEG recordings for the diagnosis of temporal lobe epilepsy.

Sphenoidal EEG recording using acupuncture needle electrode in complex partial seizure.

Sphenoidal EEG recording using an uninsulated acupuncture needle electrode were performed in 41 patients with or suspected of complex partial seizures of temporal lobe origin. The anterior temporal spikes were detected by the routine EEG in 17 patients (41%) and by the acupuncture sphenoidal needle in 29 patients (70%). The anterior temporal spikes recorded by the acupuncture needle were almost identical in configuration, amplitude and distribution to those recorded by conventional wire or insulated needle sphenoidal electrodes. The sequence in the frequency of spike detection by these 3 types of sphenoidal electrode were SP1-2, T1-2, F7-8 and A1-2 locations. The spikes of maximal amplitude were most frequently recorded by the SP electrode followed by the T1-2 electrode. The placement of the disposable acupuncture needle was simple and safe. Patients experienced minimal discomfort or pain that lasted at most 0.5 h. No complications occurred. The records were generally free of artifacts. It is concluded that the acupuncture needle can be used as sphenoidal electrode in outpatient EEG recording for the diagnosis of complex partial seizures of anterior temporal-origin.

Motor evoked potentials in Wilson's disease: early and late motor responses.

Motor evoked potentials following magnetic stimulation of the motor cortex and the spinal roots were studied in 13 patients with Wilson's disease (WD). The fast-conducting motor pathway function was normal in 9 patients. The cortically-evoked motor responses were absent in patients with cerebral white matter lesion and akinetic rigid syndrome. In addition to the primary or early motor response, late motor response was common in WD and occurred with a latency of 70-90 msec for the upper limb and 90-110 msec for the lower limb. The cause of the late motor response is unknown, but may be an enhanced late response infrequently observed in normal subjects.

Thermosensitivity of dorsal raphe neurons in vitro.

Thermosensitivity of raphe neurons was studied in tissue slices of rat brainstems (400-500 micron). Measurement of activity of single cells in the dorsal raphe region of the slices revealed that the majority of neurons (89%) were sensitive to changes in temperature. Over the range 34 to 42 degrees C, 3 classes of thermosensitive cells were found: warm (61%), cold (15%) and biphasic type cells (13%). Many dorsal raphe neurons may be intrinsically temperature sensitive and may serve as extrahypothalamic thermodetector components in the integrative process of central thermoregulation.

Median and tibial somatosensory evoked potentials. Changes in short- and long-latency components in patients with lesions of the thalamus and thalamo-cortical radiations.

Alterations in short- and long-latency components of median and tibial somatosensory evoked potentials (SEPs) were studied in patients with lesions in the thalamus and thalamo-cortical radiations. When the lesions were located primarily in the ventro-posterior thalamus, the SEP changes consisted of the following combination: absence of response; decrease in response amplitude; delay in peak latency; and attenuation of median N20-P25 and tibial P40. The laterally situated ventro-posterior lesions tended to preferentially affect tibial SEPs whereas the medially situated lesions tended to preferentially affect median SEPs. The lateral thalamic lesions affected primarily the long-latency SEP components, whereas the medial thalamic lesions affected primarily the mid-latency or the mid- and long-latency SEP components. Corona radiata infarcts produced SEP changes similar to those with the ventro-posterior thalamic lesions except that absence of evoked responses was not observed. Subcortical infarcts tended to affect the mid- and long-latency SEP components with relative preservation of the short-latency components. The present data indicate that only the lesions involving the primary thalamic relay area affected all SEP components, particularly the short-latency components, and that the lesions in other thalamic areas can also influence the SEPs, particularly the mid- and long-latency components. The present study further demonstrates that a combined use of median and tibial SEPs is useful in delineating the topographic organization of the somatosensory system in the thalamus.

Auditory brain stem potentials with alcohol.

Auditory brain stem potentials were recorded from unrestrained rats and from cats paralyzed with Flaxedil, before and after ingestion of intoxicating dosages of alcohol. The acute effect of alcohol was a cumulative increase in the central conduction times of successive brain stem potential peaks. Statistically significant latency changes were found for peaks attributed to neural structures as far peripherally as the medulla. This depressive influence of alcohol on sensory transmission was independent of variations in stimulus intensity and body temperature.