Acute effects of alcohol on auditory brainstem potentials in humans.

Auditory brainstem potentials were recorded from human subjects before and after an intoxicating dose of alcohol. Following alcohol ingestion there were significant, progressive increases in the latencies of brainstem potential peaks III through VII. No changes in peak amplitudes were found. The results indicate that alcohol has a depressive effect on neural transmission within the primary auditory brainstem pathway.

The natural history of neurological manganism over 18 years.

We investigated the clinical features and progression of four patients with chronic manganese intoxication, 18 years after cessation of exposure. Because the results were to be compared with previous observations, we employed the same scoring system. The clinical manifestations were foot dystonia, wide based gait, rigidity, and difficulty in walking backwards. Resting tremor was rarely seen, but tongue tremor was found in 2 patients. The asymmetry initially present in 2 patients persisted 18 years later. Measurements had previously revealed rapid progression in the initial 10 years. We found a plateau over the following decade.

Functional MR imaging of the human sensorimotor cortex after toe-to-finger transplantation.

BACKGROUND: A model of toe-to-finger transplantation has been used in studying peripheral nerve regeneration and central reorganization. It was found that recovery of sensory perception depends not only on peripheral reinnervation but also on central integrative mechanisms. OBJECTIVE: Our aim was to investigate functional changes of the brain and somatotopic representation of the transplanted toes after toe-to-finger transplantation. MATERIALS AND METHODS: Six patients who had toe-to-finger transplantation from 3 to 8 years earlier underwent motor and sensory functional MR imaging studies of transplanted toes and opposite corresponding normal fingers. The motor task was performed by repetitively tapping of the transplanted toe or finger against the thumb, whereas the sensory task was applied by tactilely stimulating the pulp of the transplanted toe or finger. RESULTS: The main activation areas from both types of stimulations were located in the expected location of the finger homunculus of the primary sensorimotor cortex. In addition, activated volumes from the transplanted toes were significantly greater than those from the opposite fingers (P = .017 for motor task and P = .005 for tactile sensory task, paired samples Student t test). CONCLUSIONS: Functional recruitment in the primary sensorimotor cortex seemed to have occurred following toe-to-finger transplantation. The transplanted toe was somatotopically represented in the hand area.

Periodic lateralized epileptiform discharges with preexisting focal brain lesions. Role of alcohol withdrawal and anoxic encephalopathy.

Periodic lateralized epileptiform discharges (PLEDs) occurred in three patients during alcohol withdrawal, in two patients with episodes of anoxic ischemia, and in one patient under both conditions. In contrast to previous observations that PLEDs are often associated with acute gross destructive lesions, autopsy results and neurological studies reported here indicated that alcohol withdrawal and/or anoxic ischemia may activate preexisting focal hemispheric lesions to produce PLEDs.

Tuberculous meningitis. Computerized tomographic manifestations.

In a verified case of tuberculous meningitis, computerized tomographic scans showed a striking postcontrast enhancement of the cisterns around the base of the brain and the brainstem as well as the cortical meninges. Hydrocephalus and an infarct presumably from panarteritis were also demonstrated.

Auditory brain stem potentials in chronic alcohol intoxication and alcohol withdrawal.

Auditory brain stem evoked responses were in unrestrained rats during periods of acute and chronic alcohol intoxication, alcohol withdrawal, and recovery. Acute alcohol administration altered the auditory brain stem potentials by a prolongation of both peak latency and central conduction time, beginning with early peaks. Similar but lesser effects affecting only the latter peaks were observed during chronic alcohol intoxication. By contrast, alcohol withdrawal resulted in a decrease in the peak latencies of auditory brain stem potentials and a facilitation of central conduction time. Recovery of the auditory brain stem potentials to the normal form required at least three to four weeks. The present study provides the first quantitative data, to our knowledge, on manifestations of alcohol tolerance and withdrawal.

Chronic manganese intoxication.

We report six cases of chronic manganese intoxication in workers at a ferromanganese factory in Taiwan. Diagnosis was confirmed by assessing increased manganese concentrations in the blood, scalp, and pubic hair. In addition, increased manganese levels in the environmental air were established. The patients showed a bradykinetic-rigid syndrome indistinguishable from Parkinson's disease that responded to treatment with levodopa.

Carbamazepine: prevention of alcohol withdrawal seizures.

Effects of carbamazepine on alcohol withdrawal seizures and symptoms were studied in rats. Carbamazepine was administered during alcohol feeding and continued during alcohol withdrawal. When carbamazepine serum levels were above 3 micrograms per milliliter, alcohol withdrawal seizures were not observed. Carbamazepine also alleviated alcohol withdrawal symptoms, especially heightened spontaneous activity, startle to noise, stereotyped chewing movements, and intermittent body stiffening.

Focal seizures and aminophylline.

Intravenous aminophylline therapy for acute exacerbation of chronic obstructive pulmonary disease may trigger prolonged and difficult to control focal motor seizures with generalization. This can occur in previously neurologically asymptomatic patients and be associated with a poor outcome. Most patients exhibited periodic lateralized epileptiform discharges or had autopsy-proved focal central nervous system lesions, or both. If focal and generalized seizures develop during aminophylline therapy, drug toxicity should be suspect as announcing a focal central lesion. Careful individual monitoring of aminophylline dose and administration rate is essential.

Bilateral cortical representation of the intrinsic lingual muscles.

Motor potentials of the intrinsic lingual muscles were recorded by surface electrode in a patient with left hypoglossal neuropathy. Electrical stimulation of the right hypoglossal nerve had contralateral lingual muscle potentials representing the crosstalk volume conducted electromyography signals. Magnetic stimulation of either cerebral hemisphere yielded motor responses on the right half of the tongue with more contribution from the crossed corticobulbar fibers. Follow-up studies showed an improvement of dysphagia and left lingual motor potentials.

Manganism and idiopathic parkinsonism: similarities and differences.

From the comparison we have made between PD and manganism, we draw the following conclusions: 1. There are similarities between PD and manganism, notably the presence of (a) generalized bradykinesia and (b) widespread rigidity. 2. There are also dissimilarities between PD and manganism, notably the following in manganism: (a) less-frequent resting tremor, (b) more frequent dystonia, (c) a particular propensity to fall backward, (d) failure to achieve a sustained therapeutic response to levodopa, and (e) failure to detect a reduction in fluorodopa uptake by PET. Further studies are likely to yield more discriminants between PD and manganism. For example, PET with raclopride may be useful in early cases of manganism, and MRI may be helpful in patients with advanced manganism.

Levodopa failure in chronic manganism.

We report a placebo-controlled study of levodopa in four patients with extrapyramidal deficits caused by chronic manganese intoxication. Their parkinsonism and dystonia had progressed slowly over a period of 5 years after they left the site of exposure. Initially the patients appeared to respond to levodopa in open observations, but this apparent benefit was not sustained. This short-term, double-blind study indicates that their parkinsonism and dystonia failed to respond to levodopa.

Long-term progression in chronic manganism: ten years of follow-up.

We studied the long-term clinical course of five patients with chronic manganese intoxication. The mean scores of the King's College Hospital Rating Scale for Parkinson's disease increased from 15.0 +/- 4.2 in 1987 to 28.3 +/- 6.70 in 1991 and then to 38.1 +/- 12.9 in 1995. The deterioration was most prominent in gait, rigidity, speed of foot tapping, and writing. Tissue concentrations of manganese in blood, urine, scalp hair, and pubic hair returned to normal. Follow-up MRIs did not show paramagnetic high-signal intensity on T1-weighted images. The data indicate that clinical progression in patients with manganese parkinsonism continues even 10 years after cessation of exposure.

Progression after chronic manganese exposure.

We report a longitudinal follow-up study on six patients with chronic manganese-induced parkinsonism following cessation of manganese exposure. Compared with the 1987 study, their parkinsonian symptoms showed a slow progression, particularly in gait disturbances such as freezing during turning and walking backward with retropulsion. The mean disability scores on the King's College Hospital Rating Scale were 15.0 +/- 4.2 in 1987 and 28.3 +/- 6.7 in 1991 (p = 0.003, paired t test). Review of the video records also confirmed a worsening of parkinsonism, especially in difficulty turning. Three of six patients receiving levodopa treatment had an initial improvement. The response decreased after 2 to 3 years. During the therapy, they did not develop on-off fluctuation or dyskinesia. We conclude that patients with manganese-induced parkinsonism may develop increasing neurologic dysfunction long after cessation of exposure and that their responses to levodopa are different from those of patients with Parkinson's disease.

Presynaptic and postsynaptic striatal dopaminergic function in patients with manganese intoxication: a positron emission tomography study.

We performed PET on four patients with chronic industrial Mn intoxication; presynaptic and postsynaptic dopaminergic function were measured with [18F]6-fluoro-L-dopa (6FD) and [11C]raclopride (RAC). All patients had a rigid-akinetic syndrome; they had no sustained benefit from L-dopa. Influx constants (Ki) of 6FD were normal in the caudate and putamen. RAC binding was mildly reduced in the caudate and normal in the putamen. We conclude that nigrostriatal dopaminergic dysfunction is not responsible for the parkinsonism caused by chronic Mn intoxication. The pathology is likely to be downstream of the dopaminergic projection.

Levels of naturally occurring microorganisms on surgical instruments after clinical use and after washing.

Surgical instruments exposed to sterile body sites should be contaminated with relatively low levels of microbial contamination or bioburden; however, few studies in the literature have determined the quantitative level and types of contamination. A study was conducted at 2 clinical sites to determine the level of microbial contamination of surgical instruments after clinical use and after washing. Quantitative assays showed that bioburden levels were in the range of 0 to 4415 colony forming units per instrument after clinical use, and 88% of the instruments had bioburden levels lower than 1000. As expected, a reduction in counts occurred after washing; however, in some cases, higher counts were found on the instruments after the washing process. Although the washing procedure is effective in reducing the microbial levels deposited on the surgical instruments during use, a recontamination process occurs that results in increased counts after washing. The low bioburden level after washing consists of predominantly vegetative microorganisms that present a relatively low challenge to sterilization and disinfection systems.

Phantom finger phenomena and the effects of toe-to-finger transplantation.

Phantom finger phenomena and the effects of toe-to-finger transplantation were studied in 76 patients who had had traumatic finger amputation. Phantom finger phenomena were observed in 48 (63%) patients with the presence of phantom finger only in 30, phantom finger with sensation in nine, and phantom finger with motion also in nine. After toe transplantation, phantom finger phenomena disappeared immediately in about half of the transplanted fingers that had phantom phenomena before toe transplantation, and also in about half of the amputated fingers without the surgery. Conversely, phantom toe phenomena occurred in 13 (17%) patients. Although some patients had mild-to-moderate unpleasant phantom sensations, none had severe or distressing phantom finger pain or phantom toe pain. It is concluded that phantom phenomena occurred in both finger and toe amputations, and that toe-to-finger transplantation appeared to facilitate the disappearance of phantom phenomena not only in the transplanted fingers but also in the amputated but untransplanted fingers. Possible mechanisms for these observations are discussed.

Responses of midbrain raphe neurons to ethanol.

The effects of ethanol on single midbrain raphe neurons were studied in the rat. For dorsal raphe neurons, only the units with rhythmic slow firing were consistently inhibited by ethanol. Those units often exhibited periodic cessation of spontaneous discharges in the initial responses, but later showed a dose-related slowing of discharge rates. Although median raphe neurons were also inhibited by ethanol, their responses consisted of an early tendency to fire more regularly, and then a decrease in spontaneous activity with bursting discharges. The data indicate that ethanol exerts different modes of inhibition on these two functionally different cell groups in the midbrain raphe complex.

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.

Short- and long-latency tibial somatosensory evoked potentials in cerebral lesions affecting Rolandic leg areas.

Short- and long-latency tibial somatosensory evoked potentials (SEPs) were studied in nine patients with clinical presentation primarily involving one lower extremity. In group 1, with extensive infarcts in the territory of anterior cerebral artery, tibial cortical SEPs were uniformly absent. In group 2, with small infarcts involving Rolandic leg areas, tibial SEPs showed a decrease in overall response amplitude and attenuation of P40. In group 3, with discrete mass lesions compressing Rolandic leg areas, P40 was preserved but might be delayed. Late SEP components (N75, P100 and N135) tended to be preserved in the patients of group 2 and 3. The data suggest that Rolandic leg areas and the neighboring cortex are crucial for short- and long-latency tibial cortical SEPs and that small lesions affecting Rolandic leg areas tend to affect short- and mid-latency SEP components.