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Biomedical subjects

S G Reich

Publications and source records attributed to S G Reich.

At least 19 recordsLinked to original sources
PubMed2001

Suppression of post-hypoxic and post-encephalitic myoclonus with levetiracetam.

Posthypoxic and postencephalitic myoclonus is often poorly controlled with current treatments. The authors successfully treated three patients with posthypoxic and postencephalitic myoclonus by using levetiracetam, a new antiepileptic drug. Levetiracetam appears to be a promising agent for treating action myoclonus caused by hypoxic and encephalitic brain injury-the degree of functional improvement may depend on the severity of associated motor dysfunction.

Adult↗
PubMed2000

Hereditary spastic paraplegia and hereditary ataxia, Part 2: A family demonstrating various phenotypic manifestations with the SCA3 genotype.

BACKGROUND: Clinical descriptions of the dominantly inherited ataxic motor syndromes in a 7-generation family of German origin were first reported in 1951. OBJECTIVE: To provide follow-up clinical, pathological, and genetic data for 9 patients in this family. DESIGN: Clinical histories and neurologic findings, gross and microscopic pathological features, and DNA analysis. RESULTS: Clinical presentations in this closely followed up portion of the family include fairly uniform ataxic and upper motor neuron symptoms. Nystagmus was a conspicuous and early sign, but generational anticipation was not evident. Although often present, amyotrophy was not a major source of disability. Major pathological degeneration was noted in the pons, spinal cord, and upper brainstem, where ubiquitin-immunoreactive intranuclear inclusion bodies were demonstrated. The diagnosis of Machado-Joseph disease (SCA3 [spinocerebellar ataxia type 3] genotype) was established from autopsy tissue in 1 patient and from blood specimens in 6 others. CONCLUSIONS: Clinical variation within this family and between this family and families with the SCA1 and SCA3 genotypes is so broad as to make the genetic diagnosis from clinical criteria alone practically impossible. The pathological definition of Machado-Joseph disease is more reliable, but some findings do overlap those of other genotypes. To our knowledge, the basis for the phenotypic variations in Machado-Joseph disease, genetic or otherwise, has not been established.

Adult↗
PubMed1999

PET imaging of the dopamine transporter in progressive supranuclear palsy and Parkinson's disease.

OBJECTIVE: To differentiate the patterns of dopamine transporter loss between idiopathic PD and progressive supranuclear palsy (PSP). METHODS: We used the radiotracer [11C]-WIN 35,428 and PET. Regional striatal dopamine transporter binding was measured in the caudate, anterior putamen, and posterior putamen of six patients with L-dopa-responsive stage 2 PD, six patients with PSP, and six age-comparable healthy controls. RESULTS: In patients with idiopathic PD, the most marked abnormality was observed in the posterior putamen (77% reduction), whereas transporter density in the anterior putamen (60% reduction) and the caudate (44% reduction) was less affected. Unlike the patients with PD, the PSP group showed a relatively uniform degree of involvement in the caudate (40% reduction), anterior putamen (47% reduction), and posterior putamen (51% reduction). When posterior putamen/caudate ratios were calculated, these values were significantly lower in patients with PD than they were in patients with PSP (p = 0.0008) and the control group (p < 0.0001). CONCLUSIONS: Patients with PD have a more pronounced loss of dopamine transporters in the posterior putamen due to a subdivisional involvement of nigrostriatal dopaminergic projections in idiopathic PD. This technique is useful in the determination of neurochemical changes underlying PD and PSP, thus differentiating between them.

Carbon Radioisotopes↗
PubMed1999

Stereotactic thalamotomy in the treatment of essential tremor of the upper extremity: reassessment including a blinded measure of outcome.

The effectiveness of high frequency stimulation of the thalamic nucleus ventralis intermedius (Vim-HFS) for treatment of tremor has been studied by blinded assessment. The effectiveness of thalamotomy for essential tremor of the upper extremity by use of a blinded measure of outcome is now reported. Thalamotomy was performed in 21 patients (three operated on bilaterally) with medically intractable, essential tremor. Assessments of function, handwriting/drawing, and tremor amplitude were done before and at 3 and 12 months after surgery. The handwriting/drawing score was rated by a neurologist blinded to patient identity, laterality, and operative status. By comparison with baseline, both the total functional score and the total score from blinded assessment of handwriting/drawing improved significantly at 3 and 12 months after surgery. The two scores were significantly correlated, suggesting that the blinded assessment is a good predictor of a total disability from tremor. Complications after unilateral thalamotomy included transient dysarthria, permanent perioral numbness, and permanent mild disequilibrium in one patient each. Permanent mild dysarthria occurred in two of three patients operated bilaterally. Thus a blinded assessment of outcome establishes that unilateral thalamotomy is an effective, safe procedure for the treatment of essential tremor.

Aged↗
PubMed1999

Thalamic single neuron activity in patients with dystonia: dystonia-related activity and somatic sensory reorganization.

Indirect evidence suggests that the thalamus contributes to abnormal movements occurring in patients with dystonia (dystonia patients). The present study tested the hypothesis that thalamic activity contributes to the dystonic movements that occur in such patients. During these movements, spectral analysis of electromyographic (EMG) signals in flexor and extensor muscles of the wrist and elbow exhibited peak EMG power in the lowest frequency band [0-0.78 Hz (mean: 0.39 Hz) dystonia frequency] for 60-85% of epochs studied during a pointing task. Normal controls showed low-frequency peaks for <16% of epochs during pointing. Among dystonia patients, simultaneous contraction of antagonistic muscles (cocontraction) at dystonia frequency during pointing was observed for muscles acting about the wrist (63% of epochs) and elbow (39%), but cocontraction was not observed among normal controls during pointing. Thalamic neuronal signals were recorded during thalamotomy for treatment of dystonia and were compared with those of control patients without motor abnormality who were undergoing thalamic procedures for treatment of chronic pain. Presumed nuclear boundaries of a human thalamic cerebellar relay nucleus (ventral intermediate, Vim) and a pallidal relay nucleus (ventral oral posterior, Vop) were estimated by aligning the anterior border of the principal sensory nucleus (ventral caudal, Vc) with the region where the majority of cells have cutaneous receptive fields (RFs). The ratio of power at dystonia frequency to average spectral power was >2 (P < 0.001) for cells in presumed Vop often for dystonia patients (81%) but never for control patients. The percentage of such cells in presumed Vim of dystonia patients (32%) was not significantly different from that of controls (31%). Many cells in presumed Vop exhibited dystonia frequency activity that was correlated with and phase-advanced on EMG activity during dystonia, suggesting that this activity was related to dystonia. Thalamic somatic sensory activity also differed between dystonia patients and controls. The percentage of cells responding to passive joint movement or to manipulation of subcutaneous structures (deep sensory cells) in presumed Vim was significantly greater in patients with dystonia than in control patients undergoing surgery for treatment of pain or tremor. Dystonia patients had a significantly higher proportion of deep sensory cells responding to movement of more than one joint (26%, 13/52) than did "control" patients (8%, 4/49). Deep sensory cells in patients with dystonia were located in thalamic maps that demonstrated increased representations of parts of the body affected by dystonia. Thus dystonia patients showed increased receptive fields and an increased thalamic representation of dystonic body parts. The motor activity of an individual sensory cell was related to the sensory activity of that cell by identification of the muscle apparently involved in the cell's receptive field. Specifically, we defined the effector muscle as the muscle that, by contraction, produced the joint movement associated with a thalamic neuronal sensory discharge, when the examiner passively moved the joint. Spike X EMG correlation functions during dystonia indicated that thalamic cellular activity less often was related to EMG in effector muscles (52%) than in other muscles (86%). Thus there is a mismatch between the effector muscle for a thalamic cell and the muscles with EMG correlated with activity of that cell during dystonia. This mismatch may result from the reorganization of sensory maps and may contribute to the simultaneous activation of multiple muscles observed in dystonia. Microstimulation in presumed Vim in dystonia patients produced simultaneous contraction of multiple forearm muscles, similar to the simultaneous muscle contractions observed in dystonia. (ABSTRACT TRUNCATED)

Brain Mapping↗
PubMed1998

The role of the thalamus and basal ganglia in parkinsonian tremor.

The mechanism of parkinsonian tremor may involve a central oscillator, peripheral feedback to the central nervous system (CNS), or both. The thalamus or the globus pallidus is the most likely site for a central oscillator and would be predicted to generate thalamic tremor-related activity characterized, respectively, by calcium spike-associated bursts and by maximal tremor-related activity in the pallidal relay nucleus of thalamus. Thalamic spike trains demonstrate neither of these characteristics. However, cross-correlation, latency, and transfer function analysis indicate that sensory feedback is a critical element in the relationship between thalamic activity and parkinsonian tremor. Therefore, thalamic spike train activity is most consistent with parkinsonian tremor being mediated by peripheral inputs involved in either an unstable reflex loop or sensory modulation of a central oscillator.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1998

Patterns of bursting occurring in thalamic cells during parkinsonian tremor.

It has been proposed that parkinsonian tremor is produced either by the activity of an intrinsic thalamic pacemaker or by the oscillation of an unstable long loop reflex arc. The former (central) hypothesis proposes that overactivity of neurons in the internal segment of the globus pallidus inhibits or hyperpolarizes thalamic neurons. When hyperpolarized, thalamic cells oscillate with bursting of the type associated with low threshold calcium spikes (low threshold spike-bursts). Low threshold spike-bursts can be identified by particular patterns of interspike intervals within the burst. The alternative (peripheral) hypothesis proposes that tremor results from oscillation of a reflex arc transmitting activity from muscle stretch receptors to thalamus, motor cortex, and back to the stretched muscle. When the gain of this reflex is increased, the arc may become unstable and oscillate. Oscillations produced by peripheral inputs may produce an acceleration-deceleration pattern within the burst which results in sinusoidal modulation of a spike train if bursting is periodic. We have assessed these two hypotheses by studying the pattern of interspike intervals occurring within bursts recorded in patients with parkinsonian tremor. The spike trains were analysed for 118 cells located in the ventral nuclear group including ventralis intermedius (thalamic cerebellar relay nucleus, n=48) and ventralis oralis posterior (thalamic pallidal relay nucleus, n=39) of patients with parkinsonian tremor. Two cells recorded in ventralis intermedius of a sleeping patient with chronic pain showed bursting activity similar to the low threshold spike-bursts recorded in sleeping animals, suggesting a common mechanism for low threshold spike-bursts across species. Forty-two cells recorded in patients with parkinsonian tremor (ventralis intermedius, n=19; ventralis oralis posterior, n=12) were classified as tremor-related cells because their activity was characterized by both a concentration of power at tremor frequency and significant correlation with tremor. Eleven tremor-related cells, 10 located in ventralis intermedius or ventralis oralis posterior and most responding to sensory inputs, had an acceleration-deceleration pattern of intraburst firing. Only one cell, a tremor-related cell in ventralis intermedius, showed the pattern expected of presumed low threshold spike-bursts. Therefore, intraburst interspike interval patterns consistent with either the central or the peripheral hypothesis were recorded in the thalamus of patients with parkinsonian tremor. Twenty-one tremor-related cells (15 cells in ventralis intermedius or ventralis oralis posterior) had bursts with intraburst interspike intervals which were independent of position of the interspike interval within the burst. Therefore, the activity of the majority of cells was not consistent with either hypothesis, suggesting that another oscillatory process may contribute to parkinsonian tremor.

Electromyography↗
PubMed1998

Thalamic neuronal activity correlated with essential tremor.

Animal studies suggest that an olivocerebello-bulbospinal pathway mediates harmaline induced tremor, which resembles essential tremor in humans. However, recent evidence suggests that thalamocortical pathways participate in essential tremor. Thalamic single neuron activity has been analysed during thalamotomy for essential tremor. It has been shown by spectral cross correlation analysis that thalamic activity has a significant, linear relation to forearm EMG activity during tremor. The presence of this tremor related activity at the site where a lesion abolishes essential tremor suggests that the thalamus has an important role in the mechanism of essential tremor.

Adult↗
PubMed1998

Pallidal activity during dystonia: somatosensory reorganisation and changes with severity.

A woman with progressive, medically intractable right upper limb dystonia underwent a pallidotomy with only transient improvement. During the procedure her dystonia became more severe as she repeatedly made a fist to command in order to provoke dystonia transiently (movement provoked dystonia). Comparisons within cells in the internal segment of the globus pallidus (Gpi) disclosed that the firing rate was the same at rest, with making a fist, and during movement provoked dystonia. However, the firing rate compared between cells decreased significantly throughout the procedure as the patient made a fist repeatedly. During the second half of the procedure the firing rate of cells in the Gpi was similar to that in hemiballismus. The proportion of cells in the GPi which responded to sensory stimulation was significantly higher in dystonia (53%) than in hemiballismus (13%). These results suggest that pallidal activity can correlate inversely with the severity of dystonia, perhaps due to activity dependent changes in neuronal function resulting from repeated voluntary movement.

Antiparkinson Agents↗
PubMed1998

Pachymeningitis with multiple cranial neuropathies and unilateral optic neuropathy secondary to Pseudomonas aeruginosa: case report and review.

Hypertrophic cranial pachymeningitis is a rare disorder that frequently presents with multiple cranial neuropathies. This disorder, which is characterized by thickening and infiltration of the cranial dura, can result from a variety of inflammatory and infectious conditions. A patient with hypertrophic cranial pachymeningitis is described in whom meningeal biopsy and bacterial cultures of the biopsy specimen revealed Pseudomonas aeruginosa. The authors believe this to be the first documented case of pachymeningitis secondary to this organism.

Ceftazidime↗
PubMed1997

Adaptive Fourier modeling for quantification of tremor.

A new computational method for quantification of tremor, the weighted frequency Fourier linear combiner (WFLC), is presented. This technique rapidly determines the frequency and amplitude of tremor by adjusting its filter weights according to a gradient search method. It provides continual tracking of frequency and amplitude modulations over the course of a test. By quantifying time-varying characteristics, the WFLC assists in correctly interpreting the results of spectral analysis, particularly for recordings exhibiting multiple spectral peaks. It therefore supplements spectral analysis, providing a more accurate picture of tremor than spectral analysis alone. The method has been incorporated into a desktop tremor measurement system to provide clinically useful analysis of tremor recorded during handwriting and drawing using a digitizing tablet. Simulated data clearly demonstrate tracking of variations in frequency and amplitude. Clinical recordings then show specific examples of quantification of time-varying aspects of tremor.

Algorithms↗
PubMed1997

Pallidotomy for hemiballismus: efficacy and characteristics of neuronal activity.

A patient with unremitting, medically intractable hemiballismus underwent a pallidotomy that abolished his involuntary movements. Firing rates of cells in the internal segment of the globus pallidus (GPi) recorded during this procedure were significantly lower than those observed during pallidotomy for Parkinson's disease, either "on" or "off" medication. Firing patterns in hemiballismus were characterized by low-frequency modulation of the firing rate. These results are consistent with the hyperkinetic model, which suggests that hemiballismus results from decreased inhibition of the pallidal relay nucleus of the thalamus by the GPi. The efficacy of surgery in the case of hemiballismus demonstrates that pallidotomy can be an effective treatment for this condition and suggests that patterned neuronal activity in the GPi is important in the mechanism of hyperkinetic disorders.

Action Potentials↗
PubMed1996

The dynias.

The "dynias" are a group of chronic, focal pain syndromes with a predilection for the orocervical and urogenital regions. They include glossodynia, carotidynia, vulvodynia, orchidynia, prostatodynia, coccygodynia, and proctodynia. In some cases, the dynias occur secondarily, but more often, despite an exhaustive evaluation, no etiology is found and in these remaining cases, the cause of the pain remains enigmatic. The controversy that surrounds this group of disorders, which ranges from questioning their existence to suggesting that they are purely psychosomatic, is counterbalanced by an extensive literature attesting to their organicity. The approach to the patient begins with acknowledging that the symptom is well described, searching for a secondary cause, and performing a careful psychologic assessment. Treatment is empirical and patients can often be helped with medications used to treat neuropathic pain, all the while providing psychologic support and exercising caution toward invasive and irreversible therapeutic procedures.

Adult↗
PubMed1996

The menagerie of migraine.

Migraine is conventionally regarded as a specific type of headache with a small set of associated neurologic symptoms. Yet, the true scope and frequency of migrainous phenomena are much greater than is generally acknowledged. Six cases are presented to illustrate some of the diverse manifestations of migraine: (1) transient global amnesia, (2) persistent visual phenomena, (3) migraine and seizures, (4) vestibular dysfunction, (5) hearing loss, and (6) migraine masquerading as multiple sclerosis. These and other migraine-associated neurologic symptoms are discussed in relation to previous reports in the literature. Pitfalls in recognizing the diverse manifestations of migraine, which are often underdiagnosed or misdiagnosed, are reviewed. Whether or not the established diagnostic criteria for migraine are too strict, other factors contributing to failure to identify migraine when it causes nonclassic neurologic symptoms include: (1) the belief that these are rare, (2) lack of an objective measure for migraine, (3) inadequate attention to the positive diagnostic features of migraine in the absence of headache, (4) confusion regarding prior migraine history, and (5) dismissing the diagnosis because of reported failure of prior migraine treatment. Recognition of the diversity of migraine helps avoid unnecessary testing and opens the door to effective treatment.

Adult↗
PubMed1993

Positron emission tomographic imaging of the dopamine transporter with 11C-WIN 35,428 reveals marked declines in mild Parkinson's disease.

Parkinson's Disease (PD) is characterized by a selective loss of nigrostriatal dopaminergic neurons that results in a marked reduction of dopaminergic nerve terminals in the striatum. Recently, 11C-WIN 35,428, a cocaine analogue that specifically labels the dopamine transporter, was developed and can be used to label dopaminergic nerve terminals in vivo by positron emission tomography. In healthy control subjects, binding of 11C-WIN 35,428 is highest in the striatum. In addition, 2 symmetrical focal areas of low binding were observed in the midbrain. The cerebellum functioned as an appropriate region for nonspecific binding. The binding of 11C-WIN 35,428 in patients with PD (Hoehn-Yahr II) was compared with that in healthy control subjects by using the (region-cerebellum)/cerebellum ratio for data acquired 34 to 82 minutes after injection. In control subjects, this ratio varied, at approximately 2, in the striatum. In patients with PD, binding in the posterior putamen was reduced by 78%, whereas the anterior putamen and the caudate nucleus showed a reduction of 59 and 39%, respectively. The reduction in 11C-WIN 35,428 binding was highest in the midbrain (84%). The high specific/nonspecific binding ratio and the pronounced reduction in binding in mild PD may permit detection of even earlier stages of PD or presymptomatic individuals with dopaminergic cell loss.

Biomarkers↗