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Biomedical subjects

P Krack

Publications and source records attributed to P Krack.

At least 55 records · Page 3Linked to original sources
PubMed1998

Treatment of tremor in Parkinson's disease by subthalamic nucleus stimulation.

The recent resurgent interest in functional surgery for the treatment of Parkinson's disease (PD) has focused on the effects on akinesia and levodopa-induced dyskinesia. Stimulation of the subthalamic nucleus (STN) improves akinesia and rigidity but its effects on tremor have not been studied. The objective of this study was to assess the efficacy of STN stimulation on tremor in patients with the complete parkinsonian triad with motor fluctuations. Of 27 consecutive patients with STN stimulation (26 bilateral), 15 exhibited tremor rated at least 2/4 according to item 20 (rest tremor) of the Unified Parkinson's Disease Rating Scale (UPDRS) in at least one limb. The mean preoperative tremor score was 11.3+/-5.6 in off-drug and 1.2+/-2.4 in on-drug conditions. The postoperative tremor scores at the last follow up (from 1-12 months) were 2.2+/-2.2 off-drug/on-stimulation and 0.2+/-0.4 on-drug/on-stimulation. Both rest and action tremors were improved in all patients. The UPDRS tremor score was reduced by 80%, rigidity score by 65%, and akinesia score by 51% on average. For the three symptoms, the stimulation effect was close to that induced before surgery by a suprathreshold dose of levodopa given in the morning. STN stimulation can be considered an interesting alternative to thalamic or internal pallidal surgery even in PD patients with severe high-amplitude tremor. In keeping with electrophysiological data in monkeys rendered parkinsonian by MPTP injections, our results emphasize the importance of the oscillation of a neuronal loop involving the STN in the pathophysiology of parkinsonian tremor.

Adult↗
PubMed1998

Long-term electrical inhibition of deep brain targets in movement disorders.

Stimulation of the thalamic nucleus ventralis intermedius (Vim) at high (130-Hz) frequency has been used over the last 8 years as a treatment in 134 patients with movement disorders (91 Parkinson's disease [PD], 23 essential tremor [ET], 21 various dyskinesias and dystonias, including four multiple sclerosis [MS]), implanted with long-term electrodes connected to a programmable stimulator. In PD patients, tremor was selectively suppressed for < or = 11 years. In ET patients, results were satisfactory, but in 35% of the cases deteriorated with time, when tremor had an action component. Other types of dyskinesias were much less influenced. Sixty-eight patients were bilaterally implanted, and 14 were implanted contralateral to a previous thalamotomy. Side effects were often minor, well tolerated, and immediately reversible. Three secondary scalp infections led to temporary removal of implanted material. There was no permanent morbidity. Long-term Vim stimulation, which is reversible, adaptable, and well tolerated, even by bilaterally operated-on (68 of 134) and by elderly patients, should replace thalamotomy in the regular surgical treatment of parkinsonian and essential tremors. More recently, we stimulated the subthalamic nucleus (STN) in 51 patients (44 bilateral) and the globus pallidus internus (GPi) in 12 patients (seven bilateral). STN stimulation has a spectacular effect on akinesia and rigidity and may improve the patients so as to maintain them all day at a level similar to their best "on" periods. A 30-50% reduction in drug dosage was possible in most of the patients. GPi stimulation has indications and effects similar to those of pallidectomy: abnormal involuntary movements are totally suppressed, whereas effects on akinesia and rigidity are not so important as they are with STN stimulation. For all three targets, morbidity is low and reversible, even when bilateral implantations are performed. The deep-brain stimulation method has now proved its safety as compared with ablative surgery and is able to provide a significant improvement to these severely disabled patients. Long-term follow up is establishing the security of the method, which should be considered in earlier stages of the disease actively to participate to rehabilitation.

Electric Stimulation↗
PubMed1998

Subthalamic nucleus or internal pallidal stimulation in young onset Parkinson's disease.

The aim of this study was to compare, retrospectively, the value of chronic bilateral stimulation of the internal globus pallidus (GPi) and the subthalamic nucleus (STN) in patients with young onset Parkinson's disease. We selected 13 consecutive patients with similar characteristics at the time of surgery: age at onset < 40 years, disabling motor fluctuations (Hoehn and Yahr stage 4 or 5 in off-drug phases) and levodopa-induced dyskinesias (LID). Eight patients were operated on in the STN and five in the GPi. The Unified Parkinson's Disease Rating Scale (UPDRS), timed motor tests and a LID scale were compared in on- and off-drug conditions before surgery and 6 months after surgery on stimulation using the chronic electrical parameters found to improve best the motor state of the individual patient, without adverse effects. In off-drug phases, the motor score of the UPDRS was improved by 71% with STN stimulation and by 39% with GPi stimulation on average. This difference was statistically significant (P < 0.05). Whereas rigidity and tremor showed good improvement in both groups, the decrease in the akinesia score was more pronounced in the STN group. In the STN group, the improvement of all motor symptoms was very close, or equal, to the best levodopa response. Thus the levodopa test was predictive of outcome. The improvement in off-drug period motor handicap allowed a decrease in the levodopa-equivalent dose only in the STN group (-56%). The voltage, frequency and pulse width used for chronic stimulation were lower in the STN group. In the on-drug phases there was a marked improvement in LID in the GPi group, as measured by the dyskinesias score during an acute levodopa test, whereas there was only a small decrease in the STN group (P < 0.05). However, in the long term, the reduction of levodopa dosage in the STN group led to an indirect reduction of LID similar to that in the GPi group during activities of everyday life. In conclusion, the overall results favour the neurosurgical treatment of Parkinson's disease by stimulating the STN rather than the GPi.

Adult↗
PubMed1996

Imaging of dopamine receptors with [123I]iodobenzamide single-photon emission-computed tomography in neuroleptic malignant syndrome.

With the tracer [123I]iodobenzamide ([123I]-IBZM), it is possible to image dopamine receptor occupancy with single-photon emission-computed tomography (SPECT). We report follow-up examinations with IBZM-SPECT in neuroleptic malignant syndrome (NMS) to display D2-receptor availability in the acute phase and during the course of remission. A 27-year-old man was admitted with severe akinesia, rigor, tachycardia, fever, and elevated creatine phosphokinase level (CK) after neuroleptic medication. NMS was diagnosed, and treatment was started with dantrolene, amantadine, and dopamine agonists. IBZM-SPECT examination was performed on days 6, 34, 90, 107, 131, and 201. In the acute state of NMS, there was no binding of IBZM to D2-receptors. SPECT reached almost normal values on day 131, but clinical examination still showed a mild parkinsonian syndrome. With SPECT, the D2-receptor occupancy in NMS could be successfully shown in correlation with extrapyramidal signs. IBZM-SPECT may therefore serve to monitor D2-receptor occupancy in patients at risk for NMS.

Adult↗
PubMed1996

Clinical neurophysiology of tremor.

The neurophysiological analysis of tremor has a long tradition. These attempts were directed to understand the mechanisms underlying tremor, on the one hand, and to develop tools to better diagnose the different types of tremor, on the other. Meanwhile, reasonable criteria are available to distinguish between centrally and peripherally mediated tremors. However, no generally accepted means exist to differentiate the different forms of central tremors. Frequency is a useful classifier for cerebellar tremor, rubral tremor, and orthostatic tremor. Although the highest amplitudes are found in Parkinson's disease, this parameter does not well distinguish between the different tremors. Waveform analysis of tremor is a promising tool to separate between the different tremors. Polymyography is pathognomonic for some rare forms of tremor. New approaches to classify tremors are based on positron emission tomography scanning, analysis of ballistic movement, and reflex testing. The means to separate myoclonias from tremors include EEG/EMG correlation techniques, long-latency reflexes, and polymyography. Provided these techniques are applied in the setting of careful clinical analysis of tremor syndromes, they may prove to be helpful in clinical practice.

Cerebellum↗
PubMed1994

"Apraxia of lid opening," a focal eyelid dystonia: clinical study of 32 patients.

We have seen 32 patients with "apraxia of lid opening" (ALO) in the following clinical settings: as an isolated condition (3 patients), idiopathic blepharospasm (BSP, 20 patients, including 4 familial cases), progressive supranuclear palsy (PSP, 7 patients), and dystonic parkinsonian syndrome (2 patients). Twenty-nine patients treated with botulinum toxin into the orbicularis oculi muscle were rated before and after treatment and 83% of the patients improved on a clinical scale. Best results were obtained with injections directed toward the junction of the preseptal and pretarsal parts of the palpebral orbicularis oculi. Several patients also improved on anticholinergic drugs. Besides medical treatment, lid crutches, in conjunction with botulinum toxin injections, were useful in some patients. ALO is not a true apraxia; it constitutes an eyelid dystonia as shown by its clinical and electrophysiological features as well as pharmacological reactions and is encountered in a clinical spectrum ranging from an isolated form to predominant BSP. It was an important cause of treatment failures in botulinum toxin-treated BSP but by modifying our injection strategy and by adding anticholinergic drugs and also lid crutches, we obtained a good functional benefit.

Adult↗
PubMed1993

Outcome of patients with aneurysmal and presumed aneurysmal bleeding. A hospital study based on 100 consecutive cases in a neurological clinic.

One hundred patients with spontaneous subarachnoid hemorrhage due to aneurysm or presumed aneurysm consecutively admitted to a neurological clinic and subjected to CCT during the first 72 hours were examined retrospectively. The outcome after two months as defined by the Glasgow Outcome Scale (GOS) was relatively good: 23% of the patients suffered management mortality (GOS I) (postoperative lethality 8%), 3% showed GOS-Grade II, 14% grade III, 17% grade IV, and 43% grade V. The extent of intracranial hemorrhage correlated well with the initial Hunt-Hess Grade which, in turn, had a strong influence on case fatality and the degree of disability. Lethal factors were: 1. massive subarachnoid hemorrhage together with a massive ventricular hemorrhage (p < 0.001), 2. massive subarachnoid hemorrhage together with an intracerebral hematoma > 20 ml (p < 0.05). Case fatality was lower when angiography was negative. In our study rebleeding (12%) and delayed cerebral ischemia (DCI) (18%) were less frequent and the lethality due to acute hydrocephalus (5%) and delayed cerebral ischemia (5%) was less pronounced than in comparable studies. The degree of disability (GOS) was directly related to the amount of intracranial blood, to the development of acute or chronic hydrocephalus, delayed cerebral ischemia and rebleeding. DCI occurred in 60% of patients with marked hydrocephalus. Rebleeding was more frequent in patients with acute hydrocephalus. Hydrocephalus, DCI, and rebleeding were associated with a poorer initial grade on the Hunt and Hess Scale.

Adult↗
PubMed1992

Changing pattern of brain hemorrhage during 12 years of computed axial tomography.

BACKGROUND AND PURPOSE: We examined whether the pattern of cerebral hemorrhage changed after the introduction of computed tomography. METHODS: Using a prospective data base we analyzed the case-fatality ratio, early mortality, and the incidences of hypertension and anticoagulant medication in 488 consecutive cases with supratentorial hemorrhage between 1978 and 1989. Blood pressure at admission of all patients for the years 1978-1979 and 1988-1989 and the Mathew and activities of daily living scores for the years 1978-1979, 1982-1983, and 1988-1989 were assessed retrospectively. RESULTS: The case-fatality ratio decreased from 49% in the period 1978-1981 to 31% in 1986-1989 (p = 0.006); early mortality (day 1-4) decreased from 28% to 12% (p = 0.0017). The incidence of hypertension decreased from 78% in the period 1978-1981 to 64% in 1986-1989 (p = 0.01). Systolic and diastolic blood pressure at admission sank (p = 0.09). The decrease of the case-fatality ratio correlated best with a less severe initial disturbance of consciousness (p less than 0.01) and with a higher Mathew score (p = 0.038). The activities of daily living score remained unchanged. CONCLUSIONS: The case-fatality ratio and early mortality decreased after the introduction of computed tomography. This was basically due to a decreased incidence of comatose and stuporous patients with severe neurological deficit paralleled by a decrease of mean systolic and diastolic blood pressure values at admission.

Aged↗
PubMed1992

[The reflex hammer].

When Erb began to study the knee jerk around 1870 he was able to use the percussion hammer for this purpose. Whereas percussion nowadays is performed with bare fingers, every physician carries a reflex hammer in his bag. Many varieties of reflex hammer have been developed. Their distribution today depends on their use by different schools. The origins and development of the most popular contemporary reflex hammers in English, French and German speaking countries are described.

Equipment Design↗
PubMed1992

[Communicating syringomyelia and syringobulbia after surgery of a spinal epidural tuberculoma].

In a 46 year old patient a syringomyelia and syringobulbia were diagnosed clinically 18 years after a transverse lesion of the cord and removal of an epidural spinal tuberculoma. Post-myelographic CT and NMR scans showed a communicating syringomyelia and syringobulbia. A flavectomy was performed and a syringopleural shunt implanted. The operation was successful by neuroradiological criteria. Clinically there was a worsening of the spastic gait during one-year follow up. Neuroradiological findings and etiology of the syrinx are discussed, and a causal relationship to the tuberculoma is proposed.

Brain Stem↗
PubMed1990

Age-related spontaneous intracerebral hematoma in a German community.

We investigated incidence, age distribution in relation to etiology, and localization of spontaneous intracerebral hematoma in 100 consecutive cases. Incidence in the total population of the Giessen area was estimated to be greater than 11/100,000 inhabitants/yr and increased with age. There was a trend toward higher incidence in males. Overall mortality was 27%, 22% of 58 patients aged less than 70 years and 33% of 42 patients aged greater than or equal to 70 years. Hypertensive putaminal hematoma showed the highest mortality rate (42%, 10 of 24 cases). Chronic alcoholism and anticoagulant medication influenced the mortality rate unfavourably. We found the following localizations and etiologies to have a specific relation with age: 1) lobar hematomas from vascular malformations, group aged less than 40 years; 2) hypertensive putaminal hematomas and hypertensive thalamic hematomas, group aged 40-69 years; and 3) lobar hematomas, group aged greater than or equal to 70 years. Alcoholism was an additional factor in 38% of the 13 middle-aged men with hypertensive putaminal hematomas. Fourteen cases of spontaneous intracerebral hematoma were possibly due to cerebral amyloid angiopathy. Six of these 14 patients had recurrent lobar hematomas, but only three of the six could be histologically investigated. In these three cases, cerebral amyloid angiopathy was proven.

Adult↗