Reorganization in the cutaneous core of the human thalamic principal somatic sensory nucleus (Ventral caudal) in patients with dystonia.
(17/1495)
A wide range of observations suggest that sensory inputs play a significant role in dystonia. For example, the map of the hand representation in the primary sensory cortex (area 3b) is altered in monkeys with dystonia-like movements resulting from overtraining in a gripping task. We investigated whether similar reorganization occurs in the somatic sensory thalamus of patients with dystonia (dystonia patients). We studied recordings of neuronal activity and microstimulation-evoked responses from the cutaneous core of the human principal somatic sensory nucleus (ventral caudal, Vc) of 11 dystonia patients who underwent stereotactic thalamotomy. Fifteen patients with essential tremor who underwent similar procedures were used as controls. The cutaneous core of Vc was defined as the part of the cellular thalamic region where the majority of cells had receptive fields (RFs) to innocuous cutaneous stimuli. The proportion of RFs including multiple parts of the body was greater in dystonia patients (29%) than in patients with essential tremor (11%). Similarly, the percentage of projected fields (PFs) including multiple body parts was higher in dystonia patients (71%) than in patients with essential tremor (41%). A match at a thalamic site was said to occur if the RF and PF at that site included a body part in common. Such matches were significantly less prevalent in dystonia patients (33%) than in patients with essential tremor (58%). The average length of the trajectory where the PF included a consistent, cutaneous RF was significantly longer in patients with dystonia than in control patients with essential tremor. The findings of sensory reorganization in Vc thalamus are congruent with those reported in the somatic sensory cortex of monkeys with dystonia-like movements resulting from overtraining in a gripping task. (+info)
Pre-operative planning and intra-operative guidance in modern neurosurgery: a review of 300 cases.
(18/1495)
Operative neurosurgery has recently entered an exciting era of image guided surgery or neuronavigation and application of this novel technology is beginning to have a significant impact in many ways in a variety of intracranial procedures. In order to fully assess the advantages of image guided techniques over conventional planning and surgery in selected cases, detailed prospective evaluation has been carried out during the advanced development of an optically tracked neuronavigation system. Over a 2-year period, 300 operative neurosurgical procedures have been performed with the assistance of interactive image guidance, as well as the development of new software applications and hardware tools. A broad range of intracranial neurosurgical procedures were seen to benefit from image guidance, including 163 craniotomies, 53 interactive stereotactic biopsies, 7 tracked neuroendoscopies and 37 complex skull base procedures. The most common pathological diagnoses were cerebral glioma in 98 cases, meningioma in 64 and metastasis in 23. Detailed analysis of a battery of postoperative questions revealed benefits in operative planning, appreciation of anatomy, lesion location, safety of surgery and greatly enhanced surgical confidence. The authors believe that image guided surgical technology, with new developments such as those described, has a significant role to play in contemporary neurosurgery and its widespread adoption in practice will be realised in the near future. (+info)
Aseptic meningitis after posterior fossa surgery treated by pseudomeningocele closure.
(19/1495)
Aseptic meningitis is a recognised complication after posterior fossa surgery. It is often self limiting but occasionally runs a protracted course requiring repeated CSF examination to exclude infection, and treatment with systemic steroids. A patient is described with aseptic meningitis after posterior fossa surgery who underwent posterior fossa re-exploration nearly 3 years after the initial operation. This disclosed a pseudomeningocele, which was closed. The patient remains symptom free almost 2 years after closure. In this case of chronic aseptic meningitis after posterior fossa surgery, closure of the pseudomeningocele found at exploratory surgery led to resolution of the symptoms. (+info)
Surgical treatments for Parkinson's disease.
(20/1495)
OBJECTIVE: This article reviews surgical treatments for Parkinson's disease, emphasizing aspects pertinent to family physicians: rationale for and description of surgeries, patient selection issues, and outcome expectations. QUALITY OF EVIDENCE: No published series describes long-term follow up of a randomized controlled study of any surgery for Parkinson's disease. Some reports, however, describe thorough but brief follow up of functioning in small numbers of patients following surgery. MEDLINE articles were identified using Parkinson's disease, surgery, pallidotomy, thalamotomy, stimulation, grafting, and transplantation as search words. Articles chosen for this paper described patients with systematic follow up using accepted validated rating scales. MAIN MESSAGE: Reported series show impressive improvements to patients undergoing lesioning, stimulation, and grafting surgery for Parkinson's disease. These patients are typically severely disabled but highly selected, and follow up is brief. Stereotactic lesioning (pallidotomy and thalamotomy), deep brain stimulation (thalamic, and elsewhere) and grafting (striatal) can be performed safely, but results vary greatly among centres. CONCLUSIONS: Certain Parkinson's disease patients might benefit from surgery. Ideal candidates for pallidotomy experience motor fluctuations with disabling levodopa-induced dyskinesias. Tremors resistant to antiparkinsonian medications sometimes respond to thalamotomy or thalamic stimulation. Other parkinsonian syndromes, dementias, and difficulties with gait and balance respond poorly to unilateral pallidotomy. Bilateral deep brain stimulation procedures could benefit "midline" dysfunction. (+info)
Visualization of the motor activation area using SPECT in neurosurgical patients with lesions near the central sulcus.
(21/1495)
The purpose of this study was to visualize the motor area related to finger movement and a fist-making task using SPECT in patients with lesions near the central sulcus. METHODS: Eleven patients (9 with a brain tumor, 1 with cerebral infarction, and 1 with an arteriovenous malformation) were investigated. The first intravenous injection of 99mTc-ethyl cysteinate dimer (ECD) for the motor activation SPECT images was administered 2 min after completion of the fist-making task with the hand contralateral to the brain lesion. The movement was stopped 2 min after injection, and activation SPECT was performed. After the scan, the second dose of 99mTc-ECD was injected into resting patients, and a second set of SPECT images was acquired. The first set of images was subtracted from the second set to obtain control images. Regions of interest were set bilaterally on the sensorimotor hand area; the supplementary motor area; the frontal, temporal, and occipital lobes; and the cerebellar hemispheres. The results of activation SPECT were expressed as positive or negative for a high-count area, and the regional percentage change for activation images relative to resting images was calculated. RESULTS: Visual assessment of activation images was positive in 9 patients for the sensorimotor hand area and 7 patients for the supplementary motor area. The regional percentage change between activation and resting images for the high-count areas was 19.7% for the sensorimotor hand area and 18.2% for the supplementary motor area. Both values were significantly higher than those for other areas (P<0.05). CONCLUSION: Motor activation SPECT using a 99mTc-ECD split-dose method is easy to perform and may be helpful for presurgical visualization and identification of the sensorimotor hand area or the supplementary motor area. (+info)
Far lateral approach for foramen magnum lesions.
(22/1495)
Twelve patients with lesions in the anterior or anterolateral regions of foramen magnum were treated through the far lateral approach. The patients presented with neck pain, dysesthesia, quadriparesis, numbness, respiratory distress, and spastic contractures. Most lesions were meningiomas and neurofibromas, with one patient each with a posterior inferior cerebellar artery aneurysm, neurenteric cyst, and chordoma. All mass lesions were excised totally and the aneurysm was clipped. Three patients had severe respiratory problems preoperatively and two of them died. The other patients made a satisfactory neurological recovery. It was not found necessary to resect the condyle or mobilize the vertebral artery in any of the patients. (+info)
Effect of low and high frequency thalamic stimulation on sleep in patients with Parkinson's disease and essential tremor.
(23/1495)
Continuous high frequency stimulation of the ventral intermediate nucleus of the thalamus (Vim), delivered through surgically implanted quadripolar electrodes, alleviates tremor in Parkinson's disease (PD) and essential tremor (ET). The Vim is adjacent to the thalamic reticular nuclei, where sleep spindles originate according to animal models. In order to determine whether Vim stimulation affects sleep spindles, six patients (4 PD, 2 ET), aged 60-69 years, were recorded on a control night and a stimulation night (130 Hz, 2-3 V; right stimulation in five patients and bilateral stimulation in one patient). Stimulation did not modify sleep quality or architecture. Sleep spindles were present and symmetrical in five out of six patients under stimulation. However, in one patient with a sustained 'thalamotomy-like effect' that abolished tremor, spindles were asymmetrical even without stimulation. In each patient, spindle density was similar on both nights (mean+/- SEM: 2.25+/-0. 61 spindles per min of stage 2 sleep vs. 1.84+/-0.31). In an attempt to promote sleep two different patterns of stimulation were applied in the region of ventrooralis posterior and reticularis nuclei in five patients in the awake state. Continuous low frequency stimulation (5 Hz, 0.1 V), and repeated trains of 15 Hz for 1 s every 15 s mimicking the pattern of physiological spindles, each failed to induce sleep or cortical synchronization. We conclude that Vim stimulation, unlike thalamotomy, selectively reduces tremor without altering sleep or sleep spindles. Our results also suggest that low frequency stimulation applied in the region of the reticular nuclei does not induce sleep. (+info)
Behaviour of near-infrared light in the adult human head: implications for clinical near-infrared spectroscopy.
(24/1495)
To test theoretical assumptions supporting the use of near-infrared spectroscopy (NIRS) in clinical practice, we examined the behaviour of NIR light transmission and attenuation in the human head. Sterile probes for emitting and detecting NIR light at a fixed separation of 40 mm were placed in turn on intact skin, skull, dura and cerebral cortex of 10 patients undergoing elective neurosurgery. In the first five patients, the detecting probe was moved through successive extracerebral layers with the emitter on the skin surface. In the second five patients, the process was reversed, with the emitting probe moved and the detector in the same place on the scalp. NIR intensity was measured at each tissue interface and compared with the intensity measured at the skin surface with all layers intact. Removal of bone and dura from the light path caused a significant reduction in detected intensity. The largest mean reduction in light intensity was a 14-fold decrease with removal of bone (unadjusted P < 0.0001; paired t test). The assumptions that extracerebral tissues contribute little to attenuation of NIR light in the adult head and that most of this attenuation occurs superficially in the scalp are drawn into question by this study. We postulate that the skull and/or its interface with other layers may act as an optical 'channel', distorting the behaviour of NIR light in the human head. (+info)