Patients with HHT have a high risk of harboring a CVM, especially in the presence of a pulmonary AVM. These CVMs are mostly low-grade AVMs (Spetzler-Martin Grade I or II), are frequently multiple, and have a lower risk of bleeding than that associated with sporadic AVMs. Female patients are more often affected than male patients. The inherent low sensitivity of DS angiography screening for CVMs may yield false negative results.
SummaryThe retrospective results of external lumbar drainage in 7 adult patients with severe closed head injury and intracranial pressure (ICP) refractory to aggressive management strategies are presented. All patients had Glasgow Coma Scale (GCS) scores of 8 or less within 24 hours after admission and were treated by a staircase protocol including sedation, ventricular drainage, hyperventilation and mannitol. In three cases barbiturate drugs and an artificially induced hypothermia were used. Four patients required surgical evacuation of mass lesions. Three patients made a good functional recovery, 2 were severely disabled and 2 patients died. In none of the patients clinical signs of cerebral herniation occurred. We recommend additional external lumbar drainage in adults with severe head injury unresponsive to agressive ICP control with open basilar cisterns and absent focal mass lesions on computerized-tomography scan before drainage.
ObjectivesThe presence of intracranial lesions or epilepsy may lead to functional reorganization and hemispheric lateralization. We applied a clinical magnetoencephalography (MEG) protocol for the localization of the contralateral and ipsilateral S1 and M1 of the foot and hand in patients with non-lesional epilepsy, stroke, developmental brain injury, traumatic brain injury and brain tumors. We investigated whether differences in activation patterns could be related to underlying pathology.MethodsUsing dipole fitting, we localized the sources underlying sensory and motor evoked magnetic fields (SEFs and MEFs) of both hands and feet following unilateral stimulation of the median nerve (MN) and posterior tibial nerve (PTN) in 325 consecutive patients. The primary motor cortex was localized using beamforming following a self-paced repetitive motor task for each hand and foot.ResultsThe success rate for motor and sensory localization for the feet was significantly lower than for the hands (motor_hand 94.6% versus motor_feet 81.8%, p < 0.001; sensory_hand 95.3% versus sensory_feet 76.0%, p < 0.001). MN and PTN stimulation activated 86.6% in the contralateral S1, with ipsilateral activation < 0.5%. Motor cortex activation localized contralaterally in 76.1% (5.2% ipsilateral, 7.6% bilateral and 11.1% failures) of all motor MEG recordings. The ipsilateral motor responses were found in 43 (14%) out of 308 patients with motor recordings (range: 8.3–50%, depending on the underlying pathology), and had a higher occurrence in the foot than in the hand (motor_foot 44.8% versus motor_hand 29.6%, p = 0.031). Ipsilateral motor responses tended to be more frequent in patients with a history of stroke, traumatic brain injury (TBI) or developmental brain lesions (p = 0.063).ConclusionsMEG localization of sensorimotor cortex activation was more successful for the hand compared to the foot. In patients with neural lesions, there were signs of brain reorganization as measured by more frequent ipsilateral motor cortical activation of the foot in addition to the traditional sensory and motor activation patterns in the contralateral hemisphere. The presence of ipsilateral neural reorganization, especially around the foot motor area, suggests that careful mapping of the hand and foot in both contralateral and ipsilateral hemispheres prior to surgery might minimize postoperative deficits.
Vibratory inhibition, the homonymous recovery curve and the ratio of the maximal H-reflex to direct muscle potential (H/M ratio) of the soleus H-reflex were assessed in 10 patients with leg dystonia and in six patients with arm or neck dystonia. The results were compared with those obtained in 48 healthy control subjects. H-reflex variables most helpful for the discrimination of patients and healthy subjects were identified. In patients with leg dystonia, vibratory inhibition was less marked than in control subjects, whereas late facilitation of the recovery curve was increased. In patients with leg dystonia, area values of test reflexes in the late facilitatory phase of the recovery curve exceeded peak-peak values, in contrast to findings in control subjects. This finding may be attributable to less synchronization of enhanced test reflexes in dystonia than in the control condition. In differentiating patients with leg dystonia from control subjects, a combination of parameters of vibratory inhibition and the late facilitatory phase of the recovery curve appeared most useful. In patients with arm or neck dystonia and in the unaffected legs of hemidystonic patients, soleus H-reflex test results were in the normal range. Abnormalities in the results of the soleus H-reflex tests we used appear to be related to the presence of clinical signs in the extremity under examination and not to the severity of features.
To study the topographical organization of mu and beta band event-related desynchronization (ERD) associated with voluntary hand and foot movements, we used magnetoencephalographic (MEG) recordings from 19 patients with perirolandic lesions. Synthetic aperture magnetometry (SAM) was used to detect and localize changes in the mu (7 - 11 Hz) and beta (13 - 30 Hz) frequency bands associated with repetitive movements of the hand and foot and overlaid on individual coregistered magnetic resonance (MR) images. Hand movements showed homotopic and contralateral ERD at the sensorimotor (S/M) cortex in the majority of cases for mu and to a lesser extent for beta rhythms. Foot movements showed an increased heterotopic distribution with bilateral and ipsilateral ERD compared to hand movements. No systematic topographical segregation between mu and beta ERD could be observed. In patients with perirolandic lesions, the mu and beta band spatial characteristics associated with hand movements retain the expected functional-anatomical boundaries to a large extent. Foot movements have altered patterns of mu and beta band ERD, which may give more insight into the differential functional role of oscillatory activity in different voluntary movements.
Patients using 4-FA are at risk for life-threatening health problems, including intracranial haemorrhage. Additional brain imaging should be considered in 4-FA-intoxicated patients, not only in the presence of neurological deficits, but also in the case of severe headache.
Human cortical pyramidal neurons are large, have extensive dendritic trees, and yet have surprisingly fast input-output properties: rapid subthreshold synaptic membrane potential changes are reliably encoded in timing of action potentials (APs). Here, we tested whether biophysical properties of voltage-gated sodium (Na+) and potassium (K+) currents in human pyramidal neurons can explain their fast input-output properties. Human Na+ and K+ currents had depolarized voltage-dependence, slower inactivation and exhibited a faster recovery from inactivation than their mouse counterparts. Computational modeling showed that despite lower Na+ channel densities in human neurons, the biophysical properties of Na+ channels resulted in higher channel availability and contributed to fast AP kinetics stability. Finally, human Na+ channel properties also resulted in a larger dynamic range for encoding of subthreshold membrane potential changes. Thus, biophysical adaptations of voltage-gated Na+ and K+ channels enable fast input-output properties of large human pyramidal neurons.
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