Combining focused ultrasound (FUS) with real time MRI guidance and monitoring enables a new non-invasive treatment of brain disorders. In this technique multisource ultrasound waves are focused at a single point raising the temperature gradually until ablation occurs. Lesions as small as 2-4 mm can be made, without impact on surrounding tissue or remote brain tissue.
Our aim was to assess MR guided focused ultrasound (MRgFUS) as a new non-invasive surgical tool for treating essential and parkinsonian tremor by thalamotomy of the ventral-intermediate nucleus.
OBJECTIVE Thalamotomy of the ventral intermediate nucleus (VIM) is effective in alleviating medication-resistant tremor in patients with essential tremor (ET) and Parkinson's disease (PD). MR-guided focused ultrasound (MRgFUS) is an innovative technology that enables noninvasive thalamotomy via thermal ablation. METHODS Patients with severe medication-resistant tremor underwent unilateral VIM thalamotomy using MRgFUS. Effects on tremor were evaluated using the Clinical Rating Scale for Tremor (CRST) in patients with ET and by the motor part of the Unified Parkinson's Disease Rating Scale (UPDRS) in patients with PD and ET-PD (defined as patients with ET who developed PD many years later). Quality of life in ET was measured by the Quality of Life in Essential Tremor (QUEST) questionnaire and in PD by the PD Questionnaire (PDQ-39). RESULTS Thirty patients underwent MRgFUS, including 18 with ET, 9 with PD, and 3 with ET-PD. The mean age of the study population was 68.9 ± 8.3 years (range 46-87 years) with a mean disease duration of 12.1 ± 8.9 years (range 2-30 years). MRgFUS created a lesion at the planned target in all patients, resulting in cessation of tremor in the treated hand immediately following treatment. At 1 month posttreatment, the mean CRST score of the patients with ET decreased from 40.7 ± 11.6 to 9.3 ± 7.1 (p < 0.001) and was 8.2 ± 5.0 six months after treatment (p < 0.001, compared with baseline). Average QUEST scores decreased from 44.8 ± 12.9 to 13.1 ± 13.2 (p < 0.001) and was 12.3 ± 7.2 six months after treatment (p < 0.001). In patients with PD, the mean score of the motor part of the UPDRS decreased from 24.9 ± 8.0 to 16.4 ± 11.1 (p = 0.042) at 1 month and was 13.4 ± 9.2 six months after treatment (p = 0.009, compared with baseline). The mean PDQ-39 score decreased from 38.6 ± 16.8 to 26.1 ± 7.2 (p = 0.036) and was 20.6 ± 8.8 six months after treatment (p = 0.008). During follow-up of 6-24 months (mean 11.5 ± 7.2 months, median 12.0 months), tremor reappeared in 6 of the patients (2 with ET, 2 with PD, and 2 with ET-PD), to a lesser degree than before the procedure in 5. Adverse events that transiently occurred during sonication included headache (n = 11), short-lasting vertigo (n = 14) and dizziness (n = 4), nausea (n = 3), burning scalp sensation (n = 3), vomiting (n = 2) and lip paresthesia (n = 2). Adverse events that lasted after the procedure included gait ataxia (n = 5), unsteady feeling (n = 4), taste disturbances (n = 4), asthenia (n = 4), and hand ataxia (n = 3). No adverse event lasted beyond 3 months. Patients underwent on average 21.0 ± 6.9 sonications (range 14-45 sonications) with an average maximal sonication time of 16.0 ± 3.0 seconds (range 13-24 seconds). The mean maximal energy reached was 12,500 ± 4274 J (range 5850-23,040 J) with a mean maximal temperature of 56.5° ± 2.2°C (range 55°-60°C). CONCLUSIONS MRgFUS VIM thalamotomy to relieve medication-resistant tremor was safe and effective in patients with ET, PD, and ET-PD. Current results emphasize the superior adverse events profile of MRgFUS over other surgical approaches for treating tremor with similar efficacy. Large randomized studies are needed to assess prolonged efficacy and safety.
Introduction – The objective of this study was to describe facial myokymia in experimental animals accompanying kainic acid affects on facial motor neurons. Material & methods – Anesthetized cats were injected with kainic acid into the pons adjacent to the facial nucleus. Facial movements appeared shortly after the injections and facial electromyographic potentials were recorded. Cats were killed up to 4 weeks later, the brainstems were processed histologically, and the number of neurons in the facial nucleus counted. Results – Cats receiving injection of kainic acid adjacent to facial nucleus all developed spontaneous writhing movements of the face ipsilateral to the injection site, clinically resembling facial myokymia in humans. Transient facial paresis, lasting several weeks, appeared in some of the cats. Facial myokymia occurred independent of histological evidence of neuronal loss in facial nucleus, whereas facial paresis occurred in all but one of the animals with significant neuronal loss in the facial nucleus. Placing a needle into the superior olive without injecting kainic acid or injections of kainic acid into cochlear nucleus was not accompanied by facial myokymia or subsequent facial paresis. Conclusion – Facial movements in cats similar to myokymia in humans accompanies kainic acid injections adjacent to the nucleus of the facial nerve.
This paper models, analyzes and optimizes a novel swimming method for a swimming micro robot. The propulsion is achieved by creating a traveling wave in an elastic tail made of piezo-electric actuators. The novel swimming method was analyzed analytically by solving the coupled elastic/fluidic problem. The parameters that influence swimming were identified and optimized. It was found that under the extreme size limitations a tail manufactured by current MEMS technology is able to swim at the order of several cm/sec in water
Objective The purpose of this study was to separate the composite components of the auditory 40 Hz steady-state potentials (40 Hz SSP), by differentially augmenting them with filtering at different low passes, and to compare them with their counterparts in the transient-evoked auditory middle-latency evoked potentials (AMEP). Methods Transient-evoked AMEP to 3.3/sec clicks and 40 Hz SSP to 40/sec clicks were recorded from 18 subjects using three orthogonally positioned electrode pairs. Each type of potentials was filtered with a 100 Hz and with a 50 Hz low pass. Equivalent dipoles of components were estimated using Three-channel Lissajous’ Trajectories and compared between filter settings (50 and 100 Hz low pass) and between the transient-evoked and the steady-state potentials. Results With a band pass of 3 to 100 each period of the 40 Hz SSP consisted of a brain stem (V) and four cortical (P0, Na, Pa1, Pa2, and Nb) components. The lower-frequency components of the 40-Hz response corresponded in latency and equivalent dipole orientation to the later transient-evoked cortical AMEP components, whereas the higher-frequency components corresponded to the earlier, brain stem and primary cortical components of transient-evoked AMEP. Band-pass filtering at 3 to 50 Hz resulted in fewer components, as early brain stem and primary cortical components diminished. Conclusions A band pass of 3 to 100 Hz for recording the 40 Hz SSP results in a composite waveform comprising of distinct brain stem and cortical generators with different orientations of their equivalent dipoles. The relative contributions of the multiple constituents are affected by the acquisition filter low pass: brain stem and primary cortical generators mostly contribute the high frequencies and later cortical contributions dominate the lower frequencies.
Four cases of cystic meningiomas were found among 194 meningiomas diagnosed by computed tomography (CT) and operated on during a 7 year period, an incidence of 2%. The cysts were in all cases peritumoral. The cyst's wall was the brain itself, and the ependymal ventricular wall was part of their medial boundary. They contained xanthochromic fluid with a high protein content. Three meningiomas were parasagittal and one was adjacent to the pteryon and the external part of the sphenoid ridge. The mural nodules were in 2 cases apparent single nodes although in one it was part of multiple distant and regional growths, in another the tumour was built by the aggregation of 2 nodes, the remaining case was an "en plaque" meningioma. All were definitely attached to the dura. Histological pattern was different in every case. Those parasagittal were: one pure meningotheliomatous, one mixed meningotheliomatous with pseudo psammomatous and lipoblastic sections and one highly vascular angioblastic; the pteryonal case was psammomatous and microcystic. CT diagnosis is difficult because glial, metastatic and other tumours may look cystic and resemble cystic meningiomas. Nevertheless in 3 cases the correct diagnosis was suspected preoperatively because the solid portion of the tumour showed intense and homogeneous contrast enhancement with a sharp edge and was located adjacent to the dura. On the other hand in the remaining case, the parasagittal solid tumour was not readily apparent on CT (the "en plaque", case), and the tentative preoperative diagnosis was of an epidermoid tumour. At operation on the contrary the macroscopic aspect was typical of meningioma and the histological peroperative frozen sections confirmed the diagnosis with ease in all cases. In the light of the aforesaid findings the authors conclude that every patient with a cystic tumour, no matter the tentative preoperative diagnosis is, should be given the benefit of surgical intervention.
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