Gamma knife thalamotomy for disabling tremor: a blinded evaluation.
ABSTRACT Gamma knife thalamotomy (GKT) has been used as a therapeutic option for patients with disabling tremor refractory to medications. Impressive improvement of tremor has been reported in the neurosurgical literature, but the reliability of such data has been questioned.
To prospectively evaluate clinical outcomes after GKT for disabling tremor with blinded assessments.
Prospective study with blinded independent neurologic evaluations.
Consecutive patients who underwent unilateral GKT for essential tremor and Parkinson disease tremor at our center. These patients were unwilling or deemed unsuitable candidates for deep brain stimulation or other surgical procedures.
Unilateral GKT and regular follow-up evaluations for up to 30 months, with blinded video evaluations by a movement disorders neurologist.
Clinical outcomes, as measured by the Fahn-Tolosa-Marin Tremor Rating Scale and activities of daily living scores, and incidence of adverse events.
From September 1, 2006, to November 30, 2008, 18 patients underwent unilateral GKT for essential tremor and Parkinson disease tremor at our center. Videos for 14 patients (11 with essential tremor, 3 with Parkinson disease tremor) with at least 6 months' postoperative follow-up were available for analysis (mean [SD] follow-up duration, 19.2 [7.3] months; range, 7-30 months). The Fahn-Tolosa-Marin Tremor Rating Scale activities of daily living scores improved significantly after GKT (P = .03; median and mean change scores, 2.5 and 2.7 points, respectively [range of scale was 0-27]), but there was no significant improvement in other Fahn-Tolosa-Marin Tremor Rating Scale items (P = .53 for resting tremor, P = .24 for postural tremor, P = .62 for action tremor, P = .40 for drawing, P > .99 for pouring water, P = .89 for head tremor). Handwriting and Unified Parkinson's Disease Rating Scale activities of daily living scores tended to improve (P = .07 and .11, respectively). Three patients developed delayed neurologic adverse events.
Overall, we found that GKT provided only modest antitremor efficacy. Of the 2 patients with essential tremor who experienced marked improvement in tremor, 1 subsequently experienced a serious adverse event. Further prospective studies with careful neurologic evaluation of outcomes are necessary before GKT can be recommended for disabling tremor on a routine clinical basis.
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ABSTRACT: Medication is the predominant method for the management of patients with movement disorders. However, there is a fraction of patients who experience limited relief from pharmaceuticals or experience bothersome side-effects of the drugs. Deep brain stimulation (DBS) and surgical lesioning of the thalamus and basal ganglia are respected neurosurgical procedures, with valued success rates and a very low incidence of complications. Despite these positive outcomes, DBS and surgical lesioning procedures are contraindicated for some patients. Stereotactic radiosurgery with the Gamma Knife (GK) has been used as a lesioning technique for patients seeking a non-invasive treatment alternative and for medication-intolerable patients, who are unable to undergo DBS or lesioning due to comorbid medical conditions. Tremors of various etiologies are treated using GK thalamotomy, which targets the ventralis intermedius nucleus. GK thalamotomy produces favorable outcomes when treating tremors, with success rates ranging from 80-100%. In contrast, GK pallidotomy targets the internal globus pallidus, and is used in treating bradykinesia, rigidity, and dyskinesia. Although radiosurgery has proven beneficial for tremors, radiosurgical pallidotomy for bradykinesia, rigidity, and dyskinesia remains questionable, with mixed success rates in the literature that ranges from 0-87%. We suggest that GK thalamotomy be offered along with other neurosurgical approaches as a feasible treatment option to patients who prefer the non-invasive nature of radiosurgery and to those who are unqualified candidates for the neurosurgical alternatives. Also, we advise that patients with bradykinesia, rigidity, and dyskinesia be educated about the variability in the literature pertaining to GK pallidotomy before proceeding with treatment.World Journal of Surgical Oncology 01/2010; 8:61. · 1.09 Impact Factor
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ABSTRACT: Essential tremor is one of the most common movement disorders in the world. Although millions of people worldwide are affected by ET, only one medication, propranolol, is approved by the United States Food and Drug Administration to treat it. None of the medications currently used as ET therapy were developed specifically for this purpose, and select antihypertensive and antiepileptic medications remain at the forefront of ET therapy. Propranolol and primidone are considered "effective" agents that treat ET; topiramate, atenolol, and alprazolam are "probably effective", and nimodipine, nadolol, and clonazepam are "possibly effective". Medications that probably do not adequately treat ET include levetiracetam and pregabalin. Gabapentin appears to improve ET when used as monotherapy, but not when used as adjunct therapy. Sotalol has been found to be "probably effective" in treating ET in previous reviews, but it may be associated with arrhythmias and should not be routinely recommended. Botulinum toxin A may reduce limb tremor, but may cause dose dependent weakness. Deep brain stimulation (DBS) of the VIM is used as an alternative to pharmacological therapy of ET in patients who fail to adequately respond to medical therapy. The magnitude of effect from DBS is greater than from medical management, but more severe side effects are possible with surgery. Future treatment options for ET will depend on valid animal models, and a better understanding of its pathophysiology.Current Treatment Options in Neurology 07/2013; · 1.94 Impact Factor
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ABSTRACT: Initially designed for the treatment of functional brain targets, stereotactic radiosurgery (SRS) has achieved an important role in the management of a wide range of neurosurgical pathologies. The interest in the application of the technique for the treatment of pain, and psychiatric and movement disorders has returned in the beginning of the 1990s, stimulated by the advances in neuroimaging, computerized dosimetry, treatment planning software systems, and the outstanding results of radiosurgery in other brain diseases. Since SRS is a neuroimaging-guided procedure, without the possibility of neurophysiological confirmation of the target, deep brain stimulation (DBS) and radiofrequency procedures are considered the best treatment options for movement-related disorders. Therefore, SRS is an option for patients who are not suitable for an open neurosurgical procedure. SRS thalamotomy provided results in tremor control, comparable to radiofrequency and DBS. The occurrence of unpredictable larger lesions than expected with permanent neurological deficits is a limitation of the procedure. Improvements in SRS technique with dose reduction, use of a single isocenter, and smaller collimators were made to reduce the incidence of this serious complication. Pallidotomies performed with radiosurgery did not achieve the same good results. Even though the development of DBS has supplanted lesioning as the first alternative in movement disorder surgery; SRS might still be the only treatment option for selected patients.Surgical neurology international. 01/2012; 3(Suppl 1):S10-6.