Gamma Knife surgery targeting the centromedian nucleus of the thalamus for the palliative management of thalamic pain: durable response in stroke-induced thalamic pain syndrome.

The authors report the neuroimaging features, treatment planning, and outcome in a case of radiosurgical thalamotomy targeting the centromedian nucleus (CMN) for stroke-induced thalamic pain. A 79-year-old man, with embolic occlusion of the left middle cerebral artery and large hemispheric infarction involving the thalamus, suffered a right hemiplegia and expressive aphasia. One year poststroke, severe right-sided facial, scalp, arm, and trunk pain developed and was exacerbated by any tactile contact. Medical treatment had failed. Medical illness, including mandatory anticoagulation therapy for atrial fibrillation, precluded surgical procedures. Minimally invasive radiosurgery was offered as an alternative. Magnetic resonance imaging and computed tomography were used to localize the left CMN. A single shot of 140 Gy was delivered to the 100% isodose line by using the 4-mm collimator helmet. The patient was evaluated at regular intervals. By 12 weeks posttreatment, he had significant improvements in pain control and his ability to tolerate physical contact during activities of daily living. Magnetic resonance imaging demonstrated baseline encephalomalacia from his prior stroke, and signal changes in the left CMN consistent with gamma irradiation-based thalamotomy. Currently, nearly 7 years after radiosurgery, he continues to enjoy a marked reduction in pain without the need of analgesic medications. Thalamic pain syndrome is generally refractory to conventional treatment. Neurosurgical interventions provide modest benefit and carry associated risks of invasive surgery and anesthesia. The CMN is readily localized with neuroimaging and is an approximate target to reduce the suffering aspect of pain. In this case, radiosurgery was a safe and effective treatment, providing durable symptom control and improved quality of life.

Gamma knife subthalamotomy for Parkinson disease: the subthalamic nucleus as a new radiosurgical target. Case report.

The authors present the neuroimaging, treatment planning, and radiosurgical technique for the first reported case of unilateral radiosurgical subthalamotomy, which was performed to control motor symptoms associated with advanced Parkinson disease (PD) in a patient who had undergone previous contralateral radiofrequency (RF) pallidotomy. A 73-year-old woman with end-stage PD had undergone RF pallidotomy of the right globus pallidus with resolution of symptoms. Two years following this procedure, due to the natural progression of her disease, she suffered recurrent motor fluctuations, dyskinesia, and worsening bradykinesia of the right side. Her Parkinson's Disease Disability Rating (PDDR) score was 28. Computerized tomography and magnetic resonance (MR) imaging were used to localize the left subthalamic nucleus (STN). The patient underwent gamma knife radiosurgery-a single shot of 120 Gy was administered using the 4-mm collimator helmet. The patient was evaluated up to 42 months after the procedure. The dyskinesia became minimal. Right-sided motor control improved as did her balance. At 3 months after treatment MR imaging demonstrated the radiosurgical lesion in the left STN. At 3.5 years postradiosurgery, she experienced minimal focal (oral) dyskinesia, no bradykinesia or rigidity, and her PDDR score was 11. Radiosurgery of the STN in this case was safe and effective. The STN is a readily localized anatomical target with neuroimaging. Radiosurgery avoids the risks of open procedures.