Stn Gamma Knife Surgery In Patients With Severe Parkinson Disease With Contraindication For Dbs: About A Preliminary Series Of 3 Cases.

Jean Regis1, Witjas Tatiana2, Porcheron Denis2, Peragut Jean Claude2, Azulay Jean Philippe2

1Marseille, France 2Timone University Hospital, Marseille, France

Keywords: gamma knife, outcome, Parkinson's Disease, deep brain stimulation, tremor

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     Chronic STN stimulation is an established treatment for complicated PD. Bilateral subthalamotomy may induce significant and long-lasting results when DBS is not available. However, which alternative can be proposed for patients with surgical or medical contraindications for electrodes implantation? VIM Gamma Knife Surgery (GKS) is an effective therapy for treating disabling tremor. This technique encounters very few contraindications as it is done without craniotomy.
     We report here the case of three patients with severe PD who underwent unilateral STN Gamma Knife Surgery.
     Three PD patients with severe motor complications were assessed before surgery. Although, all of them had a good motor response to levodopa without emerging axial symptoms or cognitive impairment, STN DBS was contraindicated. Patient 1, a 53-year-old man had a severe diabetes mellitus with vasculopathy at the MRI and foot chronic infection. Patient 2, a woman aged of 68 years had severe ventricle enlargement. Patient 3, a 64-year-old man had diabetes, hypertension, and ventricle enlargement.
     A unilateral Gamma Knife subthalamotomy on the most affected side was proposed. Each patient gave his informed consent. Stereotactic MR was including HighT2 ventriculographic Axial imaging , a Coronal T2 sequence (SE 60/120) and a 3D T1 axial gadolinium enhanced sequence. STN targeting was achieved with Leksell Gamma unit relying on a single exposure through a 4mm collimator helmet. The GKS dose at the maximum was 110Grays.
     Unfortunately, patient 2 died of an aggressive gastric cancer nine months after the radiosurgical procedure. However, she reported motor improvement 3months after surgery. In patient 1 and 3 the follow up was X and Y months and they had an equivalent pattern of respons. At 3 months, they reported mild unilateral dyskinesia. At 6 and 12 months the motor improvement was of 51% for patient 1 and 58% for patient 3 without dyskinesia. The LEDD decrease was 45% for patient 1 and 35% for patient 3. Between 12 and 18 months, both patients experienced sudden severe akinesia that mimic hemiparesia. The MRI showed typical gamma knife induced ring-enhancing lesion within the STN associated with vasogenic edema that encompasses Substantia Nigra.. The symptoms resolved spontaneously in less than 2 months. At 3years after radiosurgery, patient 1 remains stable although axial symptoms emerge. Patient 3 has only a slight intermittent tremor without akinesia or rigidity after 2years.
     This is a retrospective study.
     Gamma Knife subthalamotomy may be an alternative treatment for severe PD patients with contraindication for DBS.
     Further follow up and larger series remain necessary for safety efficacy assessement of STN GKS in this specific population.


Project Roles:

J. Regis (), W. Tatiana (), P. Denis (), P. Claude (), A. Philippe ()