Complications of Gamma Knife Surgery for Parkinson Disease
February 1, 2002
Complications of Gamma Knife Surgery for Parkinson Disease
Abstract & Commentary
Source: Okun MS, et al. Complications of gamma knife surgery for Parkinson disease. Arch Neurol. 2001;58: 1995-2002.
Neurosurgery in the past 50 years has developed several intracranial procedures involving the basal ganglia and thalamus in hopes to ameliorate the crippling factors of progressive, late-stage Parkinson disease (PD). One relatively new, nonsurgical approach has consisted of using the noninvasive, radiosurgical gamma knife (GK). The GK depends on first quality, cerebral MRIs to define by cubic millimeters the fine target structures that inhabit the particular patient’s thalamus and basal ganglia. From these mappings, the GK earlier directed an 8- or 4-mm collimater to control the radiation target size. A 4-mm diameter collimator has been designed to destroy just a 64 cu mm spot in the calculated thalamic or basal ganglia target. Two difficulties can occur from such steps, however. One can come immediately or the other can evolve from 1-12 months following the surgery. Unfortunately, Okun and colleagues encountered serious complications in 8 patients who underwent the GK. These all suffered distressing outcomes which appeared as follows: 1) body numbness, pseudobulbar, and laughter (1 mo); 2) hypophonia + aphasia (5 mos); 3) dysarthria, aspiration, and death (4 mos.); 4) hand weak, dysarthria (4 mos.); 5) hemiparesis (10 mos.); 6) visual field loss (3 mos, permanent); 7) hemiparesis, dysarthria (months or more).
Problems included: a) the GK lesions in the whole cohort averaged 1.5 ± 0 mm off their targeted goals; b) lesions involving functional structures adjacent to the intended target seriously affected every one of the 8 patients; and c) at best, no patient was improved more than 4 months and most were improved by a matter of weeks or none at all.
Commentary
The unfortunate outcomes of this group of PD patients all come from a high-quality university medical center with excellent clinical and fundamental neurological programs. GK treatment may be favorable for cerebral neoplastic therapy, but the spatial geography of critically different functions that originate in the thalamus or basal ganglia appear too small to use isolate functional GK therapy. —Fred Plum, MD. Dr. Plum, University Professor, Weill Medical College, and Attending Neurologist, New York Presbyterian Hospital, is Editor of Neurology Alert.
Additional Reading
1. Lang AE. Ann Neurol. 2000;47 (suppl 1):S193-S202.
2. Friedman JH, et al. Ann Neurol. 1996;38:535-538.
3. Duma CM, Jacques D, Kopyov OV. Neurosurg Clin N Am. 1999;10:379-389.
4. Jankovic J. Arch Neurol. 2001;58:1970-1972.
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