PMID: 9688111 | Gamma knife radiosurgery in movement disorders

[janet paterson <janet313@xxxxxxxxxxx>]

Gamma knife radiosurgery as a lesioning technique in movement disorder surgery.

OBJECT: To increase knowledge of the safety and efficacy of the use of gamma 
knife radiosurgery in patients with movement disorders, the authors describe 
their own experience in this field and include blinded independent assessments 
of their results.

METHODS: Fifty-five patients underwent radiosurgical placement of lesions 
either in the thalamus (27 patients) or globus pallidus (28 patients) for 
treatment of movement disorders.

Patients were evaluated pre- and postoperatively by a team of observers skilled 
in the assessment of gait and movement disorders who were blinded to the 
procedure performed.

The observers were not associated with the surgical team and concomitantly and 
blindly also assessed a group of 11 control patients with Parkinson's disease 
who did not undergo any surgical procedures.

All stereotactic lesions were made with the Leksell gamma unit using the 4-mm 
secondary collimator helmet and a single isocenter with maximum doses from 120 
to 160 Gy.

Clinical follow-up evaluation indicated that 88% of patients who underwent 
thalamotomy became tremor free or nearly tremor free.

Statistically significant improvements in performance were noted in the 
independent assessments of Unified Parkinson's Disease Rating Scale (UPDRS) 
scores in the patients undergoing thalamotomy.

Of patients undergoing pallidotomy who had exhibited levodopainduced 
dyskinesias, 85.7% had total or near-total relief of that symptom.

Clinical assessment indicated improvements in bradykinesia and rigidity in 
64.3% of patients who underwent pallidotomy.

Independent blinded assessments did not reveal statistically significant 
improvements in Hoehn and Yahr scores or UPDRS scores.

On the other hand, 64.7% of patients showed improvements in subscores of the 
UPDRS, including activities of daily living (58%), total contralateral score 
(58%), and contralateral motor scores (47%).

Total ipsilateral score and ipsilateral motor scores were both improved in 59% 
of patients.

One (1.8%) of 55 patients experienced a homonymous hemianopsia 9 months after 
pallidotomy due to an unexpectedly large lesion.

No other complications of any kind were seen.

Neuropsychological test scores that were obtained for the combined pallidotomy 
and thalamotomy treatment groups preoperatively and at 6 months postoperatively 
demonstrated an absence of cognitive morbidity.

Follow-up neuroimaging confirmed correct lesion location in all patients, with 
a mean maximum deviation from the planned target of 1 mm in the vertical axis.

Measurements of lesions at regular intervals on postoperative magnetic 
resonance images demonstrated considerable variability in lesion volumes.

The safety and efficacy of functional lesions made with the gamma knife appear 
to be similar to those made with the assistance of electrophysiological 
guidance with open functional stereotactic procedures.

CONCLUSIONS: Functional lesions may be made safely and accurately using gamma 
knife radiosurgical techniques.

The efficacy is equivalent to that reported for open techniques that use 
radiofrequency lesioning methods with electrophysiological guidance.

Complications are very infrequent with the radiosurgical method.

The use of functional radiosurgical lesioning to treat movement disorders is 
particularly attractive in older patients and in those with major systemic 
diseases or coagulopathies; its use in the general movement disorder population 
seems reasonable as well.


J Neurosurg 1998 Aug;89(2):183-93
Young RF, Shumway-Cook A, Vermeulen SS, Grimm P,
Blasko J, Posewitz A, Burkhart WA, Goiney RC
Northwest Hospital, Seattle, Washington 98133, USA.
<ryoung@xxxxxxxxxx>
PMID: 9688111, UI: 98351397

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janet paterson
52 now / 41 dx / 37 onset
613 256 8340 po box 171 almonte ontario canada K0A 1A0
a new voice: <>
<janet313@xxxxxxxxxxx>