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ASTRO: Tremors Respond to Radiosurgery Treatment

By Charles Bankhead

CHICAGO -- Radiosurgery for Parkinson's disease, essential tremor, and trigeminal neuralgia offers efficacy and safety that compare favorably with other treatment options, investigators reported here.

Radiosurgery led to substantial improvement or resolution of symptoms in 80% to 90% of patients in two cohorts, according to Rufus Mark, MD, of Texas Tech University in Lubbock. The results suggest radiosurgery be considered as initial therapy for patients with medically refractory forms of the neurologic disorders.

"The results are as good or better than what has been observed with other treatment modalities," Mark said in an interview at the American Society for Radiation Oncology meeting.

"Compared with other, more invasive treatment options, radiosurgery has a lower risk of complications, particularly major complications."

Mark and colleagues reported data from two separate clinical series using gamma knife radiosurgery. One series comprised 511 patients with medically refractory trigeminal neuralgia, and the other included 183 patients with medically refractory Parkinson's disease or essential tremor. All patients were treated from 1991 to 2007.

The trigeminal neuralgia cohort included 158 (30.1%) patients who had undergone a total of 356 neurosurgical procedures prior to radiosurgery. All patients had typical trigeminal neuralgia, and treatment targeting was determined by means of CT and MRI scans and by inversion recovery MRI.

In all cases, radiosurgery was applied to the cranial nerve V entry root zone into the brain stem. The prescribed radiation dose ranged from 70 to 90 Gy administered in a single treatment session. Response to treatment was categorized as:

  • Excellent (no pain, off all analgesics)
  • Good (no pain with use of analgesics)
  • Poor (continued pain despite analgesics)


After a median follow-up of 10 years, 54.2% of patients had an excellent result and 23.1% had a good result. Investigators observed a dose-response relationship, as the proportion of patients with an excellent or good response was 55.7% when treated with a 70-Gy dose of radiation, increasing to 82.4% for 80 Gy and 86.2% with 90 Gy (P<0.01).

Treatment-emergent adverse effects included temporary ipsilateral facial numbness in 18.8% of patients, permanent facial numbness in 5.1%, loss of corneal reflex in 1.4%, and painful dysesthesias in 2.7%.

Treatment also had a dose-dependent impact on facial numbness, as 6.5% of patients had temporary numbness with a radiation dose of 70 Gy, 17.1% at 80 Gy, and 29.3% at 90 Gy (P<0.01). The incidence of permanent numbness was 2.5 with 70 Gy, 3.2% with 80 Gy, and 9.0% with 90 Gy.

On the basis of the results, Mark and colleagues concluded that 80 Gy is the optimal radiation dose to achieve the best risk-benefit ratio for patients with medically refractory trigeminal neuralgia.

Patients with medically refractory Parkinson's disease or essential tremor have several treatment options, including deep-brain stimulation, radiofrequency ablation, and radiosurgery.

Previous studies showed comparable efficacy among the treatment modalities but possibly fewer complications after radiosurgery.

To add to the evidence base, Mark and colleagues reported their experience with radiosurgery in 116 patients with Parkinson's disease and 67 with essential tremor that had not responded to medical treatment.

The treatment plan targeted the ventralis intermedius nucleus in all cases, and the prescribed dose for all patients was 140 Gy administered in a single session.

Treatment effect was assessed by means of the Unified Parkinson's Disease Rating Scale and the Clinical Rating Scale for Tremors.

After a median follow-up of seven years, 82.8% of patients with Parkinson's disease had significant or complete resolution of tremors, as did 86.6% of patients with essential tremor.

Adverse events consisted of MRI-proven edema and transient hemiparesis in three patients. The effects resolved in response to high-dose steroids in two patients and to high-dose steroids and hyperbaric oxygen in the third. No hemorrhages or infections occurred, and no patient died.

"In view of these long-term good results and low complications risks, radiosurgery should be considered as a primary initial treatment in medically refractory tremors," the investigators concluded in a poster presentation.

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