learn more at: dose-response and dose- complications relationships in stereotactic radiosurgery for...
TRANSCRIPT
Learn More At:www.DoctorVermeulen.com
Dose-Response and Dose-Complications Relationships in Stereotactic Radiosurgery for
Trigeminal Neuralgia
Sandra Vermeulen MD, Robert Meier MD, Vivek Mehta MD, Ron Young MD, Francisco Li MS
Northwest Gamma Knife Center, Seattle, WA, USA
Learn More At:www.DoctorVermeulen.com
Trigeminal Neuralgia: Overview• Definition: brief episodic, unilateral face pain,
confined to one or more divisions of the 5th nerve.
• Cause: tumors, vascular compression of the root entry zone, multiple sclerosis and idiopathic causes
• Pharmacotherapy is the initial treatment modality of choice
• Annual incidence in the United States: 15,000
Learn More At:www.DoctorVermeulen.com
Purpose/Objective
In Patients treated with Gamma Knife Radiosurgery for Trigeminal Neuralgia, to
determine if a relationship exists between dose delivered, and the incidence of response, or the
incidence of complications
Learn More At:www.DoctorVermeulen.com
Material and Methods
• 382 patients with either typical or atypical TN were treated between August 1993 and January 2005
• None had tumor or Multiple Sclerosis
• All were treated with a single 4-mm isocenter targeting the ipsilateral trigeminal nerve at the dorsal root entry zone
• Dose was prescribed at the Dmax
Learn More At:www.DoctorVermeulen.com
Dose Protocols
Three dose protocols were employed using an output factor or 0.87:
76 patients received 76 Gy
179 patients received 87 Gy
127 patients received 98 Gy
Learn More At:www.DoctorVermeulen.com
Patient CharacteristicsGroup
Dose
Group 1
76 Gy
Group 2
87 Gy
Group 3
98 Gy
Patient No. 76 179 127
Mean F/U 4.16 yrs 2.74 yrs 3.76 yrs
Sex (M/F) 26/50 68/111 50/77
Mean Age 63 yrs 62 yrs 60 yrs
Location R/L 48/28 99/80 61/66
Division No. >1: 48 >1: 109 >1:70
Pre-GK Procedures
None/1/>1
41/16/19
None/1/>1
119/25/35
None/1/>1
89/17/21
Learn More At:www.DoctorVermeulen.com
Treatment Characteristic
Isodose 20% 30% 40% 50%
Group 1
76 Gy11% 1% 63% 25%
Group 2
87 Gy40% 28% 0% 32%
Group 3
98 Gy63% 0% 0% 37%
Learn More At:www.DoctorVermeulen.com
ResultsTreatment outcomes were measured at 6 months,
at last follow-up and actuarially
“Favorable” responders were patients rendered free of pain, either with or without medication
Complications were defined as lasting neurologic deficits attributable to treatment and included
numbness or paresthesias
Learn More At:www.DoctorVermeulen.com
Pain Relief
• At 6 months post-treatment, “favorable” outcomes occurred with similar rates in all 3 groups
• Log-rank test showed no significant difference in the Kaplan-Meier curves for these three groups (p=0.835)
0
10
20
30
40
50
60
70
80
90
100
76Gy
87Gy
98Gy
ResponseRate toGammaKnife RS
Learn More At:www.DoctorVermeulen.com
Complications
• The only lasting complication was new numbness or paresthesia
• At 6 months, patients treated with higher doses more often developed sensory deficits (p<0.05)
0
10
20
30
40
50
60
70
80
90
100
76Gy
87Gy
98Gy
Rates OfSensoryDeficits
Learn More At:www.DoctorVermeulen.com
Severity of Numbness
0
10
20
30
40
50
60
70
80
90
100
76Gy 87 Gy 98 Gy
Not Bothersome
Bothersome
Painful