Trigeminal Neuralgia (TN) – How Good is the Gamma Knife?

Radiation “knifing” trigeminal nerve appears to be a safe and effective alternative in Trigeminal Neuralgia – though used more in people unable to tolerate microvascular decompression.

No Shinkei Geka. 2013 Dec;41(12):1065-74.
[Gamma knife radiosurgery for trigeminal neuralgia: analysis of a multi institutional study].[Article in Japanese]
Takanashi M, Fukuoka S, Ozaki Y, Satou K, Oikawa M, Nakamura H.

  • Often a back up plan as 369 had prior percutaneous nerve block and 173 patients had undergone microvascular decompression(MVD) prior to GKRS
  • Gamma Knife radiosurgery [GNRS] is done in Winnipeg, Manitoba near here. 
  • I can only give you info written in abstract… japanese is a little rusty :)
  • 689 patients
  • 69.4%  targeted at the nerve root entry zone(REZ)and for 20.4% of patients targeted at the retrogasserian region(RGR).
  • The target dose of the GKRS varied from 70 to 90 Gy(mean:77.8Gy)
  •  Initially – 66%  excellent or good control(pain free),  15% fair control(more than 50% relief), and 19% (192) failed
  • After 3 years –  64% were pain free and 80% >  50% pain relief.
  • Alternatives for faliures? – after 4 years – 37 patients underwent additional GKRS, 36 MVD (microvascular decompression) and 36 percutaneous nerve block. – that would be 99/689 = 15%
  • Tolerable  numbness (hypoesthesia or paresthesia) in 11%,  bothersome numbness  in1%. 
  •  No new (deafferentation)  pains.
  • 1% dry eye, but no eye lesions found.

Comment – I would think if well enough, microvascuolar decompression should be tried first, and then if it fails, then GNRS could be tried.  However, there is over a 50% chance that gamma knife will do the job so in more fail cases, it is acceptable treatment.

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