Delaying stereotactic radiosurgery worsens trigeminal neuralgia pain outcomes

By Lucy Piper, Senior medwireNews Reporter

Delaying stereotactic radiosurgery worsens trigeminal neuralgia pain outcomes

Stereotactic radiosurgery (SRS), as a first surgical procedure for medically refractory trigeminal neuralgia, should be performed within 3 years of pain onset to achieve the best results, researchers recommend.

They found that carrying out the procedure within this time frame offered faster, better and longer pain relief compared with delaying surgery beyond 3 years.

“Both inadequate pain relief and facial numbness occurred more often in patients with a longer history of pain”, say researcher Ajay Niranjan (University of Pittsburgh Medical Center, Pennsylvania, USA) and team.

In all, 121 patients aged a median of 72 years underwent Gamma Knife SRS, receiving an average maximum dose of 80 Gy to the trigeminal nerve target.

Initial pain relief was achieved by 107 (88%) patients, based on a Barrow Neurological Institute (BNI) score of I–IIIa, after a median of 1 month. The researchers note in Neurology that the time to pain relief was significantly shorter if patients underwent SRS within 3 years of pain onset, at a median of 1 week compared with 6 weeks for those whose pain had persisted for more than 3 years.

Patients with a shorter duration of pain before surgery also had adequate pain control for longer after surgery, increasing from a median of 36 months among patients who underwent SRS within 3 years to 10 months among those whose surgery was delayed for more than 3 years.

This benefit also extended to the time patients spent free of pain without needing medication (BNI-I), which was maintained for 5 and 10 years in 73% and 40% of patients who underwent SRS within 3 years of diagnosis, compared with 8% and 0% of the patients who received surgery after 3 years.

Even after taking into account factors that increased the likelihood of early referral for SRS, such as evidence of vascular compression of the trigeminal nerve, referral within 3 years of diagnosis was the only factor significantly associated with increased duration of pain relief.

There was also evidence to suggest that it may lessen the chances of secondary sensory dysfunction after SRS, as the 12% of patients who developed dysfunction a median of 12.5 months after surgery had a longer duration of pre-surgery pain than non-affected patients, at 121.0 versus 83.9 months.

“SRS performed within 3 years of pain onset was associated with longer and more complete pain relief”, the researchers write.

They acknowledge, however, that “like other cyclical neurologic disorders, trigeminal neuralgia pain might subside even without surgical intervention in patients with shorter history of pain”.

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