Occipital nerve stimulation eases headaches and stimulates debate

The treatment of chronic neuropathic pain using nerve stimulation has been used for many years, both in the spinal cord (SCS) and peripheral nerves (PNS).  However, the treatment of pain in the craniofacial region remains a challenge due to the high incidence of surgical complications and revisions. A recent study assessed the complications of occipital nerve stimulation surgery.1

Benefits of nerve stimulation

The efficacy of occipital nerve stimulation for occipital neuralgia has been documented in previous studies.  Better pain control and reduced use of oral pain medications was documented in 70% of patients treated for occipital neuralgia.² Similarly, ~90% of patients treated for C2-mediated occipital headaches reported reduced use of medications, and 64% had fewer headaches.³ Treatment of migraine syndromes using occipital nerve stimulation has resulted in similar benefits – 60% of patients experienced a 30% reduction in headache severity and frequency,⁴ and patients with transformed migraines showed a 50% reduction in frequency or severity of headaches.⁵

Equipment issues and complications

Currently, the equipment used for occipital nerve stimulation to induce an anti-nociceptive effect is the same as that used for spinal cord stimulation. Thus the complications are similar for both spinal cord and occipital nerve stimulation, including lead migration, infection, pain and equipment malfunction. A limited number of studies on small sample sizes of patients have reported lead migration in 9–100% of patients and pain in 2–10% of patients.¹

Recently, Falowski et al.¹ reviewed the complications and surgical procedures of patients undergoing occipital nerve stimulation surgery at a single centre, with follow-up of up to 60 months in some patients. The most common complication was lead migration, occurring in seven of 28 patients; these seven patients underwent a total of 13 revision surgeries and all lead migrations required surgical intervention. These revisions occur throughout the 60-month follow-up period, indicating that lead migration does not occur more frequently during the acute period following implantation. Three of the lead migrations occurred secondary to trauma that resulted in lead displacement.¹

Lead migration

The surgical technique evolved during the study period, and some patients received an additional strain relief loop through a second incision. The use of a second strain relief loop only had a 10% revision rate, compared to ~63% for patients who did not receive the strain relief loop. Lead migration occurred in only two patients with the second strain relief loop, and followed trauma in both cases. Thus the revision rate for primary lead migration in patients with the second strain relief loop was 0% over 60 months.¹    

Infections

Five of the 28 patients developed infections. Four of these were treated with oral antibiotics, while one patient required a 6-week course of intravenous antibiotics. The site of infection varied between patients, and included the sites of the implantable pulse generator (IPG) in the buttock or abdomen, the cervical incision and the second incision.¹

Ineffectiveness

The stimulators were removed in five patients who felt that it was not effective in alleviating pain. Another patient disliked the sensation that occurs with stimulation and also had the device removed.¹ 

Battery-related pain

Five patients experienced pain at the battery sites (buttocks and chest). None of the patients fitted with a battery in the abdomen experienced pain at the battery site, except for a single patient who experienced persistent pain with the battery in the buttocks or abdomen. Battery revision for migration occurred in one patient with the battery implanted in the buttock, and one with a chest implant. Battery migration was not documented for any of the abdominal battery implants.¹ 

There were an additional four surgeries for IPG change due to end of life of the battery, and one IPG revision secondary to battery malfunction following trauma to the area.

In summary

In total, 59 surgeries were performed in 28 patients fitted with occipital nerve stimulators. Patients underwent between one and five surgeries during the 60-month follow-up period.  The revision rate was greater than that with spinal cord stimulation; this is likely due to the use of SCS equipment rather than a specially developed apparatus for occipital nerve stimulation.

A 60% revision rate for migration within six weeks of implantation has previously been documented using cylindrical electrodes, compared to ~25% over a 60-month follow-up period in the present study. The use of paddle-shaped electrodes (as used in this study) is thought to result in more effective anchoring of the electrodes, helping to reduce migration.¹     

Suggestions for minimising adverse effects

The most dramatic findings of this review are the absence of lead migration in patients who received an additional strain relief loop (10% vs. 63%); the reduced incidence of pain at the battery site in the abdomen; and the absence of battery migration at this site compared to at the buttocks and chest. These findings suggest that an additional strain relief loop and abdominal battery implantation is best practice for reducing the adverse events of occipital nerve stimulator surgeries. The high revision rates for these surgeries are likely to result in re-evaluation to determine whether the effectiveness of occipital nerve stimulation as a treatment option for various syndromes outweighs the high number of surgical revisions.¹ 

References

1. Falowski S, Wang D, Sabesan A, Sharan A. Occipital nerve stimulator systems: Review of complications and surgical techniques. Neuromodulation. 2010;13(2):121-5. [Abstract] 
2. Slavin KV, Nersesyan H, Wess C. Peripheral neurostimulation for treatment of intractable occipital neuralgia. Neurosurgery. 2006;58(1):112-9. [Abstract]
3. Melvin EA Jr, Jordan FR, Weiner RL, Primm D. Using peripheral stimulation to reduce the pain of C2-mediated occipital headaches: A preliminary report. Pain Physician. 2007;10(3):453-60. [Abstract]
4. Schwedt TJ, Dodick DW, Hentz J, et al. Occipital nerve stimulation for chronic headache: Long-term safety and efficacy. Cephalalgia. 2007;27(2):153-7. [Abstract]
5. Popeney CA, Aló KM. Peripheral neurostimulation for the treatment of chronic, disabling transformed migraine. Headache. 2003;43(4):369-75. [Abstract]