Background: Chronic headache represents a very significant public health and economic issue. One treatment modality for chronic refractory headache involves the use of subcutaneous implanted neurostimulator leads in the occipital region. Varied types of headache etiologies including migraine, transformed migraine, chronic daily headache, cluster headache, hemicrania continua, occipital neuralgia, and cervicogenic headache have been studied with peripheral nerve field stimulation and found responsive to stimulation of the suboccipital region, known commonly as occipital nerve stimulation (ONS).
Objective: To evaluate the strength of evidence that occipital nerve stimulation is an effective treatment of benign headache.
Study design: A systematic review of occipital nerve stimulation for the treatment of chronic headache.
Methods: A systematic review of the literature through EMBASE and PubMed/Medline for clinical studies was performed. The Agency for Healthcare Research and Quality (AHRQ) criteria was utilized to assess the evidence regarding occipital nerve stimulators and arrives at conclusions as to their efficacy in the treatment of headache. Studies were also graded using AHRQ criteria. The overall body of evidence was then graded on a 5 level scale from Level I (conclusive), Level II (strong), Level III (moderate), Level IV (limited) to Level V (indeterminate).
Results: Ten observational studies, of which 4 were prospective, and a number of case series, case reports, and reviews were identified. No randomized controlled trials (RCT) were identified. All of the articles reported positive outcomes including improved pain relief, reduced frequency, intensity, and duration of headaches with reduced medication consumption. ONS was reportedly successful for 70 - 100% of patients. Reduction of pain in patients with occipital headaches and transformed migraine is significant and rapid; for cluster patients the improvement may be less dramatic and it may take several months of occipital stimulation to achieve relief. No long-term adverse events occurred. Several short-term incidents occurred including infection, lead displacement, and battery depletion. The body of evidence as a whole is a level of strength of IV, limited.
Conclusion: ONS is a useful tool in the treatment of chronic severe headaches with at least Level IV (limited) evidence based on multiple positive studies.