Occipital neuralgia (ON) is a neurological disorder that commonly involves the greater occipital and less commonly the lesser occipital nerves.1 Trauma of the C2 root such as excessive movements (whiplash injuries) of the head and arthritic changes of the atlantoaxial joint are considered the most common causes of ON,1 but prolonged contraction or spasm of the posterior neck muscles from a variety of causes has also been implicated.1 The quality of the pain is classically similar to trigeminal and glossopharyngeal neuralgia but is localized in the occipital and periauricular areas, and may radiate into the retro-orbital area.2 As with neuropathic pain in other nerve distributions, a constant, nonlancinating pain is also common and may be termed as occipital neuropathic pain.
The concept of neuromodulation for the treatment of chronic intractable pain was developed almost 50 years ago.3 Although the Melzack-Wall gate control theory was generally accepted in the past, alternative mechanisms have been demonstrated to be responsible for the suppression of pain during neurostimulation such as4,5:
Direct block of depolarization of the A-alpha, A-beta, and the A-delta fibers, as well as axonal conduction block are currently more accepted as the mechanisms of pain modulation from nerve stimulation.6
Torebjork and Hallin demonstrated that repetitive stimulation of peripheral nerves results in excitation failure of C fibers thought to be responsible for conduction of painful stimuli.7
Alternatively, peripheral nerve stimulation may block more distal nociceptive input by inhibitory action at the dorsal horn, brain stem, thalamus, or parietal cortex.8
The pathophysiological mechanisms responsible for pain control in ON with PNS are complex, and much remains to be learned. In 1999, Weiner and Reed reported percutaneous implantation of cylindrical electrodes in the vicinity of the occipital nerves for occipital neuralgia.9 Shortly thereafter, transformed migraines, that combine the features of both migraine and tension-type headache, were also treated with this technique.10 This relatively straightforward and less invasive approach quickly gained popularity and developed in terms of electrode type, insertion procedure, and indications.11 In 2003, Popeney and Alo postulated that the partial convergence of afferents from the occipital and frontotemporal region may account for a better clinical outcome with combined stimulation of the trigeminal and occipital nerves (ie, the trigeminocervical tract).12 This was later confirmed by others10, 11, 12, to 13 including Reed et al, who stimulated both the occipital and trigeminal systems in patients of refractory to ONS and ongoing holocephalic migraine.13 Their results support the need to evaluate both the C1-2-3 roots (occipital) and the supraorbital (trigeminal V1)/superficial temporal (trigeminal V3) nerves in refractory holocephalic headache.
PNS for the treatment of occipital neuralgia was described by Weiner9 in 1999 (Figure 74-1). Indications later expanded to include: