Background: Stimulation of the greater occipital nerve has been employed for various intractable
headache conditions for more than a decade. Still, prospective studies that correlate stimulation of the
greater occipital nerve with outcome of patients with respect to alleviation of headache are sparsely
found in literature.
Objective: To identify anatomical landmarks for a reproducible stimulation of the greater occipital
nerve. For the clinical implication, the individual response to therapy of patients with refractory
chronic cluster headache undergoing occipital nerve stimulation was correlated with the postoperative
localization of the electrodes and with the distribution of the stimulation field.
Study Design: Prospective observational study, approved by the local research ethics board (09-4143).
Setting: University hospital, departments of neurosurgery and neurology, institute of anatomy and
radiology.
Methods: Ten formaldehyde fixed human cadavers were dissected to identify the passage of the
greater occipital nerve through the trapezius muscle. The distance to the external occipital protuberance
was triangulated measuring the distance of the nerve from the nuchal midline and the protuberance.
Between December 2008 and December 2011, 21 consecutive patients suffering from chronic cluster
headache underwent surgery in terms of bilateral occipital nerve stimulation, with electrodes placed
horizontally at the level of C1. The postoperative x-rays were compared with the acquired landmarks
from the anatomical study. The distribution of the stimulation field was correlated to the individual
response of each patient to the therapy and prospectively analyzed with regard to reduction of daily
cluster attacks and relief of pain intensity at 3 months and at last follow-up.
Results: The greater occipital nerve crosses the trapezius muscle at a mean distance of 31mm below
the occipital external protuberance and 14mm lateral to the midline as found in the anatomical subjects.
The electrodes were targeted at this level in all of our patients and stimulated the greater occipital nerve
in all patients. Eighteen of the patients (85.7%) reported a significant reduction of the frequency of
their cluster attacks and/or declined intensity of pain during the attacks. Yet, 3 of 21 patients (14.3%)
did not benefit from the stimulation despite an adequate spread of the stimulation over the occiput.
The spread of the stimulation-induced paraesthesias over the occiput was not correlated to a reduction
of cluster attacks, to the intensity of attacks, or to the response to treatment at all.
Limitations: Single center non-randomized non-blinded study.
Conclusions: From our study we conclude that a reproducible stimulation of the greater occipital
nerve can be achieved by placing the electrodes parallel to the atlas, at about 30mm distance to the
external occipital protuberance. The response to the stimulation is not correlated to the field width of
the paraesthesia. We, therefore, consider stimulation of the main trunk of the greater occipital nerve to
be more important than a large field of stimulation on the occiput. Still, an individual response to the
occipital nerve stimulation cannot be predicted even by optimal electrode placement.
Key words: Greater occipital nerve, occipital nerve stimulation, anatomical study, chronic cluster
headache
Trigeminocardiac Reflex Induced by Maxillary Nerve Stimulation during Sphenopalatine Ganglion Implantation: A Case Series
