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					                    Discussion


The Anatomy of the Greater Occipital Nerve: Implications for
the Etiology of Migraine Headaches
Discussion by Eric David Austad, M.D.
San Diego, Calif.


   This work addresses a topic that I believe to             muscle but otherwise traverses fascial planes.
be the most interesting and potentially revolu-              No other muscle typically invests the nerve.
tionary concept engaging plastic surgeons in                 They locate the specific point at which the
the past 10 years. Specifically, it relates the              greater occipital nerve can be expected to be
anatomy of the greater occipital nerve to exter-             coursing through the semispinalis muscle,
nal landmarks, and it reviews the apparent role              finding the target zone of the botulinum toxin
of that nerve as an etiology of a clinical prob-             A block to be 3 cm below the external occipital
lem that affects approximately 28 million peo-               protuberance and 1.5 cm lateral to the mid-
ple in the United States: migraine headache.                 line. These measurements are similar to those
As an anatomical study, it is well designed and              of Bovim et al.,1 but the additional information
cogently presented. As a therapeutic construct,              regarding the distribution of these measure-
it expands upon the senior author’s working                  ments is reassuring. If the pharmacologic ef-
hypothesis that “the underlying etiology of mi-              fect of botulinum toxin A is limited to neuro-
graine symptomatology may be peripherally                    muscular blockade, it is obviously critical to
rather than centrally mediated.” The basis of                know where muscle and nerve are intimately
this argument that chronic compression by                    related, i.e., this is the place, and the only
skeletal muscle surrounding a sensory nerve                  place. As a final observation of the experimen-
can serve as a trigger point for migraine is the             tal model, it should be noted that this study
observation by many different sources that bot-              describes the course of the greater occipital
ulinum toxin A chemoblockade is often effec-                 nerve in a “normal” population. It is possible
tive in eliminating migraine pain for several                that some or all migraine patients experience
months. This is a startling concept, quite                   headache because their anatomical relation-
counter to the traditional views of migraine as              ships are not normal. This is not a criticism of
a complex phenomenon reflective of the intra-                this work, because an anatomical study of head
cranial interplay of neurotransmitters, external             pain patients would present significant difficul-
stimuli, genetics, and emotional factors. As                 ties, and in any case, a “normal” baseline is
such, it has been met with skepticism by many                necessary for significant abnormalities to be
neurologists and other pain management                       appreciated.
specialists.                                                    Botulinum toxin A blockade for headache
   Before considering the theoretical implica-               serves two purposes. First, it offers some signif-
tions of this article, it may be useful to reiterate         icant chance of long-term pain relief, usually
its anatomical goal: describing the course of                lasting 2 to 4 months. This is generally very
the greater occipital nerve “so that points of               similar to the duration of the effect of botuli-
chemodenervation using external landmarks                    num toxin A on muscle. A second value of
can be used to relieve migraine symptoms.”                   botulinum toxin A chemoblockade of the semi-
The authors found, in dissections of cadavers                spinalis muscle or the muscles of the brow is
with no known history of migraine, that this                 diagnostic; relief suggests that muscle is play-
nerve reliably courses through the semispinalis              ing an active role in causing pain. This is di-

   Received for publication September 23, 2003.
   DOI: 10.1097/01.PRS.0000101519.86223.64
                                                       698
Vol. 113, No. 2 /    DISCUSSION                                                                               699
rectly analogous to the use of local anesthetic                 sion. I believe that this is analogous to a herni-
nerve blockade in other clinical situations,                    ated spinal disc causing nerve root pain or to
such as meralgia paresthetica, to diagnose                      pain resulting from compression of the median
nerve irritation or compression. If the only                    nerve in the carpal canal. These anesthetic
effect of botulinum toxin A is its interference                 blocks often contain steroids as well and are
with acetylcholine release at the neuromuscu-                   placed in a horizontal band along the nuchal
lar junction, weakening or paralyzing the in-                   line. This is approximately 2 to 3 cm more
jected muscle, this logic is valid. Unfortunately,              cephalic than the botulinum toxin A blocks
if one prefers straightforward solutions, many                  under discussion here. There would appear to
neurologists hypothesize that botulinum toxin                   be little logic in using botulinum toxin A at
A also causes “central” nervous system effects                  that level. There is simply no muscle surround-
that, while poorly elaborated, somehow cause                    ing the greater occipital nerve as it exits the
pain relief. I do not find the evidence for the                 trapezius fascia and branches beneath the oc-
existence of these other effects to be compel-                  cipital scalp. Thus, I believe that there is diag-
ling. It is difficult to imagine a local anesthetic-            nostic value to both botulinum toxin A and
type response or a morphine-like effect lasting                 local anesthetic/steroid blocks in evaluating
for several months.                                             headache. The former is appropriate proxi-
   As a final point, the authors focus on the                   mally, at the point identified by these authors.
relationship of the greater occipital nerve to                  This is the only site of potential muscle com-
the semispinalis muscle but do not discuss                      pression. More distally, local anesthetic is the
other sites of potential compression of this                    logical agent to determine whether nerve com-
nerve. Until recently, my experience with ex-                   pression is resulting from a structural abnor-
ploration and decompression of the greater                      mality at a more superficial level.
occipital nerve for pain was limited to the more                   In summary, I share the belief of these
superficial course of the nerve after its exit                  authors that headache, whether classified as
from the semispinalis muscle. In a large series                 migraine or one of the many other diagnos-
of patients treated during the last 30 years and                tic types of head pain, often arises from irri-
reported somewhat anecdotally in this Journal a                 tation or compression of peripheral sensory
few years ago,2 I relied on local anesthetic                    nerves of the face or occipital region. Is it
block responses as my primary indication for                    possible that this major health problem,
decompression of the nerve at its exit point                    which often results in significant disability
from the trapezius fascia. At that level, I often               and is refractory to the efforts of pharmaceu-
encounter significant lymphadenopathy (Fig.                     tical companies and other sources of treat-
1) or an anomalous relationship of the occipi-                  ment, is frequently a simple mechanical phe-
tal artery to the nerve; both of these often                    nomenon? The ongoing work of Dr.
appear to be definite sources of nerve compres-                 Guyuron and his coauthors, as reported in
                                                                two previous articles and further refined by
                                                                this current study, is compelling. It is appro-
                                                                priate to doubt that a simple explanation for
                                                                a disorder long believed to be highly com-
                                                                plex and multifactorial could be valid in this
                                                                age of sophisticated science. In that regard,
                                                                the recently appreciated relationship of pep-
                                                                tic ulcer disease to chronic infection by Hel-
                                                                icobacter pylori should be recalled. In that ill-
                                                                ness, factors of emotion and personality type,
                                                                in addition to other systemic and often mys-
                                                                terious causes, were considered to be of pri-
                                                                mary importance for many years. Finally rec-
                                                                ognizing that a “simple” chronic infection is
                                                                a major cause of most peptic ulcer disease
                                                                was enlightening and appropriately hum-
   FIG. 1. Greater occipital nerve exposed at the exit point    bling. The work of Dr. Guyuron and his col-
from trapezius fascia, with the perineural lymph node causing   leagues will ultimately be confirmed or re-
apparent compression.                                           futed by studies at other centers; these are in
700                                                PLASTIC AND RECONSTRUCTIVE SURGERY,           February 2004
progress. With these, the appropriate role of                              REFERENCES
plastic surgeons in the treatment of head            1. Bovim, G., Fredriksen, T. A., Stolt-Nielsen, A., and Sjaas-
pain will be defined. Stay tuned.                         tad, O. Neurolysis of the greater occipital nerve in
                 Eric David Austad, M.D.                  cervicogenic headache: A follow-up study. Headache
                                                          32: 175, 1992.
                 4510 Executive Drive, Suite 105     2. Austad, E. Relevance of the lesser occipital nerve in
                 San Diego, Calif. 92121-3022             facial rejuvenation surgery (Discussion). Plast. Recon-
                 eaustad@compuserve.com                   str. Surg. 105: 2600, 2000.

				
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