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The Unknown Headache

The unknown headache is the “lower-half” headache. Another name for “lower-half” headache is “facial migraine.” Neil Raskin, MD, headache neurologist, in his book Headache (1988) cited the vascular characteristics of chronic recurring facial pain that “should not deter the diagnosis of a migraine variant.”


Dr. Raskin wrote that such observations were “innovative and important,” but largely overlooked as representing a primary headache disorder.


Clearly, Dr. Raskin concluded that migrainous pain can occur in the maxillary and mandibular dermatomes of the trigeminal nerve. Enclosed in these lower facial dermatomes are anatomical structures not commonly understood to be involved in migraine pathophysiology. These structures include the muscles of mastication, TMJ and teeth. In addition, the mucous membranes of the nasal sinuses, and air cells of the mastoid processes are innervates by the maxillary and mandibular divisions of the CNV, respectively.


Confirmation of the neuroanatomical basis of “lower-half” headache or facial migraine is found in Gray’s Anatomy: “The middle meningeal nerve is given off (in the middle cranial fossa) from the maxillary nerve directly after its origin from the trigeminal ganglion; it accompanies the middle meningeal artery and supplies the dura mater.” Moreover, “The meningeal branch of the mandibular nerve enters the skull through the foramen spinosum with the middle meningeal artery. It divides into two branches (in the middle cranial fossa), which accompany the anterior and posterior divisions of the artery and supply the dura mater. The anterior branch communicates with the meningeal branch of the maxillary nerve.” Interestingly, “the posterior branch sends filaments to the mucous membrane of the mastoid cells.”



Diagnostic Schema


How does a clinician diagnos “lower-half” headache? The answer is simple: Ask the patient the same questions regularly asked to diagnose migraine elsewhere. Ask: “When the lower face pain is most severe and at its greatest intensity, do you have nausea, light sensitivity or sound sensitivity? Is there a family history of headache?” Herein, these questions point to the most common associated features of migraine: nausea (88 percent), photophobia (83 percent) and phonophobia (76 percent). In addition, 90 percent of migraine patients have a familial history of headache.


Watch out - the patient can fool you! If the patient tells you that the extreme facial pain was so bad that the pain itself “made me nauseated or made me throw-up,” be skeptical. Worse pains than migraine, such as tic pain, are not commonly associated with nausea, vomiting, photophobia or phonophobia. Alternatively, the patient may blame the nausea  and/or vomiting on medications that she/he is taking for the extremely severe facial pain. This may be true, but unlikely, if other common associated features are present.


Obviously, one must rule out other conditions of the lower half of the face: sinus headache, trigeminal neuralgia, carotid system arteritis, TMJ dysfunction, and dental pathology. Comorbidity of migraine with any of these conditions complicates pattern-recognition of the pain presentation. Comorbidity increases the chances of making a Type 2 error: believing that a pattern is not real when it is. Another complication of diagnosing lower-half headache is that seen in common migraine located elsewhere, i. e., the severe migrainous attack may have no associated features.



Pathophysiology of “Lower-half headache”


Given that branches of the maxillary and mandibular divisions of CNV innervate the dura mater, how does the extra-cranial anatomy of the lower face receive sensory input from the intra-cranial vasculature imbedded in the meninges? The illness of “lower-half” headache is a story of trigeminal nociception that is centrally-mediated based on the neurological concept of viscera-somatic convergence. Peripherally, the viscera is intra-cranial representing the meninges, and the soma is extra-cranial representing the maxillae and mandibular structures forming the carriage of the lower face. Importantly, neuronal innervations of the visceral meninges are the first, second or third divisions of CNV. Whereas, the neuronal innervations of the somatic facial anatomy are the second or third divisions of CNV.


Gray’s Anatomy documents that all three divisions of CNV innervate the meninges. The meningeal nerve of the maxillary nerve innervates the meninges of the anterior wall of the middle cranial fossa. The meningeal branch of the mandibular nerve, also known as the nervus spinosum, innervates the remaining meninges of the middle cranial fossa. The largest population of meningeal neurons are nociceptors. The somatosensory innervations of the maxillo-mandibular complex that subserve pain are nociceptors whose first central synapse is in the superficial lamina of the medullary dorsal horn.


Within the superficial lamina are cell bodies of second-order pain transmission neurons that normally transmit signals from maxilla-mandibular nociceptors via the trigemino-thalamic tact to rostral perception areas that are discriminative for pain of the lower face. Importantly, the first central synapse of some visceral nociceptors of the meninges converge on the second-order somatic trigemino-thalamic neurons. Thus, the identical central target of the peripheral meningeal nociceptors and the lower face nociceptors represent viscera-somatic convergence.


Under normal conditions, the synapse of peripheral meningeal nociceptors onto central trigemino-thalamic neurons are silent. During an acute attack of migraine, these silent synapses become awake and active resulting in stimulation of the second-order neurons followed by propagation of pain signals rostrally that are ultimately perceived as severe pain attacks in the lower face.


Moreover, the truth is that the extra-cranial peripheral dermatomes of CNV as seen in diagram 1 are different than the intra-cranial peripheral dermatomes of CNV.


The consequence of this truth is related to lower-half headache. The tentorial branch of the ophthalmic division of CNV arises near the trigeminal ganglion and runs between the layers of the tentorium to which it is distributed. The tentorial branch of CNV innervates the entire tentorium that extends posteriorly all the way back to the internal occipital protuberance, as well as all of the meninges above the tentorium.


Thus, migraine in the occipital area can be a trigeminal pain that has the potential to participate in the neurological mechanism viscera-somatic convergence resulting in pain perceived in the lower half of the face.


Note with careful interest the yellow circle behind the ear in diagram 5. Traditionally, the extra-cranial dermatome for this area is known to be C2, i. e., the lesser occipital nerve distribution. On the other hand, the sinus lining of the mastoid air cells deep to the skin is innervated by a small branch of the mandibular division of CNV. Based on pathophysiology of lower-half headache described above, meningeal migraine pain can refer lower-half pain to the back of the head behind the ear.



Treatment


Strategies for the treatment of “lower half headache” follow the same well-published and standard protocols of care for migraine anywhere else in the head. For example, abortive medications are recommended for severe attacks occurring less than 15 days per month. Whereas, more frequent attacks may require a daily preventative medication regiment. Botox can also be used in the muscles of mastication.



Summary


Recurrent severe jaw pain associated with vascular elements in the lower half of the head caused by migraine is called “lower-half” headache or facial migraine. Recognized as a primary headache disorder, the severe pain is located in the maxillae and/or mandibular dermatomes of CNV. Associated features of “lower-half” headache are identical to common migraine – nausea, photophobia and/or phonophobia. Most patients fail to recognize these manifestations as associated features of migraine. In some cases, no associated features occur which makes diagnosis difficult. In addition, comorbidity of “lower-half” headache together with maxillo-mandibular pathologies makes diagnosis difficult. Therefore, a multidisciplinary approach is recommended.



Brian D. Fuselier, DDS is a member of the International Association for the Study of Pain, and the American Pain Society.


Barry A. Loughner, DDS, MS, PhD is a member of the International Association for the Study of Pain, the American Pain Society, the American Dental Association, and the Ethics Committee of the American Association for the Study of Headache.


Dr. Fuselier and Dr. Loughner are actively practicing at Central Florida Oral and Maxillofacial Surgery. This practice is unique as they have both Oral Surgeons and Facial Pain Specialists practicing together. For more information visit www.cforalsurgery.com



 
 
 
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