Atypical Facial \"Neuralgia

Atypical Edwin

Facial “Neuralgia”

D. Dunteman,

Pain Management

MD,

MS,

Center, Department

and Robert A. Swarm, of Anesthesiology,

Washington

T

here are many causes of head and facial pain (1). As with pain in other regions, myofascial origin is often not considered. One myofascial pain syndrome often missed arises from the masticatory muscles and has been termed myofascial pain dysfunction syndrome (MPD). Multiple symptoms and referred pain patterns throughout the head and neck mimic extensive disease syndromes (2-4). Problems arising from this area are frequently misdiagnosed, often resulting in unnecessary or improper treatments, leading this syndrome to be labeled as “The Great Impostor.” (5,6).

Case Report A 70-yr-old female presented with a 5-yr history of severe left-sided facial pain and headache. She described a prolonged and complicated course of therapy, delivered by a variety of physicians from several medical centers. She complained of chronic left-sided throbbing and frequent “sharp,” “shooting” pains in the mandible, upper gums, teeth, cheek, and temporal regions. “Jaw spasms” with “twisting in the mouth” often hampered eating and sleeping. Her lowest reported Visual Analog Pain Scale rated 8 on the O-to-10 scale, but averaged 9/10. Pain was worsened by eating or talking to lO/lO. Typically worst in the morning, the pain lessened gradually throughout the day. She also noted left-sided hearing difficulty, chronic nasal congestion (left worse than right), and frequent sore throats. Past history included multiple dental procedures before and after symptom onset. Prior therapies, all without significant benefit, had included: maxillary bone resection, trigeminal nerve blocks, carbamazepine, phenytoin, amitriptyline, various opioids, and nonsteroidal antiinflammatory agents. Previous evaluations, including magnetic resonance imaging, nerve conduction, and evoked potential studies, were all normal. Angiography was unremarkable, except for Accepted for publication August 30, 1994. Address correspondence and reprint requests to Edwin D. Dunteman, MD, MS, Pain Management Center, Department of Anesthesiology, Washington University School of Medicine, Box 8054, 660 South Euclid Ave., St. Louis, MO 63110.

MD University

School of Medicine,

questionable slightly tortuous anterior inferior cerebellar arteries. Craniotomy and microvascular trigeminal nerve decompression performed at an outside hospital produced a postoperative course complicated by prolonged ventilator dependence and ataxia that resolved gradually over several months, but no significant change in pain. On examination, this thin, somewhat anxious, female exhibited normal facial sensation and motor strength. With range of motion testing, the mandible deviated to the right with diminished opening to 2.5 cm. Mandibular protraction, retraction, and left lateral excursion were all limited. The temporomandibular joint was nontender, without crepitations or clicks. Trigger points (TrPs) with the associated tenderness and pain referral were noted in the left masseter, temporalis, and medial and lateral pterygoids via intraoral palpation. Injections (0.5-l mL 1% lidocaine) to the involved TrPs produced immediate onset of complete relief for the first time in approximately 5 yr. After 20 h, the patient noted return of a more tolerable occasional ache (4/10) in the left maxillary gum. She reported improved hearing on the left, with resolution of sinusitis and sore throat symptoms for eight days. Dental consultation revealed improper-fitting partialplates with abnormal occlusion, amenable to minimal adjustments and splinting. Over the subsequent 6 wk, she required TrP injections on three occasions, followed by masticatory physical therapy. Pain-free periods after each set of injections lengthened progressively, with fewer active TrPs. Mandibular range of motion improved to allow mouth opening to greater than 4 cm. Opioids and anticonvulsants were discontinued without difficulty. Three months after therapy, the patient reported only occasional mild aches in the maxillary gum. Nasal discharge, sore throat, and auditory symptoms remained resolved. Eight months after therapy, the patient finally sought treatment for depression, although she had refused prior referrals for psychologic evaluation during the initial multidisciplinary pain evaluation and therapy.

Discussion MPD is rarely described in the general medical literature. As exemplified by this patient, it often 01994

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by the International

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CASE

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Temporalis Muscle

Figure 1. Referral

Masseter

patterns of pain (stippled shading) arising from trigger points (indicated by X) in the masticatory muscles. As in other myofascial syndromes, the perceived pain and tenderness is typically distant from the involved muscle site. Diagrams modified from Travel1 JG, Simons DG. Myofascial pain and dysfunction. The trigger point manual. Vol. 1. Baltimore: Williams and Wilkins, 1983, with permission.

Muscle

Medial

(Internal)

Pterygoid

Muscle

Lateral

(External)

Pterygoid

Muscle

presents as a diagnostic enigma, leading to misdiagnosis and use of ineffective therapies. Myofascial pain typically arises from an area known as a trigger point: a hyperirritable spot, usually within a taut band of skeletal muscle or fascia, that is painful on compression and gives rise to characteristic tenderness, referred pain, and autonomic phenomena (4). TrPs arise from cycles of sustained sarcomere contractions, increased metabolic activity, ischemia, and impaired excitation contraction coupling. Nociceptor sensitization and sarcomere contractures are maintained by the local release of substances such as lactate, bradykinin, prostaglandin E,, Substance I’, and potassium and hydrogen ions (7-9). The pain associated with TrPs in different muscles has specific referral patterns. The distribution of pain, usually distant from the actual TrP, is attributed to centrally mediated neuronal receptive field changes that complicate clinical diagnosis, especially when multiple muscles are involved (4,7).

Figure 1 demonstrates the complexity of TrP referral patterns. Autonomic phenomena “triggered” by TrPs may further complicate diagnosis. Masseter TrPs with pain referred to the ear may also cause tinnitus and vertigo. Lateral pterygoid TrP referral to the maxillary sinus, with reflex autonomic-induced excessive secretions, may mimic sinusitis. Lateral pterygoid TrPs may entrap the buccal nerve to cause numbness or burning pain in the cheek. Medial pterygoid TrPs may inhibit adjacent tensor-veli palatini openings of the eustachian tube and simulate otitis with ear stuffiness (barohypoacusis) and pain (4). Myofascial pain in other muscles, such as the sternocleidomastoid, trapezius, digastric, and other cervical and facial muscle groups, may be referred to the head and face, further complicating the clinical presentation (3,4). It is not uncommon for MPD to be misdiagnosed as trigeminal neuralgia when pain appears in trigeminal nerve distributions (1,3). However, patients with trigeminal neuralgia do not typically exhibit masticatory

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TrPs unless the problems coexist. Several medications and neuroablative or decompressive procedures may effectively treat trigeminal neuralgia, but unfortunately are ineffective in MPD (1). MPD etiologies have long been controversial. Proposed causes include occlusal (10-121, muscular (2,13-15), and psychcophysiologic (5,14-17) dysfunction. Occlusal contact point changes from dental losses, wear, or restorations change the bite to produce “occlusal disharmony.” Abnormal tension in masticatory muscles leads to formation of TrPs (6,11,12). Moreover, muscular injury may lead to spasm and TrPs that alter occlusion to incorporate additional muscles into the MPD (12,14). Common anxiety-related behaviors, such as bruxism and teethgrinding produce prolonged masticatory tension to promote myofascial dysfunction (14,15,17,18). Therefore, MPD may be attributed to several interrelated factors that obscure the distinctions between cause and effect. When possible, perpetuating factors should be treated at the same time as the active TrPs (3,4,13,15). Probable contributing etiologies in this patient include extensive dental restorations, poorly fitting dentures, and underlying depression. In chronic atypical facial pain, it is important to evaluate for TrPs, as it is treatable with minimally intrusive therapies. When found, MPD often responds to physical therapy, dental splints, accurately placed TrP injections, and nonopioid analgesics. Appropriate diagnosis is essential for successful therapy of MPD, which may avoid trials of unnecessary, unsuccessful, and/or invasive therapies.

References 1. McDonald JS, Pensak ML, Phero JC. Part I: Differential diagnosis of chronic facial, head, and neck pain conditions. Am J Otolaryngol 1990;11:299-303.

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2. Reynolds MD. Myofascial trigger point syndromes in the practice of rheumatology. Arch I’hys Med Rehabil 1981;62:111-14. 3. Travel1 J. Identification of myofascial trigger point syndromes: a case of atypical facial neuralgia. Arch Phys Med Rehabil 1981; 62:100-6. 4. Travel1 JG, Simons DG. Myofascial pain and dysfunction. The trigger point manual. Vol. 1. Baltimore: Williams and Wilkins 1983;165-272. 5. Ingle J. “The great impostor” [letter]. JAMA 1976;236:1846. 6. Morgan DH. The great impostor: diseases of the temporomandibular joint [letter]. JAMA 1976;235:2395. 7. Mense S. Nociception from skeletal muscle in relation to clinical muscle pain. Pain 1993;54:241-289. 8. Simons DG, Travel1 J. Myofascial trigger points: a possible explanation. Pain 1981;10:106-9. 9. Simons DG. Myofascial pain syndrome due to trigger points. In: Goodgold J, ed. Rehabilitation Medicine. Chapter 45. St Louis: Mosby. 1988:686-723. 10. Cooper BC, Alleva M, Cooper DL, Lucente FE. Myofascial pain dysfunction: analysis of 476 patients. Laryngoscope 1986;96: 1099-106. 11. Kampe T, Hannerz. Five-year longitudinal study of adolescents with intact and restored dentitions: signs and symptoms of temporomandibular dysfunction and functional recordings. J Oral Rehabil 1991;18:387-98. 12. Loiselle RJ. Relation of occlusion to temporomandibular joint dysfunction: the prosthodontic viewpoint. J Am Dent Assoc 1969;79:145-6. 13. Mackley RJ. The role of trigger points in the management of head, neck, and face pain. Funct Orthod 1990;7:4-14. 14. Lashkin DM. Etiology of pain-dysfunction syndrome. J Am Dent Assoc 1969;79:147-53. 15. Peterson AL, Dixon DC, Talcott GW, Kelleher WJ: Habit reversal treatment of temporomandibular disorders: a pilot investigation. J Behav Ther Exp Psychiat 1993;24:49-55. 16. Lupton DE. Psychological aspects of temporomandibular joint dysfunction. J Am Dent Assoc 1969;79:131-6. 17. Fricton J. Behavioral and psychsocial factors in chronic craniofacial pain. Anesth Prog 1985;32:7-12. 18. Fricton JR. Recent advances in orofacial pain and temporomandibular disorders. IASP Newsletter, 1993;July-August:2-5.