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SALIVARY GLAND RED HERRINGS I - MASSETERIC HYPERTROPHY
Referrals to the Salivary Gland Center (SGC) include a high incidence of false positives- the red herrings, more about which will be heard in future issues. In the SGC, the most common entity mistaken for parotid enlargement is masseter muscle hypertrophy (MH). It is this muscleÌs proximity to the parotid gland that causes confusion.
The masseter, a thick quadrate masticatory muscle, arises from the zygomatic arch and inserts into the inferior lateral aspect and angle area of the mandibular ramus. MH is an asymptomatic persistent enlargement of one or both masseter muscles resulting from a work hypertrophy, initiated by clenching, bruxing, or heavy gum chewing. This occurs primarily in younger patients. In older age groups with dental deterioration, there is an inability to fully activate the masseters and any pre-existing MH tends to recede.
Anatomically, most of the masseteric thickness is along the inferior
portion of the mandibular ramus, where the facial contour normally
tapers. With MH, the patientÌs face takes on a characteristic
rectangular configuration (see illustration). Upon activation, the
previously flaccid muscle becomes firm and displays a discrete and
prominent outline. In addition, because of the increased muscle
bulk and tension, bony hyperplasia may be observed radiographically
in the area of the mu In contradistinction to MH, parotid swelling tends to accentuate facial ovality because the major portion of the gland is situated at a higher facial level adjacent to the ear. The parotid glands in MH are neither swollen nor tender. The salivary ducts are patent with a normal flow rate. Non-involvement of the parotids is further evidenced by normal sialochemical and sialographic findings.
Other than increased masseter muscle fibre length and diameter, histology reveals no abnormalities. Therefore, therapy is conservative and involves reassurance, muscle relaxants, psychiatric care, and dental bite plate construction. Surgery to reduce muscle mass is only indicated if cosmetic concerns become paramount. Botulinum toxin therapy has been suggested. It blocks neuromuscular conduction and leads to muscle atrophy. The Salivary Gland Center (SGC) was developed because a void existed in the diagnostic and comprehensive care of patients with salivary gland problems and/or secretory dysfunction. Since the diversity of these salivary conditions presents challenges to the clinician, the SGC is available for referrals. Louis Mandel, DDS Director, Salivary Gland Center (212) 305-9982
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insertion. Orally, tooth attrition resulting from bruxing or clenching
may be present.