J.ONG1, A.THAM1, J.L.TAN1
Tan Tock Seng Hospital1
OMS is a condition that causes a X-shaped lateral neck lump on swallowing, caused by the failure of the central tendon of the omohyoid muscle to restrict movement of the muscle during swallowing. We aim to review the etiology, pathophysiology, diagnostic tests and management options for this condition.
Pubmed, MEDLINE, EMBASE and Cochrane databases were searched for all articles and abstracts related to OMS up to 29th July 2020. A systematic review was performed, data extracted from relevant full text articles. Both quantitative data and qualitative data were analysed.
20 cases of OMS were reported, with a mean age of 36.0. All cases were Asian. 70% were males. The most common symptom was a transient neck mass. Most cases were managed conservatively with good prognosis. Open or endoscopic transection of the muscle and ultrasound-guided botulinum toxin injection were three treatment options, with no recurrence at 4 years, 6 months and 6 months respectively.
OMS could be genetic as all reported cases occurred in Asians. The deep cervical fascia which usually envelopes the omohyoid muscle may be weakened by stress as 20% of cases had a preceding traumatic event. Real-time ultrasonography establishes the diagnosis, demonstrating the anterolateral displacement of the sternocleidomastoid muscle by a thickened omohyoid muscle during swallowing. Surgical transection can achieve cure, but they should be reserved for patients who are extremely bothered. Intramuscular injection of botulinum toxin is effective, but recurrence is expected.