A Systematic Review of the Omohyoid Muscle Syndrome (OMS): Clinical Presentation, Diagnosis, and Treatment Options.

OBJECTIVE: Omohyoid muscle syndrome (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.

DATA SOURCES: Pubmed, MEDLINE, EMBASE, and Cochrane databases were searched for all articles and abstracts related to OMS up to 29th July 2020.

REVIEW METHODS: A systematic review was performed, data extracted from relevant full text articles. Both quantitative data and qualitative data were analyzed.

RESULTS: Twenty cases of OMS were reported. Patients presented at a mean age of 36.0. All cases were Asian. There is a 7:3 ratio of males to females. 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 3 treatment options, with no recurrence at 4 years, 6 months, and 6 months respectively.

CONCLUSION: OMS could be genetic as all cases were Asian in ethnicity. 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 due to limited studies available, they should be reserved for patients who are extremely bothered. Intramuscular injection of botulinum toxin is an effective alternative, but recurrence is expected.