Internal jugular vein entrapment in a multiple sclerosis patient.

We describe a multiple sclerosis patient presenting with compression of the internal jugular vein caused by aberrant omohyoid muscle. Previously this patient underwent balloon angioplasty of the same internal jugular vein. Ten months after this endovascular procedure, Doppler sonography revealed totally collapsed middle part of the treated vein with no outflow detected. Still, the vein widened and the flow was restored when the patient's mouth opened. Thus, the abnormality was likely to be caused by muscular compression. Surgical exploration confirmed that an atypical omohyoid muscle was squeezing the vein. Consequently, pathological muscle was transected. Sonographic control three weeks after surgical procedure revealed a decompressed vein with fully restored venous outflow. Although such a muscular compression can be successfully managed surgically, future research has to establish its clinical relevance.