Venous Thoracic Outlet Syndrome Provoked by Sleeping Posture.

A 96-year-old female with severe dementia complained of subacute onset of right arm swelling after sleep using her right arm as a pillow. Computed tomography and ultrasonography could not detect any significant findings. Nevertheless, her unilateral edema was similar to that of a venous disorder; therefore, we performed angiography of the brachial vein with the right arm in a normal position and in an abduction position; significant stenosis was seen in the latter position. We diagnosed her with venous thoracic outlet syndrome. This case was unique from the typical cases of venous thoracic outlet syndrome because of the subacute onset of symptoms, high age at onset, and discrepancies between ultrasonography and angiography findings. Dementia is the key factor explaining these features. The diagnosis of thoracic outlet syndrome is generally difficult. Although provocative physical examination maneuvers and ultrasonography are essential, dynamic testing with provocative maneuvers allows physicians to detect venous compression, even if it is difficult to capture with static imaging tests. Once the diagnosis and its etiology were confirmed, corresponding intervention, including physical therapy, is warranted.