BACKGROUND: Aneurysms of the superficial temporal artery (STA) usually are pseudoaneurysms and occur after blunt or penetrating trauma to the head or after surgery in the temporal region. However, true aneurysms of the STA are very rare. This report describes the case of a true aneurysm of the STA that appeared after trauma and discusses several relevant studies about the development and mechanism of this aneurysm. METHODS: A 57-year-old woman was referred to the neurosurgery department due to a slowly growing mass on her left parietal scalp. She reported a history of trauma to the head 3 months before the consultation. However, examination showed the scar located far from pulsatile mass. Imaging studies showed a fusiform aneurysmal dilation of the parietal branch of the STA. The frontal branch likely was occluded due to the previous injury. RESULTS: Surgical removal was performed, and the proximal STA was ligated. Histologic examination showed all three layers of the arterial wall to be intact and only luminal dilation. No sign of atherosclerosis or inflammation was detected. CONCLUSION: The aneurysm in this case was a true aneurysm. The mechanism underlying the spontaneous development of this true aneurysm is not fully understood, although it is possible that insensible minor blunt trauma weakened the arterial wall or reduced the elasticity of the artery. Increased blood flow of the parietal branch due to occlusion of the frontal branch can facilitate aneurysmal dilation. It is speculated that the real incidence of traumatic true STA aneurysms has been underreported. Thus, the authors recommend histologic examination in all traumatic aneurysm cases. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.
BACKGROUND:Aneurysms of the superficial temporal artery (STA) usually are pseudoaneurysms and occur after blunt or penetrating trauma to the head or after surgery in the temporal region. However, true aneurysms of the STA are very rare. This report describes the case of a true aneurysm of the STA that appeared after trauma and discusses several relevant studies about the development and mechanism of this aneurysm. METHODS: A 57-year-old woman was referred to the neurosurgery department due to a slowly growing mass on her left parietal scalp. She reported a history of trauma to the head 3 months before the consultation. However, examination showed the scar located far from pulsatile mass. Imaging studies showed a fusiform aneurysmal dilation of the parietal branch of the STA. The frontal branch likely was occluded due to the previous injury. RESULTS: Surgical removal was performed, and the proximal STA was ligated. Histologic examination showed all three layers of the arterial wall to be intact and only luminal dilation. No sign of atherosclerosis or inflammation was detected. CONCLUSION: The aneurysm in this case was a true aneurysm. The mechanism underlying the spontaneous development of this true aneurysm is not fully understood, although it is possible that insensible minor blunt trauma weakened the arterial wall or reduced the elasticity of the artery. Increased blood flow of the parietal branch due to occlusion of the frontal branch can facilitate aneurysmal dilation. It is speculated that the real incidence of traumatic true STA aneurysms has been underreported. Thus, the authors recommend histologic examination in all traumatic aneurysm cases. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.