Negative Angiography Does Not Exclude Ulnar Artery Aneurysm in Hypothenar Hammer Syndrome.

Hypothenar hammer syndrome (HHS) is a vascular injury from repetitive trauma to the hypothenar eminence, causing ulnar artery damage. Symptoms include digital pain and paresthesia and can progress to ulceration or necrosis. We report the case of a 54-year-old man with episodic pain and discoloration in the left middle, ring, and little digits not exacerbated by activity. His history included alcohol use disorder and frequent bicycle use. Imaging demonstrated reduced ulnar artery flow without aneurysm, and diagnostic angiography revealed mild tortuosity. Doppler examination revealed softer arterial signals at the ulnar-sided digits. Despite nondiagnostic imaging, his clinical picture supported a diagnosis of HHS. After conservative management failed, surgical exploration revealed a 1-cm ulnar artery aneurysmal dilation along a 2.2-mm nondiseased segment, requiring resection and repair with end-to-end anastomosis. This case underscores that HHS cannot be reliably excluded by imaging alone and highlights the importance of clinical judgment in diagnosis and management.