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

Abstract

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.

Hypothenar hammer syndrome (HHS) is a vascular overuse injury caused by repetitive blunt trauma to the hypothenar eminence—often from using the palm as a “hammer”—which damages the ulnar artery as it passes through Guyon’s canal.^1,2 This trauma is typically occupational or sports-related and most often affects the dominant hand.³ Recurrent arterial injury can result in vasospasm, thrombosis, aneurysm formation, and microemboli, ultimately leading to digital ischemia.^4,5 Ulnar nerve compression may also occur, producing pain and paresthesias in the middle, ring, and little digits.⁶ Anatomic variations in palmar circulation, particularly the position of the ulnar artery relative to the hamate, may further predispose individuals to injury severity.² Clinically, HHS may present with digital ischemia, cold sensitivity, fingertip discoloration, Raynaud-like changes, or finger claudication; severe cases may progress to ulceration or gangrene.^3,5 Initial noninvasive evaluation includes the Allen test, Doppler mapping, plethysmography, and cold stress testing.² Angiography remains the definitive imaging modality, enabling visualization of arterial occlusion, aneurysm, thrombosis, or characteristic tortuosity.⁷

Angiographic findings such as ulnar artery aneurysm, tortuosity, occlusion near the hook of the hamate, and distal digital artery cutoffs are considered pathognomonic for HHS.^6,7 However, the absence of these features does not exclude the diagnosis when the clinical picture is strongly suggestive.

In this case, we describe an uncommon presentation of HHS in a 54-year-old man who presented with classic symptoms and risk factors of HHS; however, angiography findings only displayed ulnar artery tortuosity and digital artery cutoffs, without evidence of aneurysm. The fact that the aneurysm was not detected on the angiogram is particularly surprising and underscores the importance of relying on clinical suspicion alongside imaging, as a normal or nondiagnostic angiogram does not rule out HHS.

Case Report

Clinical presentation

A 54-year-old right-handed undomiciled male with a history of alcohol use disorder presented with episodic pain and cyanosis of the middle, ring, and small fingers of his left hand. Symptoms had progressed over 3 weeks, with pain worsening during each episode and improving with warming. He denied antecedent trauma but reported frequent manual labor and regular bicycle use. The patient had a history of occasional recreational marijuana smoking, but does not smoke tobacco or vape.

On evaluation by vascular surgery, radial and ulnar pulses were palpable. Computed tomographic angiography (CTA) demonstrated decreased ulnar artery flow with poor opacification distal to the wrist crease. A formal angiogram with possible intervention was pursued. The study showed mild ulnar artery tortuosity without aneurysm (Fig. 1A), an intact palmar arch, and abrupt distal cutoffs of the digital arteries supplying the affected fingers. No discrete lesions amenable to intervention were identified. A heparin infusion and aspirin therapy were initiated, and no endovascular intervention was performed.

Figure 1.

Patient presentation displayed A cyanosis of the middle, ring, and small fingers of the left hand during physical examination and B abrupt distal cutoffs to the digital arteries of those same fingers in diagnostic angiography (AP projection).

Hand surgery was then consulted. Examination revealed cyanosis and marked tenderness of the affected fingertips (Fig. 1B). Allen’s test demonstrated overall perfusion of the hand through both ulnar and radial arteries. Reperfusion was noted to be slower through the ulnar artery than through the radial artery. Cyanosis of the distal ulnar digits was stabilized with radial and ulnar artery perfusion. Doppler examination noted the presence of arterial signals to the base of the digits, although softer at the ulnar-sided digits. A Duplex ultrasound study was not performed. Warming provided partial symptomatic relief, whereas narcotics, multimodal analgesia, and topical nitroglycerin were ineffective. Despite the atypical absence of an aneurysm on angiography, his presentation was highly consistent with HHS, and operative exploration was recommended due to persistent ischemic pain.

Surgical technique

Intraoperatively, a 1-cm aneurysmal dilation of the ulnar artery was identified just distal to the pisiform (Fig. 2A, B). The diameter of the surrounding nondiseased ulnar artery segments was 2.2 mm. The lesion was excised, and primary end-to-end anastomosis was performed without bypass grafting under loupe magnification using interrupted 9-0 nylon sutures (Fig. 2C), successfully restoring arterial flow. The wrist was then immobilized in a dorsal blocking splint.

Figure 2.

A Aneurysmal dilation of the left ulnar artery, distal to the pisiform. B Excisedaneurysm. C End-to-end anastomosis without bypass graft of the excised area of the ulnar artery, allowing for re-establishment of blood flow.

Postoperative course

Postoperatively, the ulnar digits showed improved warmth and coloration, although mild cyanosis persisted initially. We suspect this to be secondary to residual distal thromboemboli originating from the aneurysm. The patient remained on a heparin infusion and was monitored for pain control. Alcohol withdrawal–related agitation was managed with a Clinical Institute Withdrawal Assessment for Alcohol protocol. By postoperative day 1, his pain had significantly improved. He left the hospital against medical advice on postoperative day 2. At 4-week follow-up, he reported complete resolution of pain and paresthesia, with warm, well-perfused digits and normal capillary refill. At 4 months postoperatively, the patient continued to demonstrate sustained resolution of ischemic symptoms (Fig. 3) and was able to use his hand without restriction. Written informed consent was obtained from the patient for publication of this case report and accompanying images.

Figure 3.

Patient is well-healed at 4 months postoperatively.

Discussion

As the ulnar artery enters the hand, a vulnerable segment lies between the deep palmar branch and the start of the superficial palmar arch. Repetitive blunt trauma to the hypothenar eminence can compress this segment against the hook of the hamate, causing intimal damage and subsequent thrombosis; deeper injury to the media can lead to aneurysm formation.^4,6

Embolization from thrombi within the aneurysm can produce a “shower” of microemboli that occlude distal digital arteries, leading to acute worsening of ischemia and pain characteristic of HHS.⁸ CTA remains the gold standard for diagnosing HHS.^2,7 Characteristic findings—including ulnar artery aneurysm, occlusion, or the classic corkscrew configuration—are considered pathognomonic when correlated with clinical symptoms.^1,2

Other diagnostic tools include the Allen test, which assesses superficial palmar arch patency but carries false-negative rates up to 14% in HHS and false-positive rates of 22%.⁶ Doppler mapping can further evaluate ulnar artery flow.^1,2 In our case, CTA demonstrated only reduced ulnar flow; however, the patient’s clinical history and occupational exposure maintained a high index of suspicion. Diagnostic angiography later revealed mild tortuosity. This highlights that HHS cannot be excluded on imaging alone and that clinical judgment should carry equal—if not greater—weight in guiding diagnosis and management.

Hypothenar hammer syndrome predominantly affects middle-aged men and occurs in the dominant hand in approximately 93% of cases.⁵ Occupations or sports involving repetitive hypothenar impact are strongly associated with the condition.2, 3, 4 Patients typically present with pain and paresthesia in the medial three digits supplied by the superficial palmar branch.^4,6 Symptoms range from cold sensitivity, pallor, or cyanosis to severe complications such as ischemic ulceration or gangrene.1, 2, 3^,5,6 Because it mimics Raynaud phenomenon, distinguishing features such as unilateral presentation and the absence of a hyperemic “red” phase are critical for diagnosis.^1,4,6

Hypothenar hammer syndrome incidence is likely underestimated due to underdiagnosis and misdiagnosis, although cohort studies estimate its incidence at approximately 1.6%.^1,2,4 In a study of 79 vehicle maintenance workers, 14% showed distal ulnar artery injury despite being undiagnosed and experiencing only mild ischemic symptoms.⁹ A separate study noted factory workers, masons, carpenters, and metal workers were most frequently affected, with an average of 21 years of occupational exposure.⁵ Although no universal treatment guideline exists, most studies support conservative management for mild cases and reserve surgery for severe occlusions or aneurysms (Yuen et al¹). Conservative measures—including smoking cessation, activity modification, protective gloves, calcium channel blockers, antiplatelet or anticoagulation therapy, pentoxifylline, and local wound care—are effective in approximately 83% of cases.^1,3 However, recurrence rates up to 27.7% have been reported.⁵ Surgical options include arterial ligation, resection with end-to-end repair, or reconstruction using grafts, particularly when multiple digital arteries are compromised, and collateral circulation is insufficient.^1,3

This case underscores that HHS cannot be reliably excluded by imaging findings alone and highlights the critical role of clinical judgment in both diagnosis and management. Although diagnostic angiography did not show a classic ulnar artery aneurysm, the patient’s constellation of symptoms combined with a history of repetitive manual labor was highly suggestive of HHS. This case emphasizes that a high index of clinical suspicion should guide operative decision making, rather than reliance on angiographic findings in isolation.

Conflicts of Interest

No benefits in any form have been received or will be received related directly to this article.