Hypothenar Hammer syndrome in a young Australian male: A case report

Abstract

Hypothenar hammer syndrome (HHS) is a rare form of digital ischemia of the hand with occupational and recreational aetiologies. The condition is typically seen in middle-aged males who work with power tools and use the hypothenar eminence as a hammer. Key imaging findings include ulnar artery occlusion with or without aneurysms affecting the dominant hand. However, presentation is young age is extremely uncommon. Here we present 1 case of hypothenar hammer syndrome in a 20-year-old and describe how it is probably related to Australian demographics.

Introduction

Hypothenar Hammer syndrome (HHS) is rare traumatic vascular disorder resulting from repetitive compression of the ulnar artery in the hand [1]. First described by Van Rosen [2], the syndrome is an occupational hazard for carpenters and mechanics but can also be caused by sporting activities such as cycling, golfing and tennis [3]. It is caused by the repetitive use of tools or sporting equipment and typically occurs in the dominant hand. Bilateral HHS is rare [4]. Clinically these patient present with variable digital symptoms. Cold intolerance is the most common recorded symptoms, followed by finger cyanosis, altered sensation, finger gangrene and in rare circumstances only a hypothenar mass. HHS is essentially a clinical diagnosis requiring high index of suspicion backing up by imaging diagnosis. Treatment depends on severity of symptoms, medical line preferred for subtle symptoms and surgical line for severe symptoms [5].

Case presentation

A 20-year-old male presented with numbness, pain and coldness in his right ring finger. The patient worked as a mechanic, and his symptoms were aggravated when using an electric drill. He was a nonsmoker and a social drinker.

Physical examination revealed that the tip of the ring finger was paler and colder to the touch compared with the other fingers. The ulnar side of the hand showed an obvious 2 × 2 cm swelling, which was mildly tender but had no other features. No gangrene was present. Patient vitals were unremarkable, with no difference in blood pressure between the right and left upper limbs. Allen’s test was positive to ulnar arterial compression. Working diagnosis was a simple ganglion and nonspecific nerve compression which is quite common in the clinical practice considering patient demographics. Hence Xray and ultrasound imaging of the affected hand was requested for assessment.

Radiographic examination showed nothing remarkable (see Fig. 1). Ultrasound examination showed a short-segment thrombosis of the ulnar artery, 25 mm in length, at the level of Guyon’s canal, corresponding to the swelling on the hand (see Fig. 2). The radial artery had normal triphasic flow. No ganglion was found. And ulnar nerve calibre at the cubital tunnel and median nerve calibre at the carpal tunnel were within normal limits. The radiologist gave a suspected diagnosis of HHS and suggested following up with computed tomography (CT) angiography.

Fig. 1.

Frontal and lateral projection radiograph of wrist showing no obvious abnormalities.

Fig. 2.

Ultrasound image of the wrist showing short-segment occlusion of the ulnar artery (arrows).

During a follow-up consultation to discuss the scan results, Allen’s test was again positive. No further blood tests were done as patient was young and did not have any history of bleeding or clotting disorders. Clinician also found no change in symptoms to an emotional response to suggest Raynaud phenomenon and patient denied any recreational drug use.

The physician referred the patient for CT angiography. The results showed a complete occlusion of the superficial palmar arch corresponding to the ultrasound-detected occlusion (see Fig. 3) and an occlusion of the digital artery of the ring finger (see Fig. 4), which was directly contributing to the patient’s symptoms. The deep palmar arch was complete (see Fig. 5 ), and collateral circulation was intact. A diagnosis of HHS was confirmed.

Fig. 3.

CT Contrast Enhanced arterial phase Coronal reconstructed image of right hand showing complete occlusion of superficial palmar arch (arrows).

Fig. 4.

CT Contrast Enhanced arterial phase Coronal reconstructed image of right hand showing occluded 3rd palmar digital artery supplying the radial segment of ring finger (green arrows).

Fig. 5.

CT Contrast Enhanced arterial phase Coronal image of right hand showing complete deep palmar arch with radial and ulnar artery (long arrows). Occluded segment of third palmar digital artery also appreciated (short arrows).

The patient was given a choice of medical or surgical management. Given that the discomfort was only mild, the patient chose medical management. Although the patient was scheduled to follow up with the physician in 6 months’ time to consider surgery if symptoms had worsened, the follow-up call from the reception team went unanswered.

Discussion

HHS is a vascular compression syndrome involving the ulnar artery [1]. Anatomically, the superficial branch of the ulnar artery is vulnerable to trauma after it emerges from Guyon’s canal. Repetitive use of the hypothenar eminence as a hammer can cause the artery to be crushed against the hook of the hamate [6]. Over time, this can lead to intimal damage, resulting in platelet aggregation and thrombosis. Subsequent embolisation leads to the occlusion of downstream digital arteries [7].

HHS is typically observed in adult males aged in their forties. According to case reports and literature reviews, the mean age of presentation is 44 years, with a range of 36-69 years [1,3,7]. To the best of the author’s knowledge, the 20-year-old patient in this case is the youngest to present with HHS. The reason for this early presentation is unclear; however, possible causes include the early use of power tools by Australians [8]. Judge et al. [8] found that Australians can sustain injuries from power tools as early as 16 years of age, with a mean age of 37 years for men and 41.7 years for women. In Australia, easy access to healthcare services and worker’s compensation motivates patients to seek early treatment. The availability of advanced diagnostic tools may also be a reason for such an early diagnosis.

Clinical features

The clinical features of HHS vary depending on the degree of blood vessel collateralization. Cold intolerance and digital ischemia are the most common presentations. paraesthesia, single-digit cyanosis, Raynaud’s phenomenon and swelling occur less commonly, while finger necrosis and gangrene are rare. While Allen’s test is usually positive, indicating digital ischemia, it is negative in 15% of cases. [9] The patient in this case had well-developed collateral blood vessels, thus did not develop necrosis or gangrene. As diagnosis is mainly clinical, other differential for the HHS should be ruled out before commencing definitive treatment. Raynaud’s phenomenon, vasculitis, drug use and ulnar neuropathy all produce similar symptoms [1].

Diagnosis

The first-line radiological assessment of HHS is a Doppler ultrasound, which requires the patient to lie still for a considerable amount of time. While a Doppler ultrasound can readily detect occlusions or aneurysms in the ulnar and radial arteries, it cannot detect them in digital arteries or the palmar arch because of their tiny caliber [6]. The absence of an aneurysm in this case may have been attributable to the short duration of symptoms and the patient’s young age, meaning a higher amount of arterial smooth muscle and a lack of intimal thickening [6].

CT angiography is a highly sensitive contrast method that can be used to visualize small blood vessels. Modern multidetector CT scanners can generate high-resolution, multiplanar images of digital arteries in slices as thin as 0.3 mm. CT subtraction Angiogram is the latest technique provides comparable results to Digital Subtraction Angiogram [6].

MR angiogram is also a sensitive test but is seldom available in all centers in addition demands considerable amount of time as compared to CT angiogram. MR angiogram is also vulnerable for motion artifacts as patients with HHS tend to have digital symptoms [6].

DSA angiogram is Gold Standard as diagnosis and treatment can be offered at the same sitting [3]. Doppler ultrasound and CT angiography were the diagnostic tools used for the patient in this case as these were readily available [9].

Differential diagnosis

Raynaud phenomenon, vasculitis, recreational drug usage, ulnar neuropathy all produces similar symptoms. Clinical findings of scleroderma, thoracic outlet syndrome and giant cell arthritis can also mimic HHS [10]. Platelet count and coagulation profile should be done in all as a baseline study to rule out any underlying coagulopathies.

Raynaud phenomenon produces classical aggravation and cessation of symptoms to an emotional stimulus [11]. Recreational drug use like cocaine, amphetamine and cannabis are known to cause vascular ischemia on intra-arterial injection. Cocaine is especially known to cause multivessel vasculitis on prolonged usage [12]. Ergot derivatives traditionally used in Migraine medications are also known to cause acute and chronic vascular ischemia [13]. Details of all prior medications and current or past usage of recreational drugs including visits to rehabilitation camps should be sought.

Scleroderma is a connective tissue disorder presents with digital symptoms but are more likely to be soft tissue calcifications and bony erosions and less often true vascular ischemia. Again, detailed history and plain radiography of hands should rule out any potential calcifications [11]. Thoracic outlet syndrome produces mostly neurological symptoms secondary to compression of brachial plexus and very rarely vascular ischemia alone. Detailed clinical examination coupled with CT angiogram of thoracic outlet can rule out thoracic outlet syndrome. Rare circumstance requires MR examination of brachial plexus as well [14].

Management

HHS can be managed through lifestyle, medical or surgical interventions. Lifestyle changes include smoking cessation and avoidance of aggravating occupational or recreational activities [15]. Medical management includes low-dose aspirin and calcium channel blockers such as nifedipine [15]. Surgical management is recommended when there is a nonhealing ulcer of the finger, digital ischemia or gangrene and includes arterial resection and end-to-end anastomosis with a vein graft [16]. Interventional radiological treatments such as percutaneous thrombosuction and intra-arterial thrombolysis have also been successful [17].

Conclusion

HHS is a treatable cause of digital ischemia. The presentation of HHS in a young Australian male is possibly related to Australian demographics. The early diagnosis and management of the condition is crucial to prevent complications of digital ischaemia. CT angiography is the diagnostic modality of choice because it is universally available. The management of HHS can be either medical or surgical. Symptoms can also be mitigated through behavioral modification, smoking cessation and hand protection.

Patient consent

A written informed consent was obtained from the patient for this publication of case report titled as below.