Hypothenar Hammer Syndrome

                                   Dr. KS Dhillon

Introduction

Hypothenar Hammer Syndrome (HHS) is a rare condition. In this condition, there is ulnar artery insufficiency that is caused by repetitive blunt trauma to the hypothenar region of the hand. HHS was first described by Von Rosen in 1934 [1,2]. HHS is prevalent among middle-aged men who engage in jobs that result in the frequent use of the hypothenar region of the hand to pound or squeeze hard objects. This would include construction workers, auto mechanics, and miners [3]. HHS is also seen in patients who have overexposure to the use of vibratory tools and machinery, as well as in athletes from sports where trauma to the palm is common [4].

Patients can present with tenderness at the hypothenar region, unilateral

Raynaud’s phenomenon, pain and discoloration of the digits, most commonly the 4th and 5th digits. There can be increased sensitivity to cold in the affected hand. Symptoms are usually episodic. In severe cases, ulceration and necrosis can result in gangrene of the fingers [5]. In some cases, HHS may be misdiagnosed as musculoskeletal overuse. An increased awareness is necessary for early intervention before ischemic changes become irreversible [6]. 

Incidence

A large cohort study prospectively enrolled 1300 patients and they found that 21 patients had HHS giving an incidence of 1.6% [7]. HHS is widely regarded as a rare condition [7,8,9] and this may be because cases are asymptomatic.

Little and Ferguson [10] examined 79 workers who were habitual hypothenar hammerers and they found 14% of them had objective evidence of occlusion. However, none of them had symptoms of sufficient severity to interfere with their work activities. A physician survey was conducted that supported the fact that this syndrome is under diagnosed [11].

HHS is an occupational disease that is seen in a number of industries in which the workers use their hands to pound or to push. This includes carpenters [12], motor mechanics, metal workers, and lathe operators.  HHS is also seen in mountain bikers [13] and many other sports including baseball, volleyball [1], badminton [14], tennis [15], handball, softball, karate, weight lifting, and hockey [11].

HHS is also seen in individuals exposed to vibration in mining, forestry

and other industries [4,16].

Pathophysiology

A single or repetitive blunt impact on hypothenar eminence leads to ulnar artery thrombosis or aneurysm. The hook of the hamate functions as an anvil, causing thrombosis. Distal embolization leads to ulceration and gangrene.

Anatomy

The ulnar artery branches into 2 branches as it exits Guyon's canal. The 

deep branch and the superficial palmar arch in Guyon's canal. Over the distal 2cm, the artery is directly anterior to the hook of the hamate and is covered by the palmaris brevis, subcutaneous tissue, and skin.

Diagnosis

Patients with HHS can present with unilateral Raynaud’s phenomenon, tenderness on the hypothenar region, pain and discoloration of the digits, most commonly the 4th and 5th digits, and increased sensitivity to cold in the affected hand. Symptoms are usually episodic, and may or may not be precipitated immediately by trauma. In severe cases, ulceration and necrosis can result in gangrene of the digits.

HHS is often incorrectly diagnosed [17], or diagnosed at a late stage when irreversible damage has already taken place. The differential diagnosis of upper extremity digital ischemia includes primary Raynaud’s disease, Raynaud’s phenomenon associated with underlying connective tissue disorder, buerger’s disease, vasculitis, arterial emboli from a cardiac source, atherosclerosis with secondary thrombosis, thoracic outlet obstruction and hypothenar hammer syndrome [11,12].

The HHS presentation may initially be confused with that of Raynaud’s phenomenon. Therefore other causes of Raynaud’s phenomenon, such as systemic lupus erythematosus, scleroderma, or rheumatic disease should be excluded.

Spencer-Green et al [18] summarised the distinguishing manifestations of HHS from classic Raynaud’s phenomenon (Table 1).

Table 1. HHS; distinction from classic Raynaud’s phenomenon18

- Male preponderance.

- Occupational history of repetitive hand and wrist trauma.

- Asymmetric distribution.

- Absence of the hyperaemic phase.

- Diminished ulnar/radial pulses.

- Digital ulcers in areas supplied by affected vessel.

Pineda et al [19] has stated that although pallor and cyanosis may appear,

it is notable that hyperaemic redness was absent in patients with HHS.

Allen’s test can be useful in the diagnosis of HSS. Kaji et al [4], however, found it to be negative in 17% of their cases. Doppler examination can be useful in the diagnosis of HSS [1]. Taute et al [20] found that colour duplex sonography enabled distinction between HHS and other causes of digital ischemia. Arteriography is the gold standard test, which will differentiate HHS from other vascular abnormalities in the hand [1,11,12,21]. It is mandatory for the diagnosis of HHS. The angiogram will show a tortuous "corkscrew" ulnar artery with occlusion or aneurysm at the hook of the hamate.

HHS usually affects the medial 3 fingers that are mainly supplied by the superficial palmar arch, while the lateral 2 digits are unlikely to be affected as the deep palmar arch is complete in 97% of the HHS cases [21]. It is highly likely that HHS might present in a similar pattern to that of Hand-Arm vibration syndrome or with Raynaud’s like symptoms. The absence of typical hyperaemic flush in HHS is of distinguishing value along with a positive Allen’s test [1].

Treatment

Nonoperative

Conservative treatment of HHS includes lifestyle modifications, symptomatic treatment, and vascular consultation. The indications for conservative treatment include thrombosis without aneurysm of more than 2 weeks, absences of symptoms, and when there is no threat of digital loss. 

Conservative treatment includes cessation of the offending activity and the avoidance of exacerbating factors [21,22]. Smoking cessation is essential [1,23], low-lipid diet is also important, and repeated venesections to reduce smoking induced polycythemia has also been advocated [1,24].

Anti-platelet therapy should also be considered [21] and intravenous heparin and prostaglandin E1 may be useful [1]. Vasodilators, such as calcium channel blockers and cervical sympathectomy may also be helpful. Cervical sympathectomy may not be beneficial if the collateral vessels are already maximally vasodilated [21]. With conservative treatment, there is an 80% success rate.

Operative treatment

Endovascular fibrinolysis can be carried out if there is thrombosis without aneurysm of less than 2 weeks. 

Excision of involved segment and reconstruction with or without a vein graft         

can be carried out when the digital brachial index is less than 0.7, there is 

thrombosis with aneurysm, ischemia in multiple digits, and when conservative treatment fails and there are recurrent symptoms.

Arterial ligation (Leriche procedure) can be carried out when the digital brachial index is more than 0.7.

Conclusion

HHS is not as rare as it has been thought to be [1,25]. It is a preventable and curable cause of upper limb digital ischemia [11]. Sometimes patients may not volunteer a history of occupational or recreational trauma. Hence it is important that such history is carefully obtained. Investigations should be conducted before irreversible complications occur.

References

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2. On Rosen S. Ein Fall von Thrombose in der Arteria ulnarix nach Einwirkung von stumpfer Gewalt. Acta Chir Scand 1934;73: 500e506.

3. Conn J Jr, Bergan JJ, Bell JL. Hand ischemia: hypothenar hammer syndrome. Proc Inst Med Chic 1970;28:83.

4. Kaji H, Honma H, Usui M, et al. Hypothenar hammer syndrome in workers occupationally exposed to vibrating tools. J Hand Surg Br 1993;18(6):761-6.

5. Ablett CT, Hackett LA. Hypothenar hammer syndrome: case reports and brief review. Clin Med Res 2008;6:3-8.

6. Gardiner GA, Tan A. Repetitive Blunt Trauma and Arterial Injury in the Hand. Cardiovasc Intervent Radiol 2017.

7. Erris Bl, Taylor Jr Lm, Oyama K, Mcalafferty Rb, Edwards Jm, Moneta Gl et al. Hypothenar hammer syndrome: proposed etiology. J Vasc Surg 2000 Jan;31(1 Pt 1):104e113.

8. An De Walle PM, Moll Fl, De Smet Aa. The hypothenar hammer syndrome: update and literature review. Acta Chir Belg 1998 Jun;98(3):116e119.

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10. Little Jm, Ferguson Da. The incidence of the hypothenar hammer syndrome. Arch Surg 1972 Nov;105(5):684e685.

11. Wernick R, Smith Dl. Bilateral hypothenar hammer syndrome: an unusual and preventable cause of digital ischemia. Am J Emerg Med 1989 May;7(3):302e306.

12. Van De Walle PM, Moll Fl, De Smet Aa. The hypothenar hammer syndrome: update and literature review. Acta Chir Belg 1998 Jun;98(3):116e119.

13. Applegate Ke, spiegel Pk. Ulnar artery occlusion in mountain bikers. J Sports Med Phys Fitness 1995 Sep;35(3): 232e234.

14. Koga Y, Seki T, caro LD. Hypothenar hammer syndrome in a young female badminton player. A case report. Am J Sports Med 1993 NoveDec;21(6):890e892.

15. Noel B, Hayoz D. A tennis player with hand claudication. Vasa 2000 May;29(2):151e153.

16. Onn Jr J, Bergan JJ, Bell Jl. Hypothenar hammer syndrome: posttraumatic digital ischemia. Surgery 1970 Dec;68(6):1122e1128. 

17. Iskutin J, Dorffner R, Resinger M, Silberbauer K, Mostbeck G. Hypothenar hammer syndrome. Eur Radiol 2000; 10(3):542.

18. Spencer-Green, Morgan Gj, Brown L, Fitzgerald O. Hypothenar hammer syndrome: an occupational cause of Raynaud’s phenomenon. J Rheumatol 1987 Oct;14(5):1048e1051.

19. Pineda Cj, Weisman Mh, Bookstein Jj, Saltzsein Sl. Hypothenar hammer syndrome. Form of reversible Raynaud’s phenomenon. Am J Med 1985 Nov;79(5):561e570.

20. Taute Bm, Behrmann C, Cappeller Wa, Podhaisky H. Ultrasound image of the hypothenar hammer syndrome. Ultraschall Med 1998 Oct;19(5):220e224.

21. Tsavellas G, huang A, Ranaboldo Cj. Soft-tissue case 42. Hypothenar hammer syndrome. Can J Surg 2001 Dec;44(6):409, 466e467.

22. Mclafferty Rb, Edwards Jm, Taylor Jr Lm, Porter Jm. Diagnosis and long-term clinical outcome in patients diagnosed with hand ischemia. J Vasc Surg 1995 Oct;22(4):361e367.

23. Pittel Pc, Spittell Ja. Occlusive arterial disease of the hand due to repetitive blunt trauma: a review with illustrative cases. Int J Cardiol 1993 Mar;38(3):281e292.

24. Wieczorek I, Farber A, alexander K. Hypothenar hammer syndrome successfully managed with intravenous prostaglandin E1 and heparin and with correction of the thrombogenic risk profile. A case report. Angiology 1996 Nov;47(11):1111- 1116.

25. Gaylis H, Kushlick Ar. The hypothenar hammer syndrome. S Afr Med J 1976 Jan 31;50(5):125e127.