Hypothenar hammer syndrome

May 25, 2007
Surgical Rounds®, October 2006, Volume 0, Issue 0

Mojtaba Gashti, Attending Vascular Surgeon, Department of Vascular Surgery, Union Memorial Hospital, Baltimore, MD

Mojtaba Gashti, DO Attending Vascular Surgeon

Department of Vascular Surgery

Union Memorial Hospital

Baltimore, MD

Hypothenar hammer syndrome is a rare condition that is caused by repeatedly using the base of the palm like a hammer, which damages the ulnar artery and may cause an aneurysm to form. Patients generally present with loss of sensation in the affected hand and painful digits that are cyanotic and sensitive to cold due to aneurysm thrombosis, embolization, or both. Although the condition can sometimes be treated medically, surgery may be required. The following case report is of symptomatic hypothenar hammer syndrome in a male patient who required surgery. A review of the literature is also provided.

Case report

A 68-year-old man came to the emergency department reporting acute pain in his left ring finger, which he had been experiencing for the previous 4 to 6 hours. The pain developed suddenly that morning while he was fishing and progressively worsened. He also lost sensation in that finger. Although he reported no traumatic injury, he stated, “I always use my hands as a hammer when in my boat.”

The patient was hypertensive and an ex-smoker. His surgical history was significant for coronary artery bypass graft surgery and aortic valve replacement in 1996. He had no history of myocardial infarction, cerebrovascular accident, transient ischemic attack, claudication, or previous hand and finger pain or discoloration. He was taking hydrochlorothiazide, atenolol, and warfarin.

On physical examination, the patient was in some distress because of the pain. His blood pressure was 162/94 mm Hg; his heart rate was 72 beats per minute and regular. Carotid pulses were present without carotid or subclavian bruits on auscultation. Palpable axillary, brachial, radial, and ulnar pulses were present bilaterally. The patient’s left ring finger had decreased sensation and was cold, cyanotic, and severely tender to passive range of motion exercises. There was a large, pulsatile, tender, and tense mass with a thrill in the left hypothenar area. His prothrombin time was 12.6 seconds with an international normalized ratio of 1.2. An electrocardiogram revealed normal sinus rhythm. A presumptive diagnosis of hypothenar hammer syndrome with thromboembolism of the distal ulnar and digital arteries was made, and the patient was brought to the operating room.

Under general anesthesia, a longitudinal skin incision was made over the pulsatile mass, and a 2.0 x 2.7-cm saccular ulnar artery aneurysm was discovered. Proximal and distal control was obtained with vessel loops. By this time, the aneurysm was no longer pulsatile and was excised. Although excellent inflow was noted, there was no back bleeding distally. A size 2 Fogarty catheter was passed distally, a large thrombus was removed, and brisk back bleeding was observed. An end-to-end anastomosis was preformed using size 7-0 polypropylene sutures in a running fashion. The artery exhibited an excellent pulse and the ischemic finger showed immediate improvement.

The patient was discharged to home on postoperative day 2, on his maintenance warfarin dose. At 14-month follow-up, there was a palpable pulse with no evidence of ischemia.

Discussion

In 1934, Von Rosen first described posttraumatic ulnar artery aneurysms and their resection.1 In 1970, Conn and associates used the term hypothenar hammer syndrome to describe finger ischemia caused by embolic occlusion of the digital arteries originating from the ulnar artery in a person who was repeatedly striking objects with the heel of the hand.2,3 Fewer than 100 cases of ulnar artery aneurysms have been reported in the literature and most are related to repetitive trauma.4 Intimal injury can lead to thrombosis or aneurysm formation. Von Rosen suggested that damage to the intima would result in thrombosis, whereas damage to the media would produce an aneurysm. Similar injuries have been reported in baseball, handball, and volleyball players.5-7 Patients are typically men, who present with acute onset of signs and symptoms related to digital ischemia.

Anatomy and pathophysiology

-The hand obtains its arterial supply through the ulnar and radial arteries (Figure). The ulnar artery and nerve pass through Guyon’s canal next to the hamate bone before dividing into the superficial and deep palmar branches. Just distal to the canal, a short segment of the superficial branch that forms the origin of the superficial palmar arch is unprotected between the skin and the bone in the hypothenar area. Chronic trauma to this area can lead to aneurysm formation in the ulnar artery.

The incidence of traumatic ulnar artery aneurysms is unknown because many individuals remain asymptomatic. People affected are frequently employed in the automotive or construction industries, where using pneumatic tools or repetitively striking objects with the dominant hand is characteristic of the syndrome. Ferris and colleagues studied the arteriography and histology in 21 patients with hypothenar hammer syndrome and concluded that this condition results from trauma to an artery in individuals with pre-existing fibromuscular dysplasia.3 Although patients with fibromuscular dysplasia are predominantly women, whereas hypothenar hammer syndrome is seen primarily in younger men, this theory may explain why the syndrome does not develop in most patients who experience repetitive palmar trauma. Little and Ferguson used Allen’s test and performed Doppler examinations on 79 workers who regularly used their hand as a hammer.8 They found only a 14% prevalence of subclinical ulnar artery occlusion.

Digital ischemia, pain, discoloration, and cold intolerance are the most common symptoms of hypothenar hammer syndrome. Aneurysm thrombosis may lead to arterial occlusion, but chronic embolization of the second through fifth digits is more common. In cold climates, this can produce symptoms of Raynaud syndrome. Discovery of an asymptomatic palmar mass or neuropathy from ulnar nerve compression are less common findings.

Diagnosis

-Hypothenar hammer syndrome is often readily evident based on the patient’s history and physical examination. A complete blood count, metabolic profile, sedimentation rate, autoimmune assays, and hypercoagulopathy profile should be obtained. Arterial Doppler examinations of the upper extremities are generally normal, but photoplethysmography of the index, long, and ring fingers reveals obstructive patterns in one or more digits. Catheter-based selective contrast angiography is the study of choice for four reasons: (1) to exclude the possibility of embolic events originating from the subclavian artery, such as atherosclerosis, aneurysm, or thoracic outlet syndrome; (2) to confirm the exact location of the vascular damage at the end of the ulnar artery; (3) to distinguish thrombosis from aneurysm; and (4) to evaluate embolic events in the digital arteries.9 Computed tomography angiography and magnetic resonance angiography could also be considered; however, the presence of digit-threatening ischemia may prohibit preoperative diagnostic studies.

Treatment

-Optimal treatment for hypothenar hammer syndrome has not been determined and remains a point of controversy mostly due to the rarity of the condition. Traditionally, this syndrome has been treated with observation, ligation and thoracic sympathetectomy, or aneurysm resection (with or without initial thrombolysis) with either primary anastomosis or interposition vein grafting.10,11 The goal of treatment is to reestablish flow to the palmar arch while eliminating the source of future embolization. Observation alone runs the risk of recurrent embolization and is generally not recommended. Ligation may result in worsening ischemia to the fourth and fifth digits if adequate collaterals are absent or occlusive disease exists in the radial artery. An Allen test should first be performed if one is considering this option, although these tests have an approximate 20% false-positive rate. Thrombolytic therapy before reconstruction may help improve the distal vascular perfusion.12

The advantages of resection and vascular reconstruction include removing the source of embolism and the painful mass and relieving ulnar nerve compression. If an interposition graft is required, a vein from the dorsum of the foot provides adequate caliber. Patients should be counseled regarding the need to avoid repetitive hand trauma; this may mean a change in occupation and ceasing smoking, which is a major risk factor for the development of arterial occlusive disease.

References

1. Von Rosen S. Ein Fall von thrombase in der Arteria Ulnaris nach einwirkung von stumpfer gewalt. Acta Chir Scand. 1934; 73: 500-506

2. Conn J Jr, Bergan JJ, Bell JL. Hypothenar hammer syndrome: posttraumatic digital ischemia. Surgery. 1970;68(6): 1122-1128.

3. Ferris BL, Taylor LM Jr, Oyama K, et al. Hypothenar hammer syndrome: proposed etiology. J Vasc Surg. 2000;31(1 pt1): 104-113.

4. May JW Jr, Grossman JA, Costas B. Cyanotic painful index and long fingers associated with an asymptomatic ulnar artery aneurysm: case report. J Hand Surg [Am]. 1982;7(6):622-625.

5. Lowrey CW, Chadwick RO, Waltman EN. Digital vessel trauma from repetitive impact in baseball catchers. J Hand Surg [Am]. 1976;1(3):236-238.

6. Buckhout BC, Warner MA. Digital perfusion of handball players. Effects of repeated ball impact on structures of the hand. Am J Sports Med. 1980;8(3):206-207.

7. Kostianen S, Orava S. Blunt injury of the radial and ulnar arteries in volley ball players. A report of three cases of the antebrachial-palmar hammer syndrome. Br J Sports Med. 1983;17(3): 172-176.

8. Little JM, Ferguson DA. The incidence of the hypothenar hammer syndrome. Arch Surg. 1972;105(5):684-685.

9. Vayssairat M, Debure C, Cormier JM, et al. Hypothenar hammer syndrome: seventeen cases with long-term follow-up. J Vasc Surg. 1987;5(6):838-843.

10. Nehler MR, Dalman RL, Harris EJ, et al. Upper extremity arterial bypass distal to the wrist. J Vasc Surg. 1992;16(4):633-642.

11. Mehlhoff TL, Wood MB. Ulnar artery thrombosis and the role of interposition vein grafting: patency with microsurgical technique. J Hand Surg [Am]. 1991;16(2):274-278.

12. Lawhorne TW Jr, Sanders RA. Ulnar artery aneurysm complicated by distal embolization: management with regional thrombolysis and resection. J Vasc Surg. 1986;3(4):663-665.