HYPOTHENAR HAMMER SYNDROME Retrospective study of nine cases D. DE MONACO, E. FRITSCHE, G. RIGONI, S. SCHLUNKE and U. VON WARTBURG From the Department of Surgery, Section of Hand, Plastic and Reconstructive Surgery, Kantonsspital Lucerne, Lucerne, Switzerland
The hypothenar hammer syndrome is an uncommon lesion of the ulnar artery caused by repetitive trauma to the ulnar portion of the hand. It characteristically occurs in the dominant hand of middleaged craftsmen, but also in athletes practising various types of sports. We present a retrospective study of nine patients between 1988 and 1999. The follow-up ranged from 1 to 10 years. We recommend surgical treatment, by resection of the involved arterial segment and revascularization either by direct anastomosis or by means of a venous interpositional graft. Journal of Hand Surgery (British and European Volume, 1999) 24B: 6: 731±734 area the ulnar artery is trapped between a ``hammer'' (i.e. external trauma) and an ``anvil'' (i.e. the hamate bone), and may the traumatized by external mechanical stresses. The vascular lesions may vary, depending on the frequency and the severity of trauma, from simple arterial spasm, to thrombosis following an intimal lesion, or formation of an aneurysm if the damage occurs to the media (Fig 1). The clinical ®ndings may also take on various forms, such as symptoms of compression of the sensory branches of the ulnar nerve or arterial insuciency with ischaemic pain. In cases of large aneurysms it is not uncommon to ®nd only local tenderness on clinical examination.
In 1934 Von Rosen described a post-traumatic thrombosis of the ulnar artery adjacent to the hook of the hamate for the ®rst time. The typical history of repetitive trauma to the hypothenar region prompted Conn et al. (1970) to call this rare condition the ``hypothenar hammer syndrome''. The vulnerability of the ulnar artery over the hamate bone seems to be caused by an anatomical pecularity of the so-called space of Guyon: the ulnar artery, accompanying the sensory branch of the ulnar nerve passes around the hook of the hamate. At this point the artery and nerve are covered only by a ®ne layer of ®bres from the tendon of the ¯exor carpi ulnaris muscle, the palmaris brevis muscle, fat and skin. In this
Fig 1 (a) Intraoperative view of a thrombosed aneurysm of the ulnar artery. (b) Transection of the aneurysm. 731
PATIENTS AND METHODS Nine patients have been diagnosed and treated for this condition at the hospitals of Lucerne and Lugano from 1988 to 1999. The follow-up ranged between 1 and 10 years. There was a clear prevalence of men (8:1), with a mean age of 43 years (range, 25±82). Seven patients were smokers. In two cases the onset of symptoms could clearly be related to a single direct injury to the hypothenar area: one occurred in an 82-year-old woman after a distal fracture of the radius and one in a 29-yearold professional hockey-player after a violent slap shot.
THE JOURNAL OF HAND SURGERY VOL. 24B No. 6 DECEMBER 1999
All other patients reported repetitive blunt trauma in their work. The clinical ®ndings included (alone or in combination) irritation of the sensory branch of the ulnar nerve in ®ve patients, ischaemic symptoms in ®ve patients and local tenderness as a presenting feature in only two patients. Diagnosis was made by the typical history of blunt trauma to the hypothenar area, the clinical ®ndings (particularly a pathological Allen test) and selective angiography of the upper limb. The most common ®ndings were obstruction of the ulnar artery at the point where the vessel crossed the hamate, occlusion of digital
Fig 2 Arteriograms revealing: (a) occlusion of the ulnar artery at the level of Guyon's space and embolic occlusion of the digital arteries (arrows); (b) patent aneurysm of the ulnar artery.
HYPOTHENAR HAMMER SYNDROME
arteries, aneurysms, and the typical spiral deformation of the vessel (``corkskrew con®guration'') (Fig 2). We found nuclear magnetic resonance, duplex ultrasound (Fig 3) and thermography to be less useful because of their low sensitivity and diculties in their interpretation, although MRI aids in the detection of anatomical variants of the palmaris brevis muscle (MuÈller et al., 1997) and duplex ultrasound is helpful in assessing reperfusion after surgical reconstruction. RESULTS
Fig 2 (c) the typical ``corkscrew con®guration'', in an ulnar digital artery (arrowhead).
Two patients refused operative treatment and received oral platelet aggregation inhibitors and were told to avoid local trauma. After a follow-up period of 1 year, these patients still complained of the same symptoms and had unchanged clinical ®ndings. One patient suered from local tenderness and the other from recurrent painful ischaemic symptoms. Seven patients underwent surgical treatment by resection of the involved arterial segment, and reconstruction, either by means of direct anastomosis (six cases) or by a venous interpositional graft (one case). There were ®ve thrombosed aneurysms, one patent aneurysm and one isolated thrombosis. Analysis of the results according to the Given scale (Given et al., 1978) showed four excellent (no persistent symptoms) and three improved (persistence of one symptom). The most commonly observed persistent complaint was intolerance of exposure of the hand to low temperatures. Throughout the observation period, patency of the involved arterial segment was demonstrated by duplex ultrasound examination in all patients.
Fig 3 Ultrasound image demonstrating an aneurysm of the ulnar artery in the hypothenar region.
DISCUSSION These encouraging results lead us to recommend a surgical approach in the treatment of the hypothenar hammer syndrome. In view of the poor outcome in the two patients managed conservatively, we are convinced that resection of the involved arterial segment with subsequent reconstruction is the key to successful treatment with excellent long-term patency rates.
THE JOURNAL OF HAND SURGERY VOL. 24B No. 6 DECEMBER 1999 Given KS, Puckett CL, Kleinert HE (1978). Ulnar artery thrombosis. Plastic & Reconstructive Surgery, 61: 405±411. MuÈller LP, Kreitner KF, Seidl C et al. (1997). Traumatische Thrombose der distalen A. ulnaris (Hypothenar-Hammer-Syndrom) bei einem Golfspieler mit akzessorischer Muskelschlinge um den Guyonschen Kanal. Handchirurgie Mikrochirurgie Plastische Chirurgie, 29: 183±186. Von Rosen S (1934). Ein Fall von Thrombose in der Arteria ulnaris nach Einwirkung von stumpfer Gewalt. Acta Chirurgica Scandinavica, 73: 500±506.
Received: 17 March 1999 Accepted after revision: 18 May 1999 D. De Monaco MD, Department of Surgery, Section of Hand, Plastic and Reconstructive Surgery, Kantonsspital Luzern, 6006 Luzern, Switzerland.
Conn J, Bergan JJ, Bell JL (1970). Hypothenar hammer syndrome: posttraumatic digital ischemia. Surgery, 68: 1122±1128.
# 1999 The British Society for Surgery of the Hand Article no. jhsb.1999.0248