Keywords
artery - ulnar - hypothenar - hammer
Introduction
Symptomatic ischemia of the upper extremity may indicate a wide variety of conditions,
including atherosclerosis, arterial embolism, vasculitis, diabetic arteriopathy, neurovascular
compression, Raynaud syndrome, sepsis, and arterial trauma.[1] Some of these etiologies are surgically correctable, and their early identification
avoids consequences.
Although rare, aneurysmal conditions of the ulnar artery are one of the most frequent
causes of digital ischemia. Guattani described the first case of hand aneurysm in
1772, but only in 1970 did Conn et al.[2] call it hypothenar hammer syndrome. This strange condition can be seen in people who use the palm of their hand to strike
repeatedly as if it were a hammer, hence this terminology. Its symptoms range according
to the size of the aneurysm and the instability of its contents. In the case herein
reported, the patient presented with a pulsating tumor with progressive increase and
pain in the wrist, with no other associated clinical symptoms.
Clinical Case
A 67-year-old retired male used to be an office worker. He was referred for consultation
due to an increase in the size of a pulsatile mass and pain in the ulnar region of
the left hand with progressive growth.
As far as history, it is worth noting that he had quit smoking nine years before and
had been carrying out renovation work in previous days with repetitive microtrauma
to the palmar aspect of the left hand.
The physical examination revealed palpated pulses at all levels. The patient had a
pulsating tumor in the hypothenar eminence of the left hand measuring 1 cm to 2 cm,
with elongation of the ulnar artery at the level of the wrist. He presented good perfusion
of the left hand, and the Allen test was positive.
An arterial Doppler ultrasound showed ulnar artery ectasia (measuring 13 mm) with
a mural thrombus occupying 80% of the arterial caliber. The test ruled out aneurysms
in other locations (aorta and femoropolyteal sector).
A magnetic resonance angiography study confirmed the presence of a saccular aneurysm
(measuring 13 mm x 9 mm) at the ulnar artery, patent, and a small band of luminal
thrombosis in its distal wall with good distal flow ([Figures 1] and [2]). The test also revealed important signs of rhizarthrosis and nodules compatible
with incipient Dupuytren disease in the palmar region of the third and fourth fingers.
Fig. 1 Coronal magnetic resonance angiography section at the level of the hypothenar eminence
revealing a patent ulnar artery saccular aneurysm.
Fig. 2 Axial section of a magnetic resonance angiography at the level of the hypothenar
eminence showing an ulnar aneurysm.
We indicated surgery due to the abundant mural thrombus resulting in a high risk of
distal embolization and digital necrosis and the symptoms (pain and functional disability).
We also requested venous mapping with Doppler ultrasound of the left upper limb in
case the arterial reconstruction required grafts.
Under locoregional anesthesia, we performed a zigzag incision, dissection, and control
of the ulnar artery proximal and distal to the aneurysm, followed by aneurysm resection
and end-to-end anastomosis, without tensioning the ulnar artery, since arterial elongation
did not require the interposition of a venous graft ([Figures 3], [4] and [5]).
Fig. 3 A 13-mm ulnar artery aneurysm, proximal (yellow vessel loop) and distal (blue vessel
loop) controls of the aneurysm sac.
Fig. 4 End-to-end arterial anastomosis after aneurysm excision.
Fig. 5 Ulnar artery with no tension after the end-to-end anastomosis.
Patient discharge occurred the day after surgery, with good perfusion of the left
hand, positive radial and ulnar pulses, and a negative Allen test ([Figure 6]).
Fig. 6 Outcome of the hand after surgery.
Months after the intervention, a Doppler ultrasound showed ulnar artery patency and
good hand perfusion. In addition, the patient was asymptomatic.
Discussion
Hypothenar hammer syndrome is a rare vascular injury, with less than 200 published
cases. Some authors consider it an occupational disease. It mainly affects men, in
a ratio of 9:1, with an average age of 40 years. Most patients are smokers, and the
disease affects the dominant hand in 75% of cases.[3] Patients who use the hypothenar eminence as a tool to deliver repeated blows have
a high risk of developing this condition, frequently seen in workers such as mechanics,
miners, machinists, and carpenters, for example. The condition has also been related
to self-limited traumatic events.[4] In the case herein presented, the patient reported repetitive microtrauma on the
palmar aspect of his dominant hand during renovation work. This condition can also
affect athletes who perform repeated manual actions, in activities such as karate,
handball, tennis, and golf, for example.[2]
[5]
The pathophysiology of hypothenar hammer syndrome is due to the anatomy of the ulnar
artery as it passes through Guyon canal. After penetrating the hand, the artery continues
superficial to the hypothenar muscles, and it is covered by the palmar brevis muscle,
the palmar aponeurosis, and the skin. In this area of just 2 cm, the artery extends
above the uncinate process of the hamate bone, which acts as a hammer and contributes
to its injury after prolonged and repetitive trauma. Mural degeneration with arterial
intima compromise causes thrombus formation, and arterial media injury may lead to
aneurysm formation.[6] Acute ischemia, atheroembolism, and neurological compression are the most frequent
complications. Some authors[7] have suggested that trauma is not the only cause of the syndrome, and fibrodysplasia
would be partially responsible for aneurysmal degeneration.
The symptoms usually begin insidiously and result from microembolizations of material
within the aneurysm sac. Most frequently, pain occurs at the second, third, fourth,
or fifth fingers of the affected hand, but paresthesia, numbness with hand paleness
and coldness, claudication, trophic lesions from digital ischemia, and changes in
the color of the fingers also appear. Our patient had pain in the hypothenar eminence
and a pulsating mass, leading to his referral to our clinics. In severe cases, ulcerations,
gangrene, or eschar formation may appear.[3]
[6] The unilateral symptoms and preservation of the thumb distinguish this condition
from the Raynaud phenomenon.
For diagnosis, it is essential to take a detailed clinical history and have a high
index of suspicion. Examination reveals coldness and distal digital atrophy; sometimes,
a pulsating tumor is palpated at the level of the hypothenar eminence. The physical
examination includes the Allen test to evaluate the patency of the superficial palmar
arch. A positive test indicates potential arterial occlusion, stenosis, or incomplete
development. Although it is not specific to this condition, an abnormal result in
the Allen test would warrant more tests in a patient with a risk history. Doppler
ultrasound is a first-line non-invasive diagnostic test to evaluate the ulnar artery
for potential blood flow abnormalities, but it is observer-dependent and requires
significant technical skill.[3]
[5]
[6] Angiography has been considered the gold standard for its diagnosis. This test can
identify the type and extent of the lesion, thus defining the vascular anatomy to
plan the surgical treatment. However, it does not show the thrombus, only the aortic
lumen. It is also invasive and not free of complications. Therefore, some authors[8] prefer non-invasive procedures, such as computed tomography angiography or magnetic
resonance angiography. These tests not only identify the vascular lesion but define
the associated bone and muscle anatomy.[3]
[5]
[6] In our patient, after clinical suspicion, we performed a Doppler ultrasound, which
revealed ulnar artery ectasia. Next, using magnetic resonance angiography, we completed
the study to plan a therapeutic approach.
Regarding management, there are no consensus guidelines on the best clinical practice.
The conservative medical treatment consists in quitting smoking, avoiding repeated
trauma, and the use of medications (calcium channel blockers, antiplatelets, anticoagulants,
or hemorheological agents). Surgical treatment relies on the permeability and integrity
of the palmar arch and the speed of the onset of symptoms; so, in an abrupt onset
or presence of poor vascular compensation and a patent aneurysm, resection and subsequent
arterial reconstruction are recommended.[9] On occasion, arterial reconstruction is necessary using a venous graft; alternatively,
ligation of both ends of the artery is feasible if the palmar arch is compensated.[10] In our patient, we interposed a venous graft and performed an end-to-end anastomosis
due to arterial elongation.
The prognosis of the syndrome is good, with satisfactory outcomes in all published
cases. The medical literature reports a single patient undergoing digital amputation
due to this disease.[2]
