Muscle hernia involving the extensor carpi ulnaris muscle

Sir,

Muscle hernia (myofascial herniation) is an uncommon condition, in which focal protrusion of muscle occurs due to overlying fascia defect. Causes include congenital, trauma, chronic compartment syndrome and prior fasciotomy.[1,2] Although tibialis anterior is the most common muscle to herniate, other upper and lower limb muscles including extensor digitorum longus, peroneus longus and brevis, gastrocnemius and the forearm flexors may also herniate.[2,3] Overall, there have been about twenty cases of forearm muscle herniation in the literature,[4] with most of them involving the volar aspect.[5] Here, we present the first case of muscle hernia involving the extensor carpi ulnaris.

A 35-year-old male presented with a history of painless swelling in the dorsal aspect of the proximal forearm for 3 weeks. There was no difficulty or restriction of movements. The patient gave a history of lifting heavy loads of leather, for the last 3 months, but there was no acute injury/pain. There was a scar in the volar aspect of the proximal forearm, due to old cut injury. On clinical examination, the swelling was ovoid and well defined with normal overlying skin [FIgure 1a and b]. The lesion was best seen with the elbow in flexion and wrist in dorsiflexion. Plain radiograph showed a soft tissue swelling in the dorsal aspect of the forearm [Figure 1c]. A 1.5 Tesla magnetic resonance imaging (MRI) showed normal extensor carpi ulnaris muscle at the site of clinical swelling with posterior bulging of the muscle (it was more pronounced with dorsiflexed wrist) [Figure 2a–f]. As the patient had no symptoms except for the cosmetic deformity, he was reassured that it was only muscle hernia, and surgery was deferred presently.

Figure 1.

(a and b) Clinical photograph of the swelling of the dorsal aspect of the proximal forearm. (c) The plain radiograph of the forearm showing a subtle soft tissue swelling in the dorsal forearm on the lateral view

Figure 2.

(a-c) The dorsally herniating extensor carpi ulnaris muscle on axial T1, T2 and fat-saturated proton density weighted images, respectively. (d-f) The dorsally herniating extensor carpi ulnaris muscle on sagittal T1, T2 and fat-saturated proton density weighted images, respectively

Muscle hernias present as painless soft or firm swelling that may become visible/accentuated when the involved muscle is contracted. The swelling may sometimes become painful during exercise or strenuous activity because of entrapment and ischemia.[2] Primary reason for imaging is to rule out soft tissue neoplasm. Ultrasound and MRI have a role in imaging of myofascial herniations. Dynamic ultrasound examination performed during rest and stress may demonstrate focal thinning, elevation or disruption of the fascia covering the muscle with adjacent focal protrusion of muscle fibres in real time.[1] Conventional MRI may reveal the fascial defect sometimes only, as most patients are imaged at rest and the fascial covering is thin.[2] Asymptomatic patients can be managed only with reassurance. Surgical management usually needed for patients with pain includes fascial repair, fasciotomy or anatomical repair of fascial defect using autologous fascia/mesh.[3,4,5]

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