ULTRASOUND EVALUATION OF MUSCLE HERNIA

ULTRASOUND EVALUATION OF MUSCLE HERNIA

Most muscle hernias occur in the lower leg and affect the tibialis anterior muscle , and are attributed to occupational and sporting activities, trauma , chronic compartment syndrome, and weakness in the overlying fascia due to perforating vessels. It is seen  as a result of muscle protrusion through a defect in the muscle  fascia into the subcutaneous fat and eventually seen as  an overlying bulging soft-tissue mass , making slight contour hump. The adolescents or young adults are affected more. Clinically a swelling is  seen that usually enlarges when the affected muscle is contracted or the patient is in  standing or erect posture , and reduces when the muscle is relaxed .  Mostly muscle  hernias are asymptomatic and requires no treatment . Those with mild symptoms that may be relieved by support stockings. Patients with severe pain or cramps may require surgery.

At USG -  1 ] Focal thinning and slight elevation of the fascia.

                2] Focal fascial defect with protrusion or bulge  of muscle fibres through the defect  when the muscle                     is contracted , and making a contour hump. [ fig 1,2] 

               3] Prominent arterial pulsation on color or power Doppler - support the theory that muscle herniation                        occurs at sites of weakness in which vessels penetrate the fascia [ fig 3] 

                                          Fig 1 - A 20 yrs young boy presented with a small swelling at mid part of right anterolateral leg , which becomes conspicuous & painful on exercise or on continuous walking .  Long US scan shows focal bulge in tibialis anterior muscle [ arrows] on muscle contraction or on standing 

                                           

                                          Fig 2 - Both LS & TS ultrasound scans of the same case  , shows a small focal defect in the Fascia of tibialis  anterior muscle [ arrow in TS scan ]  with focal muscle fibres bulge or contour hump [ arrow in LS scan ]

                              

                                            Fig 3 - TS & LS ultrasound with color doppler scans shows a prominent vessel , likely perforating artery , at the site of fascial defect & muscle bulge or hernia  

Most muscle hernias do not require any  treatment [  or requires just reassurance] , but some painful cases may needs surgery. Importantly ultrasound is very helpful in apprehensive patients to exclude muscle tears and tumors . 

PS – This presentation is intended for academic purpose esp. for medical professionals & radiologists

Ref - American Journal of Roentgenology. 2003;180: 395-399

      [Read More: http://www.ajronline.org/doi/full/10.2214/ajr.180.2.1800395]