Despite this pre-procedural planning muscle biopsies can be non-diagnostic, due to a combination of the limited accuracy of intra-operative identification of viable muscle and the constraint of access to target muscles \cite{Joyce2012}. A retrospective review of 106 patients undergoing muscle biopsy demonstrated a diagnostic pathologic yield of 47% \cite{SO_2018}.
To complement the surgical technique, we have initiated an ultrasound-guided muscle biopsy service utilising a modified Bergström needle and vacuum technique. This allows the targeting of muscles previously not suitable for a surgical biopsy.
Aims and objectives
To retrospectively review the diagnostic accuracy and patient feedback outcomes of our ultrasound-guided muscle biopsy service that is utilised for the investigation of myopathy.
Methods and materials
At our muscle multidisciplinary team meeting (MDT), selected difficult cases of patients with undiagnosed myopathy where an open surgical biopsy was non-diagnostic or deemed too technically challenging, were discussed. If it was felt to be feasible by the musculoskeletal radiologist, a target muscle was identified on magnetic resonance imaging (MRI) and an ultrasound guided muscle biopsy was scheduled. A modified Bergström needle (Figure 2) and vacuum technique was performed under ultrasound guidance to better target a previously identified muscle (Figure 3).
After identifying the target muscle using ultrasound, local anaesthetic was infiltrated into the subcutaneous tissue and fascial plane. Facial perforation was then performed using a scalpel under direct sonographic guidance, to avoid any significant vascular structures and facilitate passage of the blunt tipped bergstrum needle into the muscle compartment.
The modified Bergström needle was then advanced to the target muscle under continuous sonographic guidance under high flow suction (Figure 4).
Once the needle was passed into the muscle, the stylet was retracted and 1-2 passes were performed. Each sample was placed in an universal container and sent for immediate histopathological analysis.
After the procedure each patient was observed whilst asked to lie on the site of biopsy for 2 hours. Once stable the patient was discharged.