Quadratus Femoris muscle causing deep gluteal syndrome: A rare cause of refractory sciatica of extraspinal origin in the presence of an anatomic variation

Article type: Case Report

Authors: Girolami, Marco^{a; *} | Tonetti, Laura^b | Pipola, Valerio^a | Rimondi, Eugenio^b | Albisinni, Ugo^b | Ricci, Alessandro^c | Gasbarrini, Alessandro^a

Affiliations: [a] Department of Oncologic and Degenerative Spine Surgery, IRCCS Rizzoli Orthopedic Institute, Bologna, Italy | [b] Department of Diagnostic and Interventional Radiology, IRCCS Rizzoli Orthopedic Institute, Bologna, Italy | [c] Department of Anesthesia-Resuscitation and Intensive Care, IRCCS Rizzoli Orthopedic Institute, Bologna, Italy

Correspondence: [*] Corresponding author: Marco Girolami, Department of Oncologic and Degenerative Spine Surgery, IRCCS Rizzoli Orthopedic Institute, Bologna, Italy. Tel.: +39 051 6366111; E-mail: [email protected].

Abstract: BACKGROUND: Sciatica of extraspinal origin represents both a diagnostic and a therapeutic challenge for spine specialists. Among these, quadratus femoris muscle (QF) is often overlooked as a pain-generator. REPORTED CASE: A 62-year old man was referred from general practitioner for isolated sciatica in the left leg, refractory to conservative treatments. Plain x-rays of the spine did not show any pathological finding nor did magnetic resonance imaging (MRI). MRI and CT showed QF with unusual morphologic features and agenesis of the contralateral QF. Ultrasonography-guided injection in the muscle was performed with mepivacaine and methylprednisolone obtaining relief of the symptoms. DISCUSSION: Leg pain can be very disabling and, when combined with a normal MRI of the spine, diagnosis can be tricky. Several causes of sciatica of extraspinal origin have been described, some of them originating from the so-called “deep gluteal space”. Anecdotal communications on anatomical variations of the quadratus femoris muscle are reported in literature. CONCLUSIONS: Differential diagnosis of sciatica of extraspinal origin must rule out sacroiliac and hip joint so as deep gluteal space structures. Among these, quadratus femoris muscle is often overlooked as a pain-generator. Ultrasonography-guided intramuscular injections and a program of stretching and strengthening exercises can achieve durable control on the symptoms.

Keywords: Low back pain, extraspinal sciatica, quadratus femoris, deep gluteal space, ultrasonography-guided injections

DOI: 10.3233/BMR-191523

Journal: Journal of Back and Musculoskeletal Rehabilitation, vol. 32, no. 4, pp. 667-670, 2019