Sciatic endometriosis presenting as periodic (catamenial) sciatic radiculopathy

Abstract

Many causes of traumatic sciatic neuropathy have been described in the literature [1], but extrapelvic endometriosis of the gluteal region presenting as sciatica remains difficult to recognize. Here, we present the case of a 45-year-old woman with a history of lower back pain and lower limb stiffness in whom hip MRI showed multiple loci of endometriosis localized in both iliac muscles and in the right gluteus. The woman presented with a 15-day history of lower back pain and impaired ambulation. Neurological examination showed lower limb stiffness with left leg flexure and right leg hyperextension, right foot dorsiflexion deficit, positive Lasegue sign, gait disturbance and severe pain with apparent (L4)-L5-S1 distribution. An EMG and a spinal cord MRI scan had previously been performed without any pathological findings. Intravenously administered myorelaxants and NSAIDs were tried without any benefit. Her past medical history was consistent only with diabetes. Routine blood tests showed only mild anaemia and high cancer antigen-125 (CA-125) levels. Brain and spinal cord MRI, backbone CT, and total-body PET scans did not show any pathological findings. Orthopaedic examination showed groin pain, irradiating to the knee and worsened by hip movement. On MRI T2-weighted images both the iliac and psoas muscles and the gluteus maximus and minimus appeared markedly bright. In the iliac muscles two T2-hyperintense formations, without contrast enhancement but with a hypervascular rim, were evident; the right gluteus showed similar findings (Fig. 1a). On the 4th day of hospitalization her period started and the patient reported worsening pain and severe abdominal cramps. Gynaecological examination showed a 2-cm fibrotic nodule in the pouch of Douglas, suggestive of endometriosis. CA-125 was 49.3 IU/ml (cutoff 35 IU/ml). A cycle of leuprorelin (a gonadotropinreleasing hormone agonist which downregulates the secretion of gonadotropin luteinizing hormone and folliclestimulating hormone leading to hypogonadism) was started, and thereafter symptoms slowly resolved. A follow-up MRI scan performed 3 months later showed a reduction in size and number of the lesions; neurological examination was normal (Fig. 1b). In accordance with previous report [1], CA-125 was elevated in our patient. The marked T2 brightness in both the iliac and gluteus muscles seen on the MRI scan was consistent with oedema and hyperaemia or, as described previously [2], neurogenic muscular injury. This finding may be suggestive of an endometriosic lesion localized at or near the sciatic notch. The T2-hypentense formations were consistent with foci of endometriosis localized in the muscle tissues. The cyclicity of the symptoms and their regression after a cycle of leuprorelin further supports our hypothesis [3, 4]. Endometriosis-induced cyclic sciatica was firstly reported by Schlincke in 1946 [5]. Since then, approximately 60 cases have been described. Lesions of the ipsilateral sciatic nerve are reported as the primary cause of almost all the endometriosis-induced cyclic sciatica [6]. The commonest localization is the sciatic notch where fibrosis, organized haematoma and endometrial tissue L. Ghezzi (&) A. Arighi A. M. Pietroboni F. Jacini G. G. Fumagalli N. Bresolin D. Galimberti E. Scarpini Department of Neurological Sciences, ‘‘Dino Ferrari’’ Center, Fondazione Ca Granda, IRCCS Ospedale Maggiore Policlinico, University of Milan, Milan, Italy e-mail: lauraghezzi@me.com