Sciatic hernia causing sciatica: MRI and MR neurography showing entrapment of sciatic nerve

Abstract

ABSTRACT. Sciatic hernia is a rare condition with diverse clinical manifestations. We report a case of sciatic hernia causing sciatica, in which the diagnosis made on CT was subsequently confirmed on MRI including magnetic resonance neurography. The salient clinical and imaging features and a brief review are presented. Sciatic hernia is a rare condition that can lead to bowel obstruction, sciatica, pelvic pain, back pain or ureteric obstruction [1,2]. Clinical diagnosis of this condition is difficult. Ultrasonography and CT are the imaging modalities commonly used to diagnose sciatic hernia, although MRI can be used in cases in which entrapment of the sciatic nerve is suspected. Magnetic resonance neurography (MRN) provides high-resolution images to demonstrate entrapment of the nerve and morphological changes in the nerve [3]. Colour Doppler can be useful in surgical planning, as it can provide information regarding bowel viability. Case reportA 55-year-old woman presented with swelling in the left gluteal region and pain in the left lower limb of two years' duration. A detailed clinical history also revealed that she had an abscess in the left gluteal region following an intramuscular injection one year previously; however, at presentation there was no clinical feature suggestive of abscess. Physical examination revealed non-tender soft swelling in the left lumbar region with associated atrophy of gluteal muscles. To diagnose the nature of the gluteal mass, a CT scan of the pelvis and gluteal region was performed. The CT scan revealed herniation of the sigmoid colon through the greater sciatic foramen reaching up to the skin surface and atrophy of the gluteal muscles. Other major pelvic organs including the uterus, ureter and urinary bladder were normally located ( Figure 1). As there was atrophy of the left gluteal muscles, and because the patient had symptoms of sciatica, entrapment of the sciatic nerve by sciatic hernia was suspected. MRI of the pelvis and upper thigh with MRN was performed to confirm entrapment of the sciatic nerve. MRN was used for high-resolution imaging of the sciatic nerve and was performed on a 1.5 T scanner (Sonata, Siemens, Erlangen, Germany) using a pelvis phase-array coil. Sequence parameters included 4 mm section thickness, 0 mm intersection gap, 18-24 cm field of view, 256 6 256 matrix, and an 8-to 10 min imaging time per sequence. The patient underwent axial T 1 weighted spin echo (580/11/2-3 [TR/TE/excitations]) and axial and oblique coronal short tau inversion recovery (STIR, 5000/27/2-3; inversion time, 130 ms) sequences. Coronal oblique images were taken parallel to the course of the sciatic nerve. MRI revealed thickening and increased signal in the left sciatic nerve on STIR coronal oblique images (Figure 2). Lateral deviation and entrapment of the nerve by hernia was also noted along with atrophy of the left gluteal muscles.

A giant retroperitoneal lipoma presenting as a sciatic hernia: MRI findings

“…It was first reported by Papen in 1750 (1). It is more common in adults and women (2,3). Sciatic hernia may present as a gluteal mass or with complications of the pelvis content (2)(3)(4).…”

“…It is more common in adults and women (2,3). Sciatic hernia may present as a gluteal mass or with complications of the pelvis content (2)(3)(4). This content may be small intestine (obstruction), ureter and bladder (infection and obstruction), ovaries and fallopian tubes (pelvic pain), colon, omentum and Meckel's diverticulum (1).…”

“…This content may be small intestine (obstruction), ureter and bladder (infection and obstruction), ovaries and fallopian tubes (pelvic pain), colon, omentum and Meckel's diverticulum (1). Sciatica occurs as a result of compression of the sciatic nerve by the herniated sac (1)(2)(3)(4)(5). To our knowledge, four well-documented descriptions of a lipoma herniating through the sciatic foramen have been reported, and it was first defined in 1964 (3, 4, 6, 7).…”

“…MRI is the modality of choice to evaluate the sciatic nerve in cases of sciatic hernia (2). Surgical treatment of the This mass was well-circumscribed, isointense with the subcutaneous fatty tissue (Fig.…”

“…It is generally determined by the symptoms related to herniated content such as bowel obstruction, pelvic pain, and ureteric obstruction. Sciatic hernias may present as a rare cause of sciatica (1)(2)(3)(4). Retroperitoneal neoplasm with sciatic hernia is considered the rarest, with a very limited number of published reports in the literature.…”