Piriformissyndrom infolge einer extragenitalen Endometriose

[The piriformis syndrome-a special indication for botulinum toxin]

The piriformis syndrome (PiS) is a possible cause of gluteal pain radiating into the legs. From a pathophysiological anatomical point of view a division into primary and secondary PiS is made. A primary PiS is based on variants of the course of the sciatic nerve with respect to the piriformis muscle. A secondary PiS occurs as a result of hypertrophy, tension and hardening of the piriformis muscle. Muscular hypertrophy causes an impingement syndrome with pressure on the sciatic nerve in the infrapiriform foramen more often than course variants. A tentative diagnosis of PiS can be made based on anamnestic information, clinical signs of strain and the flexion adduction internal rotation (FAIR) test. If asymmetry or hypertrophy exists, the tentative diagnosis is substantiated with the representation of the piriformis muscle in computed tomography (CT). Thus, a CT-supported botulinum injection (BTX) into the piriformis muscle is indicated. This is a pathogenetic treatment approach leading to a reduction in volume. In most cases a single treatment is sufficient. Since there are no adverse consequences, the BTX into the piriformis muscle is also justified from a diagnostic and therapeutic point of view in cases of primary PiS if the clinical indications are clear and other causes can be ruled out. In an in-house case series the tentative diagnosis of PiS could be made for 19 patients and the effectiveness of BTX was confirmed.

Piriformis muscle syndrome: A cross-sectional imaging study in 116 patients and evaluation of therapeutic outcome

OBJECTIVES

To increase the clinical awareness of piriformis muscle syndrome (PMs) by reporting cross-sectional imaging findings, the clinical impact of imaging studies and treatment outcome.

METHODS

Within a 10-year-period, 116 patients referred for radiological evaluation of clinically suspected PMs, with excluded lumbar pathology related to symptomatology, were prospectively studied with MRI and/or computed tomography (CT). Piriformis muscle (PM), sciatic nerve (SN), piriformis region and sacroiliac joints were evaluated. PMs was categorised into primary/secondary, according to a reported classification system. Treatment decisions were recorded. Outcome was categorised using a 3-point-scale.

RESULTS

Seventy-four patients (63.8%) exhibited pathologies related to PMs. Primary causes were detected in 12 and secondary in 62 patients. PM enlargement was found in 45.9% of patients, abnormal PM signal intensity/density in 40.5% and sciatic neuritis in 25.7%. Space-occupying lesions represented the most common related pathology. Treatment proved effective in 5/8 patients with primary and 34/51 patients with secondary PMs. In 34 patients, imaging revealed an unknown underlying medical condition and altered treatment planning.

CONCLUSIONS

Secondary PMs aetiologies appear to prevail. In suspected PMs, PM enlargement represented the most common imaging finding and space-occupying lesions the leading cause. Imaging had the potential to alter treatment decisions.

KEY POINTS

• In clinically suspected PMs cross-sectional imaging may reveal variable pathology. • Secondary PMs aetiologies appeared to be more common than primary. • PM enlargement represented the most common imaging finding in clinically suspected PMs. • Space-occupying lesions in the piriformis region represented the leading cause of PMs. • In clinically suspected PMs cross-sectional imaging may alter treatment planning.

Magnetic resonance imaging evidence for perineural spread of endometriosis to the lumbosacral plexus: report of 2 cases

Sciatic nerve endometriosis (EM) is a rare presentation of retroperitoneal EM. The authors present 2 cases of catamenial sciatica diagnosed as sciatic nerve EM. They propose that both cases can be explained by perineural spread of EM from the uterus to the sacral plexus along the pelvic autonomie nerves and then further distally to the sciatic nerve or proximally to the spinal nerves. This explanation is supported by MRI evidence in both cases. As a proof of concept, the authors retrieved and analyzed the original MRI studies of a case reported in the literature and found a similar pattern of spread. They believe that the imaging evidence of their institutional cases together with the outside case is a very compelling indication for perineural spread as a mechanism of EM of the nerve.

Cyclic sciatica from extrapelvic endometriosis affecting the sciatic nerve

Sciatic (catamenial) radiculopathy, waxing and waning with the menstrual cycle, is an uncommon condition typically caused by pelvic endometriosis affecting the lumbosacral plexus or proximal sciatic nerve. The authors describe a woman with catamenial sciatica caused by endometriosis affecting the sciatic nerve trunk in the upper thigh. Symptomatic with leg pain for 5 years, this patient developed gluteal atrophy and sensory loss and decreased strength in the L-5 dermatomyotome, a distribution confirmed by electromyography. Magnetic resonance imaging suggested thickening of the sciatic nerve at and distal to the sciatic notch. At operation the nerve showed extrinsic and intrinsic abnormality, proven to be endometriosis. Her symptoms improved, and she began gonadotropin-releasing hormone agonist therapy for further suppression. This very unusual case shows that endometriosis can affect the sciatic nerve over a range of territory inside and outside the pelvis, and that surgery must be appropriately directed to avoid negative exploration. Surgical decompression achieves good relief of symptoms, and medical therapy also allows sustained suppression of this disease.

Sciatic nerve compression related to ossification of the sacrospinous ligament secondary to pelvic balance abnomalities

The authors report an isolated case of right sacrospinous ligament ossification causing sciatic pain because of compression of the proximal sciatic nerve. The initial conservative treatment of injections in the conflict zone and the intervertebral joints was insufficient. Surgical exploration was undertaken via a posterior approach, demonstrating the conflict between the nerve and the ossified ligament. Resection of the ossified ligament eliminated the symptoms at the cost of transitory buttock hypesthesia. The anatomic and pathologic exam identified simple osseous metaplasia. Lumbar-pelvic coxometry analysis showed sagittalization of the acetabular roofs, excessive bilateral femoral torsion, and a step-off attenuation at the anterior cervicocephalic junction (low anterior cervico-cephalic femoral offset). In addition, reduced lumbar lordosis and accentuated sacral slope were noted, factors that could be related to modifications in the static balance of the lumbar-pelvic complex. This imbalance could be correlated to an increase in the forces applied to the pelvic ligament layers. The etiological hypothesis retained was that this osseous metaplasia was a reaction to excessive stresses on the sacrospinous ligament.