Differential diagnosis and conservative treatment for piriformis syndrome: a review of the literature

Comparing radial extracorporeal shockwave therapy and corticosteroid injection in the treatment of piriformis syndrome: A randomized clinical trial

OBJECTIVE

This study was designed to compare the effects of shockwave therapy and corticosteroid injection in the treatment of piriformis syndrome.

METHODS AND MATERIALS

In this randomized clinical trial, thirty-five patients with piriformis syndrome were randomly divided into two groups of 18 in the shockwave group and 17 in the corticosteroid group. The Shockwave group underwent three sessions of shockwave therapy per week (2000 pulses per session with 5Hz frequency and pressure equal to 4 Bar) and the corticosteroid group underwent an injection of 40 mg methylprednisolone with 1 mL of 1% lidocaine under ultrasound guidance. All patients were assessed by SF-36 questionnaire and visual analogue scale (VAS). The SF-36 questionnaire was used to evaluate the quality of life before and 4 weeks after the intervention. VAS scale was used to evaluate pain before the intervention, and 1, 4, 8, and 12 weeks after the intervention.

RESULTS

The baseline characteristics of the two groups were not significantly different. At the end of the study, both groups had a significant improvement in pain and quality of life compared to before the intervention. However, according to the VAS, in the shockwave group improvement was seen in the first follow-up while not seen in the corticosteroid group (P-value <0.001 and P-value 1.00, respectively). According to the SF-36 questionnaire, the overall score in both groups had a significant improvement (P-value <0.05).

CONCLUSIONS

It seems that shockwave therapy and corticosteroid injection are both effective in the treatment of piriformis syndrome. There was no significant difference between the two groups in the quarterly follow-up. Because shockwave therapy is a relatively non-invasive treatment with fewer side effects, it can be useful to improve pain and the quality of life of patients with piriformis syndrome.

Evaluation of Accuracy of Shear Wave Elastography and Superb Microvascular Imaging Methods in Diagnosis of Piriformis Syndrome: A Preliminary Study

Piriformis syndrome is a neuromuscular disease resulting from sciatic nerve compression caused by an abnormal condition in the piriformis muscle. Superb microvascular imaging (SMI) is a new ultrasound imaging technique that visualizes low-velocity and small-diameter blood vessel flow. In our prospectively designed study, we aimed to evaluate the accuracy of diagnosis of piriformis syndrome with innovative methods such as shear wave elastography (SWE) and SMI. Thirty-two patients diagnosed with unilateral piriformis syndrome were accepted to the statistical stage. The side without symptoms was considered the "unaffected side." Bilateral piriformis muscles were examined by ultrasonography. Muscle thickness was determined on gray scale, stiffness on SWE and vascularity characteristics on power Doppler and SMI by two independent radiologists. Piriformis muscle stiffness on the non-pathological (unaffected) side was measured by SWE as 18.27 ± 7.301 kPa, and the mean stiffness on the pathological side was 29.70 ± 10.095 kPa. Pathological side muscle stiffness was significantly higher (p < 0.05). Using innovative methods such as SWE and SMI in addition to conventional ultrasonography as much as possible in our daily practice and research helps us in making the correct diagnosis in piriformis syndrome.

[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.

The clinical features of the piriformis syndrome: a systematic review

Piriformis syndrome, sciatica caused by compression of the sciatic nerve by the piriformis muscle, has been described for over 70 years; yet, it remains controversial. The literature consists mainly of case series and narrative reviews. The objectives of the study were: first, to make the best use of existing evidence to estimate the frequencies of clinical features in patients reported to have PS; second, to identify future research questions. A systematic review was conducted of any study type that reported extractable data relevant to diagnosis. The search included all studies up to 1 March 2008 in four databases: AMED, CINAHL, Embase and Medline. Screening, data extraction and analysis were all performed independently by two reviewers. A total of 55 studies were included: 51 individual and 3 aggregated data studies, and 1 combined study. The most common features found were: buttock pain, external tenderness over the greater sciatic notch, aggravation of the pain through sitting and augmentation of the pain with manoeuvres that increase piriformis muscle tension. Future research could start with comparing the frequencies of these features in sciatica patients with and without disc herniation or spinal stenosis.