Abstract
Background:Piriformis Syndrome (PS) is an underdiagnosed cause of buttock, thigh and leg pain, most probably because it is thought to be a rare cause of sciatica. PS is widely believed to be myofascial in origin.Materials and Methods:This prospective, randomized, controlled, double-blind study was conducted at the pain management department. 50 patients aged from 20 to 60 years old were included in this study. The selected patients were randomly allocated into 2 groups containing 25 patients each; Group D received a total of 5 mL which included 2mL lidocaine 2%, 2mL (8 mg) dexamethasone and 1mL normal saline 0.9%, and Group M received a total of 5mL which included 2mL lidocaine 2%, 3mL magnesium sulphate (MgSO4) (2.5%) . Patients demographic characteristics, baseline physical examination findings of the patients as well as the duration of pain were all recorded. Patients were re-assessed immediately after injection, 1 week, 1 month, and 3 months after the injection. Numeric Rating Scale (NRS) values were used at each evaluation time to assess the pain, while patients were in sitting, standing, and lying positions. All patients were assessed immediately and for 4 hours post-injection for any side effects related to the drugs used.Results:In the pre-injection time, immediately after and 1 week after injection, there were no statistically significant differences between groups D and M in pain values. While, on comparison between both groups, group M, was significantly better than group D, in NRS values 1 month and 3 months after injection. In group D, pain score values were significantly better immediately, 1 week, and 1 month after injection compared to the pre-injection values, while these values were not significantly different 3 months after injection compared with the pre-injection values. In group M, pain score values were significantly better immediately, 1 week, 1 month, and 3 months after injection compared to the pre-injection values.Conclusion:Magnesium sulfate was more effective, especially for long term pain relief (3 months) when compared to dexamethasone as they were used as adjuvants to lidocaine, if injected into the piriformis muscle (PM) guided by ultrasound in the management of PS refractory as initial conservative treatment.
Highlights
The PM function is to rotate the hip joint externally when the thigh is extended and to abduct the flexed thigh
Management of Piriformis Syndrome (PS) starts with conservative pharmacotherapy using nonsteroidal antiinflammatory (NSAID) drugs, skeletal muscle relaxation drugs, and anti-neuropathic pain drugs in conjunction with physiotherapy, which emphasizes on stretching of the PM to treat the underlying pathology [5]
Injections were done at the peri-sciatic nerve site and the injectate was mainly local anesthetic plus steroids to treat the neuropathic pain resulting from the inflammation, edema, and the irritation of the sciatic nerve
Summary
The PM function is to rotate the hip joint externally when the thigh is extended and to abduct the flexed thigh. The sciatica and buttock pain that is initially due to trauma might cause inflammation, spasm, and hypertrophy of the muscle itself Inflammatory mediators, such as histamine, serotonin, prostaglandin, and bradykinin are released from the inflamed muscle and cause irritation of the underlying sciatic nerve leading to inflammation–irritation– spasm–pain cycle. Magnesium sulphate has no direct analgesic effect, it prevents calcium ions influx into the cells by blocking NMDA receptors post-synaptically, which leads to its anti-nociceptive effect, mainly in neuropathic pain conditions. This anti-nociceptive effect is believed to be due to its prevention of central sensitization produced by peripheral tissue damage.
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