Myofascial pain syndrome (MPS) is characterized by localized, taut regions comprising of skeletal muscle and fascia, termed trigger points and is an increasingly prevalent complaint. Pharmacologic interventions with evidence to support their use in MPS include muscle relaxants such as benzodiazepines, tizanidine, and cyclobenzaprine; TCAs; topical agents such as diclofenac gel and lidocaine patches; and injection therapy of botulinum toxin or lidocaine. MPS is poorly understood and remains a challenging condition to treat. Nonpharmacologic treatment modalities such as acupuncture, massage, transcutaneous electrical stimulation, and interferential current therapy may offer relief to some patients with MPS. Additional studies are warranted to get a better understanding of managing myofascial pain.

Chronic low back pain (CLPB) is one of the leading causes of physician office visits and work absenteeism in developed countries. Because many of the muscle groups involved in CLBP are easily accessible and respond well to injection, this disorder may be seen as particularly amenable to treatment with botulinum neurotoxin (BoNT). This chapter reviews the pathophysiology, diagnosis and treatment with BoNT of myofascial pain of muscles involved in lumbosciatic conditions (quadratus lumborum, iliopsoas and paravertebral). Physical examination of the patient is discussed and illustrated. Anatomy is reviewed, and anatomical diagrams are provided, along with discussion of guidance techniques, such as fluoroscopy, for the accurate placement and dosing of injections.