Study on the Effects of Botulinum Toxin Type A on Back Muscle in Chronic Low Back Pain

Inclusion Criteria: * Suffering from muscular low back pain (between L-1 and S-1 level). * Symptoms of more than six months duration. * No benefit from previous treatments. * Patient must present with bilaterally more than 2 active trigger points (TrPs) in the region of the low back musculature. * CT scan or MRI examination of the lumbar spine was performed within the past year. * Absence of significant pathology, such as bone fracture, nerve damage or severe psychiatric condition. Exclusion Criteria: * Constant or persistent severe pain due to nerve root compression or fibromyalgia. * The patient has received surgery on the spine. * Other musculoskeletal disabilities e.g. myasthenia gravis, or disorders of the neuromuscular junction. * Any serious pathology, such as cancer, systemic inflammatory disease, vertebral fractures, neurological signs, spinal infection. * Epidural injection of local anaesthetics and steroids within 12 weeks proceeding inclusion. * Trigger point injection of local anaesthetics and steroid within 8 weeks proceeding inclusion. * Pain associated with urinary tract infections, or gynaecological disorders. * Bleeding disturbances or currently using coumarin derivatives.