Value of paraspinal muscle myography in diagnosing L5 radiculopathy

Introduction. Electromyography (EMG) is an important diagnostic tool for the evaluation of radiculopathy. Since 1990s a paraspinal mapping technique is used, which detects spontaneous activity in paraspinal muscles (PM) at the level of several vertebral segments. This modality seems to be highly conclusive for diagnosing radicular lesions. The main limitation of this method is spontaneous activity dependence on the disease duration. The aim of the study is to assess if PM EMG with motor unit potential (MUP) analysis is conclusive for diagnosing lumbar radiculopathy. Materials and methods. The study examined 58 patients (26 men and 32 women) aged 2673 years with MRI-confirmed symptomatic L5 mono-radiculopathy due to L4L5 herniated discs. The study assessed the neurological status and needle EMG of m. tensor fasciae latae (TFL) and PM at L4L5 and L3L4 levels on both symptomatic and healthy sides immediately before radicular microscopic decompression surgery. Surgery outcomes were evaluated by early and late postoperative questioning. Results. In PMs of the affected level and side, the average MUP duration was significantly different from opposite MUPs at the higher segment (р 0.001). At 3-month disease duration, a neurogenic pattern was significantly more frequent in affected PMs (p = 0.031) with neurogenic PM MUP rearrangement in 73.3% of patients. In the TFL (L5), neurogenic changes were reported only in 47.4% of patients. When compared to normal values, significant differences were found in the average duration of TFL MUPs (р = 0.001) and PM MUPs of the affected level and side (р 0.001) both in patients with motor disorders and those with isolated pain syndrome or sensory disorders. Conclusions. For diagnosing radiculopathy, the sensitivity of needle PM EMG is 82.6% (48/58; 95% CI 70.691.4%). Compared to limb myotome assessment, the highest informative value of PM EMG was reported in patients with the disease duration for up to 3 months. PM EMG was conclusive for diagnosing radicular lesions in patients with isolated pain syndrome or sensory disorders.