Recovery of Muscle Strength after Microdiscectomy for Lumbar Disk Herniation: A Prospective Cohort Study with 1-Year Follow-Up

Abstract

IntroductionIt has not been shown that surgery is better than nonsurgical management for treating limb paresis caused by lumbar disk herniation.1–3 However in clinical practice, limb paresis is a frequent additional symptom to pain4–6, and for the patients, a major concern remains: “What are the chances that my muscle strength will recover after surgery?”. The aim of this study is to give an answer to this question. We also wanted to investigate if persisting paresis is associated with worse outcome measured by changes in physical function, health related quality of life (HRQL), pain, and working capability.Materials and MethodsIn this prospective cohort study, we evaluated 403 consecutive patients operated with microdiscectomy for lumbar disk herniation. Of these patients, 91 (23%) had limb paresis and were included. All patients were operated at the Department of Neurosurgery, University Hospital of North Norway. Data were collected in a comprehensive clinical spine surgery registry for quality control and research between 1st of January 2004 and 30th of September 2006. Follow-up time from date of operation (baseline) was 1 year.The primary outcome measure was muscle strength of the affected limb. We used Daniels and Worthingham's techniques of manual muscle testing,7 which was graded to range from 0 to 5. Based on this scale we categorized the patients into three groups: severe paresis (grade 0–3), mild paresis (grade 4), and normal muscle strength (grade 5). Changes in motor function were classified as recovery (normal muscle strength) or nonrecovery (incompletely improved, unchanged or worse).Secondary outcome measures were HRQL (EQ-5D), Oswestry disability index (ODI), visual analogue scale (VAS) for leg pain and back pain, EQ-5D for general health state, and employment status.ResultsAt 12 months 68 patients (75%) were fully recovered. Out of 23 patients (25%) who were not fully recovered, 9 (10%) were improved and 14 (15%) were unchanged. None got worse. Out of 29, 16 (55%) patients with severe paresis fully recovered whereas 52 (84%) out of 62 patients with mild paresis fully recovered (p = 0.003). A severe paresis at baseline was the only independent risk factor we could find for not having full recovery of muscle function, odds ratio: 4.2 (95% CI, 1.6–11.4). Duration of the paresis was not associated with recovery. The mean (SD) duration of paresis was 30 (57) days.For the whole study population, there was a statistically significant improvement of pain, functional status, HRQL, and general health (p < 0.001). Patients who recovered had a significant better outcome than patients with persistent paresis, except for leg pain. Amongst those who did not recover, three times as many received workers compensation at 12 months follow up (57% vs. 20%, p = 0.001).ConclusionIn general, patients have a 75% chance of recovery from a limb paresis after surgical treatment for lumbar disk herniation. Patients with mild paresis can have a good chance to recover (84%). Patients with severe paresis have less good chance to recover (55%). Persisting paresis seems to have a significant negative impact on the physical function and HRQL. There was no association between the preoperative duration of the muscle weakness and recovery.I confirm having declared any potential conflict of interest for all authors listed on this abstractNoDisclosure of InterestNone declaredCribb GL, Jaffray DC, Cassar-Pullicino VN (2007) Observations on the natural history of massive lumbar disc herniation. Journal of Bone and Joint Surgery British Volume2007;89(6):782–784Dubourg G, Rozenberg S, Fautrel B et al. A pilot study on the recovery from paresis after lumbar disc herniation. Spine 2007;27(13):1426–1431Weber H. Lumbar disc herniation. A controlled, prospective study with ten years of observation. Spine 1983;8(2):131–140Eysel P, Rompe JD, Hopf C. Prognostic criteria of discogenic paresis. European Spine Journal 1994;3(4):214–218Mariconda M, Galasso O, Secondulfo V, Cozzolino A, Milano C. The functional relevance of neurological recovery after lumbar discectomy: a follow-up of more than 20 years. Journal of Bone and Joint Surgery British Volume 2008;90(5):622–628Postacchini F, Giannicola G, Cinotti G. Recovery of motor deficits after microdiscectomy for lumbar disc herniation. Journal of Bone and Joint Surgery British Volume 2002;84(7):1040–1045Hislop H, Montgomery J, H. Connolly B, Daniels L. Daniels and Worthingham's muscle testing: techniques of manual examination, 2007;Elsevier, 8th edn. 437