|Sciatica: Studies of symptoms, genetic factors, and treatment with periradicular infiltration|
Sciatic pain is classified as radicular pain – pain radiating from the back into the dermatome of the affected nerve root along the femoral or sciatic nerve trunk, or as nonradicular pain – pain radiating in the leg in a nondermatomal pattern (van Akkerveeken 1996). True radiculopathy is defined as radicular pain in the presence of a neurological deficit (Bogduk 1997a).
Various surveys have found the prevalence of sciatic pain in the adult population to be between 1 and 40 % (Frymoyer 1991). The prevalence of lumbar disc syndrome (herniated disc or typical sciatica) was studied as part of the Mini-Finland Health Survey (Heliövaara et al. 1987a). A diagnosis of lumbar disc syndrome was made for 5.1% of the men and 3.7% of the women aged 30 years or over. In a Finnish longitudinal cohort study, symptomatic lumbar disc disease (herniated nucleus pulposus (HNP) or sciatica) appeared around the age of 15 years, and the incidence rose more sharply from the age of 19 (Zitting et al. 1998). In Finland, the prevalence of age-adjusted work disability in sciatica has been reported to be over 14 % (Heliövaara et al. 1989). In 1999, compensation was paid for almost 600 000 days of sick leave because of some ICD-10 M51-diagnosis (e.g. radiculopathy M51.1, and disc displacement M51.2, but not low back pain M54.5). According to the National Insurance Register, the reimbursement cost of these sick leaves was FIM 112 million ($22 million) in 1999.
Surgery is traditionally regarded as the only effective treatment for sciatica (Mixter & Barr 1934, Weber 1983). Knowledge of the pathophysiology of sciatica has, however, increased greatly during the last decade. It was observed that disc herniations are common in asymptomatics (Boden et al. 1990, Jensen et al. 1994), and that disc ruptures without a herniation can induce similar sciatic symptoms to HNP (Ohnmeiss et al. 1997, Ohnmeiss et al. 1999). The concept of inflammation underlying sciatica was presented (McCarron et al. 1987, Olmarker et al. 1993, Olmarker et al. 1995, Saal 1995). Furthermore, the genetic background of sciatica is also being resolved (Annunen et al. 1999, Paassilta et al. 2001).
In this thesis, the study population consisted of consecutive sciatic patients. Patients were thoroughly examined clinically and by MRI in order to describe the determinants of sciatic symptoms and signs, and the phenotypes of the different Trp alleles of collagen IX. Patients were randomized to receive periradicular infiltration with either a combination of steroid and anaesthetic, or saline. Theoretically, in view of the inflammatory concept, steroid treatment could be a cost-effective treatment option for sciatica.