CLINICAL PREDICTORS FOR OUTCOME OF TREATMENT OF LUMBAR HERNIATED NUCLEUS PALPOSUS

Abstract

Herniated nucleus palposus is a common and important cause of low back pain. Despite over 90% of the patients responding to conservative treatment, some patients still need operation. This study aimed to analyze the clinical predictors for the outcome of conservative treatment in herniated nucleus palposus. Two hundred and fifty-one patients who were diagnosed as lumbar herniated nucleus palposus and admitted to Prince of Songkla University during the period of 1995–2000 were included in the study. Patients who had absolute indications for surgery or had previous back surgery were excluded. Data were collected on demographic characteristics (age, sex, occupation, level of study, marital status), patient symptoms (including duration, characteristic and severity of pain) and result of physical examination (including result of straight leg raising test (SLRT), cross SLRT, motor power, sensory deficit and reflex). The mean age of the patients was 38 years and the mean duration of pain was 4.1 months. Eighty percent of the patients had positive SLRT and abnormal neurological function was found in 73%. One hundred and eighty-six patients underwent surgery owing to failure of conservative treatment. From multivariate logistic analysis, five independent factors affecting failure of conservative treatment of herniated nucleus palposus were pain intensity, duration of symptoms, positive cross SLRT, grade of muscle power and number of dermatome deficit. When constructing the parameters into a scoring system, we found that if the patient had a score less than 45, 80% of them respond to conservative treatment, in contrast to those who scored more than 65, the probability of conservative failure was 80%. This study implies that clinical predictors can be used for determining probability of conservative failure in herniated nucleus palposus.