Various types of sleep disturbance due to different sorts of low back pain: 5: A clinical database analysis

Abstract

Aim: To find out how, when, and why back pain causes sleep disturbance. This is the data analysis phase following a series of four literature reviews, which seek to find out whether different types of sleep disturbance can be caused by different sorts of back pain. Method: Discriminant analyses have been performed on 8 indices, 7 diagnoses, and 114 variables derived from a database of 88 clinical items collected prospectively from 1234 consultations for low back pain. Results: Difficulty getting off to sleep was essentially found to be an indication of back pain severity as shown by the correlations with PAIN index B (0.56), PAIN index A (0.47), pain visual analog scale (0.43), straight leg raising (SLR) ipselateral pain (0.40), SLR range (elevation −0.31), disability (ability −0.25), analgesic consumption yesterday (0.25), and the extent of pain down the leg (0.25). However, difficulty getting off to sleep showed some ‘non-severity’ aspects. It was seen relatively more in females; with direct lumbar trauma causing the first episode; and pain on resisted hip flexion. It was associated with less early morning stiffness in the back. Diagnostically it was a bit more indicative of the ‘anterior column’ symmetrical disc degeneration syndrome but also the ‘posterior column’ rotation back strain syndrome. Being awoken by back pain in the night also acted as a measure of back pain severity but not quite so effectively as difficulty getting off to sleep. Being awoken also seemed slightly more a ‘posterior column’ problem in the form of the facet joint syndrome, and slightly more so than rotation strain. Interestingly, being awoken was linked to asymmetry of the direction in which the feet pointed upwards when the patient was reclining. This observation probably reflects the relative degrees of rotation of opposite hips. This ‘foot’ aspect seemed equally linked to awakening with both pain turning and ache whilst remaining immobile. Awakening due to pain turning in bed was seen slightly more with the Facet joint syndrome. It was also linked more to being a male; with resisted hip internal rotation causing contralateral pain; with the sit up test inducing lopsided back pain; and lumbar extension standing causing unilateral pain. Awakening with ache or pain whilst immobile and remaining still was seen slightly more with S1 (and L5) prolapsed intervertebral disc (with nerve root deficit). It was also more common in females; and with resisted hip flexion painful; and lumbar flexion standing inducing bilateral back pain. Early morning stiffness in the back for an hour or more was seen more in the thoracolumbar junction level syndrome (which shows few signs in the low back). With regard to diurnal variation of back symptoms, the facet joint syndrome seemed worse in the mornings. Those worse in the afternoon, evening, or at the end of work were more often the older men; those that had the thoracolumbar syndrome who were also worse at night. Those worse at night had a sit up test that induced midline back pain; and standing lateral flexion caused less unilateral pain. This may just reflect the symmetrical disc degeneration syndrome. Discussion: All these finding will need to be replicated in further studies which could at the same time be used to explain the underlying mechanisms involved. Such understandings may well afford diagnostic insights and therapeutic benefits.