Purpose of study and background. Psychological factors are considered to play a role in development and maintenance of chronic low back pain (CLBP). Stress or anxiety can change pain sensitivity; however, this has predominantly been studied in healthy individuals with limited work in individuals with musculoskeletal pain. The objective of this study was to quantify the effect of acute exposure to a psychosocial stressor on mechanical pain sensitivity in individuals with and without CLBP. Summary of methods and results. Six individuals with CLBP and 10 individuals without CLBP performed a 10-minute computer task under conditions of low and high psychosocial stress. Psychosocial stress was manipulated using mental maths and memory tasks combined with social evaluative threat. The effect of the stressor was evaluated using blood pressure, heart rate and the state anxiety component of the Spielberger State-Trait Anxiety Index. Mechanical pressure pain threshold (PPT) was recorded on the tibialis anterior muscle using a handheld digital pressure algometer. The stress manipulation increased self-reported anxiety (p<0.001), but not blood pressure or heart rate (p>0.06). Change in PPT from low to high stress was greater in the CLBP group (median ΔPPT = −0.5 kg/cm. 2. ) than in the control group (−0.15 kg/cm. 2. ; p=0.005). Conclusion. Individuals experienced an increase in pain sensitivity after acute exposure to a stressor designed to mimic low-level workplace stressors, and this increase was greater in individuals with CLBP than asymptomatic individuals. These results indicate that this experimental model can be used to study links between pain sensitivity and psychosocial stressors and increase our understanding of their potential role in CLBP. Conflicts of Interest: No conflicts of interest. Sources of funding: No funding obtained

Introduction. Changes in the central nervous system (CNS) pathways controlling trunk and leg muscles in patients with low back pain and radiculopathy have been observed and this study investigated whether surgery impacts upon these changes. Methods. Parameters of corticospinal control were examined on 3 occasions in 22 patients prior to, at 6 and 26 weeks following lumbar decompression surgery and in 14 control subjects at the same intervals. Electromyographic activity was recorded from tibialis anterior (TA), soleus (SOL), rectus abdominis (RA), external oblique (EO) and erector spinae (ES) muscles at the T12 & L4 levels in response to transcranial magnetic stimulation of the motor cortex. Results. In the surgical group, asymmetries in the size of motor evoked potentials (MEPs) in TA (P=0.001) and in the cortical silent periods (cSP) were found between the left and right sides in SOL (P=0.005) and ES at L4 (P=0.014) prior to surgery. This was not observed at 6 or 26 weeks. Abdominal responses could be evoked in 12 patients and there was a significant reduction in the cSP contralateral to the pain in EO (P=0.034) and RA (P=0.041) at 6 weeks. These parameters remained stable in controls over time. Discussion. The fact that changes appear to stabilise at 6 weeks is of interest as this parallels clinical outcome studies. Current work is ongoing to examine these excitability changes in both inhibitory and excitatory cortical pathways in these patients, and to what extent they may be related to clinical outcome

We have studied, prospectively, 116 patients with motor deficits associated with herniation of a lumbar disc who underwent microdiscectomy. They were studied during the first six months and at a mean of 6.4 years after surgery. Before operation, muscle weakness was mild (grade 4) in 67% of patients, severe (grade 3) in 21% and very severe (grade 2 or 1) in 12%. The muscle which most frequently had severe or very severe weakness was extensor hallucis longus, followed in order by triceps surae, extensor digitorum communis, tibialis anterior, and others. At the latest follow-up examination, 76% of patients had complete recovery of strength. Persistent weakness was found in 16% of patients who had had a mild preoperative deficit and in 39% of those with severe or very severe weakness. Muscle strength was graded 4 in all patients with persistent weakness, except for four with a very severe preoperative deficit affecting the L5 or S1 nerve root. They showed no significant recovery. Excluding this last group, the degree of recovery of motor function was inversely related to the preoperative severity and duration of muscle weakness. The patients’ subjective functional capacity was not directly related to the degree of recovery except in those with persistent severe or very severe deficit

Spinal stenosis and disc herniation are the two most frequent causes of lumbosacral nerve root compression. This can result in muscle weakness and present with or without pain. The difficulty when managing patients with these conditions is knowing when surgery is better than non-operative treatment: the evidence is controversial. Younger patients with a lesser degree of weakness for a shorter period of time have been shown to respond better to surgical treatment than older patients with greater weakness for longer. However, they also constitute a group that fares better without surgery. The main indication for surgical treatment in the management of patients with lumbosacral nerve root compression should be pain rather than weakness.

There have been a few reports of patients with a combination of lumbar and thoracic spinal stenosis. We describe six patients who suffered unexpected acute neurological deterioration at a mean of 7.8 days (6 to 10) after lumbar decompressive surgery. Five had progressive weakness and one had recurrent pain in the lower limbs. There was incomplete recovery following subsequent thoracic decompressive surgery.

The neurological presentation can be confusing. Patients with compressive myelopathy due to lower thoracic lesions, especially epiconus lesions (T10 to T12/L1 disc level), present with similar symptoms to those with lumbar radiculopathy or cauda equina lesions. Despite the rarity of this condition we advise that patients who undergo lumbar decompressive surgery for stenosis should have sagittal whole spine MRI studies pre-operatively to exclude proximal neurological compression.

Cite this article: Bone Joint J 2013;95-B:1388–91.