British Journal of Rheumatology 1992;31:389-394
RADIOGRAPHIC DEMONSTRATION OF PARASPINAL MUSCLE WASTING IN PATIENTS WITH CHRONIC LOW BACK PAIN BY R. G. COOPER, W. ST. CLAIR FORBES* AND M. I. V. JAYSON Rheumatic Diseases Centre, University of Manchester and 'Department of Neuroradiology, Hope Hospital, Salford
KEY WORDS:
Anthropometry, Computerized tomography, Low back pain, Paraspinal, Psoas muscle wasting. acute general practitioners frequently favoured a period of domiciliary conservative treatment prior to hospital referral. Waiting list times for hospital outpatient and CT appointments then added to the time elapsed between back injury and the CT scan. For these reasons 18 months was chosen as a suitable 'cutoff to separate the patient groups. Most of the recent LBP patients were suffering with sciatica and were being investigated to assess the need for decompressive spinal surgery. Most chronic patients had undergone previous lumbar surgery but continued to suffer severe back and radicular symptoms and disability, hence their further investigation. For chronic postsurgical LBP patients CT was undertaken before and following intravenous enhancement, using 100 ml omnipaque 350 (Nycomed), in order that epidural fibrosis and recurrent prolapsed intervertebral disc (PID) could be
QUADRICEPS power is an important factor in knee joint stability. In arthritis, quadriceps weakness and wasting, which are common and arise due to pain and reflex inhibition of motor efferents, impair joint stability [1, 2]. This may predispose the joint to further disruption thereby generating a vicious circle of damage [2]. Stability of the lumbar spine is also highly dependent on muscle function, a point well illustrated by the gross vertebral deformities associated with paraspinal muscle dysfunction in neuromuscular diseases [3, 4]. The question arises as to whether pain and/or inflammation arising in the lumbar spine could hamper activation of paraspinal muscles by similar mechanisms, and thus cause the weakness which has been demonstrated in previous dynanometric studies of the lumbar spine in LBP patients [5-7]. The present study radiographically quantifies paraspinal muscle dimensions in patients suffering recent and chronic mechanical LBP to investigate further the question of wasting. This study was approved by Salford Health Authority Ethical Committee.
PATIENTS AND METHODS The 87 patients studied, aged 20-55 years, were suffering LBP symptoms of sufficient severity and with appropriate characteristics to warrant computerized tomography (CT) of the lumbar spine. Relevant investigations had excluded subjects with inflammatory, metabolic, neoplastic or referred pain. Radiological comparisons were made between those patients with recent and those with chronic lumbar pain symptoms, the rationale being that paraspinal muscle wasting was more likely where symptoms were longstanding. Recent pain was defined as that lasting up to 18 months and chronic pain that lasting over 18 months. Eighteen months seems prolonged in the context of 'recent' but LBP symptoms often started insidiously so that some patients could not accurately date symptom onset. Where symptoms were obviously
FIG. 1.—Routine CT included a 'standardized' view positioned accurately along the upper end plate of L4. The other lines shown indicate the position of other transaxial views required to investigate the cause of back pain symptoms.
Submitted 20 March; revised version accepted 26 June 1991. Correspondence to R. G. Cooper, Rheumatic Diseases Centre, Hope Hospital, Salford M6 8HD. 389
Downloaded from http://rheumatology.oxfordjournals.org/ at The Australian National University on January 24, 2015
SUMMARY This study investigated whether paraspinal muscle wasting occurs in association with chronic low back pain (LBP). Crosssectional areas (CS A) of spinal and paraspinal structures were measured radiographically, at the level of L4, in 43 patients with recent and 44 with chronic LBP. Crude anthropometry demonstrated no differences between the groups with regard to L4 and paraspinal and psoas muscle CSAs, but inter-individual differences were large. Since body weight correlated significantly with L4 CSA this dimension was used as an 'internal standard' and further inter-individual comparisons were made using paraspinal:L4 and psoas:L4 (i.e. muscle to bone) CSA ratios. Muscle assessments made in this 'relative' fashion revealed significant reductions in paraspinal and psoas dimensions in patients with chronic compared to recent onset LBP. These changes could cause paraspinal and psoas muscle weakness and thereby predispose to spinal instability and progressive dysfunction.
390
BRITISH JOURNAL OF RHEUMATOLOGY VOL. XXXI NO. 6
RESULTS Computerized tomography was performed on 49 males, 26 with recent and 23 with chronic LBP, and 38 females, 17 with recent and 21 with chronic LBP. Of the total of 44 patients with chronic LBP 31 had undergone at least one previous lumbar spinal surgical procedure. A summary of the personal details and anthropometric assessments of spinal and paraspinal structures for all subjects appears in Table I. Patients with chronic LBP were significantly older than their counterparts with recent symptoms but not significantly heavier. Not unexpectedly the CSAs of L4 and paraspinal and psoas muscles were greater in males than females, for both recent and chronic patients. The within-sex differences between recent and chronic LBP patients for absolute CSA values of paraspinal and psoas were small and not significant (Table I). Inter-individual differences were large, however. The CSA of L4 did not differ between those with recent and those with chronic LBP but it did correlate significantly with body weight (Fig. 3, r = 0.688, P
RADIOGRAPHIC DEMONSTRATION OF PARASPINAL MUSCLE WASTING IN PATIENTS WITH CHRONIC LOW BACK PAIN BY R. G. COOPER, W. ST. CLAIR FORBES* AND M. I. V. JAYSON Rheumatic Diseases Centre, University of Manchester and 'Department of Neuroradiology, Hope Hospital, Salford
KEY WORDS:
Anthropometry, Computerized tomography, Low back pain, Paraspinal, Psoas muscle wasting. acute general practitioners frequently favoured a period of domiciliary conservative treatment prior to hospital referral. Waiting list times for hospital outpatient and CT appointments then added to the time elapsed between back injury and the CT scan. For these reasons 18 months was chosen as a suitable 'cutoff to separate the patient groups. Most of the recent LBP patients were suffering with sciatica and were being investigated to assess the need for decompressive spinal surgery. Most chronic patients had undergone previous lumbar surgery but continued to suffer severe back and radicular symptoms and disability, hence their further investigation. For chronic postsurgical LBP patients CT was undertaken before and following intravenous enhancement, using 100 ml omnipaque 350 (Nycomed), in order that epidural fibrosis and recurrent prolapsed intervertebral disc (PID) could be
QUADRICEPS power is an important factor in knee joint stability. In arthritis, quadriceps weakness and wasting, which are common and arise due to pain and reflex inhibition of motor efferents, impair joint stability [1, 2]. This may predispose the joint to further disruption thereby generating a vicious circle of damage [2]. Stability of the lumbar spine is also highly dependent on muscle function, a point well illustrated by the gross vertebral deformities associated with paraspinal muscle dysfunction in neuromuscular diseases [3, 4]. The question arises as to whether pain and/or inflammation arising in the lumbar spine could hamper activation of paraspinal muscles by similar mechanisms, and thus cause the weakness which has been demonstrated in previous dynanometric studies of the lumbar spine in LBP patients [5-7]. The present study radiographically quantifies paraspinal muscle dimensions in patients suffering recent and chronic mechanical LBP to investigate further the question of wasting. This study was approved by Salford Health Authority Ethical Committee.
PATIENTS AND METHODS The 87 patients studied, aged 20-55 years, were suffering LBP symptoms of sufficient severity and with appropriate characteristics to warrant computerized tomography (CT) of the lumbar spine. Relevant investigations had excluded subjects with inflammatory, metabolic, neoplastic or referred pain. Radiological comparisons were made between those patients with recent and those with chronic lumbar pain symptoms, the rationale being that paraspinal muscle wasting was more likely where symptoms were longstanding. Recent pain was defined as that lasting up to 18 months and chronic pain that lasting over 18 months. Eighteen months seems prolonged in the context of 'recent' but LBP symptoms often started insidiously so that some patients could not accurately date symptom onset. Where symptoms were obviously
FIG. 1.—Routine CT included a 'standardized' view positioned accurately along the upper end plate of L4. The other lines shown indicate the position of other transaxial views required to investigate the cause of back pain symptoms.
Submitted 20 March; revised version accepted 26 June 1991. Correspondence to R. G. Cooper, Rheumatic Diseases Centre, Hope Hospital, Salford M6 8HD. 389
Downloaded from http://rheumatology.oxfordjournals.org/ at The Australian National University on January 24, 2015
SUMMARY This study investigated whether paraspinal muscle wasting occurs in association with chronic low back pain (LBP). Crosssectional areas (CS A) of spinal and paraspinal structures were measured radiographically, at the level of L4, in 43 patients with recent and 44 with chronic LBP. Crude anthropometry demonstrated no differences between the groups with regard to L4 and paraspinal and psoas muscle CSAs, but inter-individual differences were large. Since body weight correlated significantly with L4 CSA this dimension was used as an 'internal standard' and further inter-individual comparisons were made using paraspinal:L4 and psoas:L4 (i.e. muscle to bone) CSA ratios. Muscle assessments made in this 'relative' fashion revealed significant reductions in paraspinal and psoas dimensions in patients with chronic compared to recent onset LBP. These changes could cause paraspinal and psoas muscle weakness and thereby predispose to spinal instability and progressive dysfunction.
390
BRITISH JOURNAL OF RHEUMATOLOGY VOL. XXXI NO. 6
RESULTS Computerized tomography was performed on 49 males, 26 with recent and 23 with chronic LBP, and 38 females, 17 with recent and 21 with chronic LBP. Of the total of 44 patients with chronic LBP 31 had undergone at least one previous lumbar spinal surgical procedure. A summary of the personal details and anthropometric assessments of spinal and paraspinal structures for all subjects appears in Table I. Patients with chronic LBP were significantly older than their counterparts with recent symptoms but not significantly heavier. Not unexpectedly the CSAs of L4 and paraspinal and psoas muscles were greater in males than females, for both recent and chronic patients. The within-sex differences between recent and chronic LBP patients for absolute CSA values of paraspinal and psoas were small and not significant (Table I). Inter-individual differences were large, however. The CSA of L4 did not differ between those with recent and those with chronic LBP but it did correlate significantly with body weight (Fig. 3, r = 0.688, P
