Nerve Root Sedimentation Sign in Lumbar Stenosis
27/04/10 21:08 Filed in: Clinical Pearls
One of the great challenges facing the front-line clinician is to decide whether a radiological finding is actually relevant.
I’m sure that you are all too aware that many ‘abnormalities’ seen on imaging studies are present in an asymptomatic population (for example, 52% of asymptomatic individuals have at least one disc bulge evident on MRI(1)).
So what about lumbar spinal stenosis? When a patient complains of leg pain while walking (claudication), how can we tell whether the stenosis visualised on their MRI scan is relevant and demonstrates the cause of their symptoms? Or should we keep looking for another source of pain? Perhaps their complaint is vascular in origin?
A new study published in the journal SPINE might possibly help us in our quest for clinical clarity.
In the paper by Barz et al(2) the authors describe a promising sign on MRI scans of supine patients (this won’t work in the new upright MRI machines).
In a normal supine patient the nerve roots of the cauda equina will ‘settle’ to the posterior aspect of the spinal canal under gravity. However, when a patient suffers from symptomatic lumbar spinal stenosis you can often observe a failure of the roots to form this ‘sediment’. In other words, they remain fairly evenly distributed throughout the spinal canal, as they are effectively being held in place by the constriction of the anatomy producing the stenosis (usually a combination of disc bulging, ligamentum flavum hypertrophy and facet joint osteoarthrosis).
The diagram below (taken from the original article ©2010, Lippincott Williams & Wilkins) demonstrates this effect.
But how reliable is this nerve root sedimentation sign?
Well, according to Barz et al “A positive sedimentation sign exclusively and reliably occurs in patients with symptomatic lumbar spinal stenosis, suggesting its usefulness in clinical practice.” In fact, in their study this sign was found in 94% of symptomatic spinal stenosis patients, yet found in none of those individuals suffering only from non-specific low back pain.
So, next time you are faced with a patient suffering from apparent claudication it would be worth looking for the presence of nerve root sedimentation.
Dr Matthew D. Long - BSc. M.Chiro
References:
1. Jensen MC, Brant-Zawadzki MN, Obuchowski N, Modic MT, Malkasian D, Ross JS. Magnetic Resonance Imaging of the Lumbar Spine in People without Back Pain. NEJM. 1994. 331: 69-73
2. Barz T, Melloh M, Staub LP, Lord SJ, Lange J, Roder CP, Theis JC, Merk HR. Nerve Root Sedimentation Sign - Evaluation of a New Radiological Sign in Lumbar Spinal Stenosis. SPINE 2010. 35 (8): 892-897
I’m sure that you are all too aware that many ‘abnormalities’ seen on imaging studies are present in an asymptomatic population (for example, 52% of asymptomatic individuals have at least one disc bulge evident on MRI(1)).
So what about lumbar spinal stenosis? When a patient complains of leg pain while walking (claudication), how can we tell whether the stenosis visualised on their MRI scan is relevant and demonstrates the cause of their symptoms? Or should we keep looking for another source of pain? Perhaps their complaint is vascular in origin?
A new study published in the journal SPINE might possibly help us in our quest for clinical clarity.
In the paper by Barz et al(2) the authors describe a promising sign on MRI scans of supine patients (this won’t work in the new upright MRI machines).
In a normal supine patient the nerve roots of the cauda equina will ‘settle’ to the posterior aspect of the spinal canal under gravity. However, when a patient suffers from symptomatic lumbar spinal stenosis you can often observe a failure of the roots to form this ‘sediment’. In other words, they remain fairly evenly distributed throughout the spinal canal, as they are effectively being held in place by the constriction of the anatomy producing the stenosis (usually a combination of disc bulging, ligamentum flavum hypertrophy and facet joint osteoarthrosis).
The diagram below (taken from the original article ©2010, Lippincott Williams & Wilkins) demonstrates this effect.
But how reliable is this nerve root sedimentation sign?
Well, according to Barz et al “A positive sedimentation sign exclusively and reliably occurs in patients with symptomatic lumbar spinal stenosis, suggesting its usefulness in clinical practice.” In fact, in their study this sign was found in 94% of symptomatic spinal stenosis patients, yet found in none of those individuals suffering only from non-specific low back pain.
So, next time you are faced with a patient suffering from apparent claudication it would be worth looking for the presence of nerve root sedimentation.
Dr Matthew D. Long - BSc. M.Chiro
References:
1. Jensen MC, Brant-Zawadzki MN, Obuchowski N, Modic MT, Malkasian D, Ross JS. Magnetic Resonance Imaging of the Lumbar Spine in People without Back Pain. NEJM. 1994. 331: 69-73
2. Barz T, Melloh M, Staub LP, Lord SJ, Lange J, Roder CP, Theis JC, Merk HR. Nerve Root Sedimentation Sign - Evaluation of a New Radiological Sign in Lumbar Spinal Stenosis. SPINE 2010. 35 (8): 892-897
blog comments powered by Disqus
