MRI evidence of disc herniation is not predictive of clinical outcome in sciatica

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Image: PD

1.  The presence of disc herniation or nerve root impingement on MRI did not distinguish patients with a favorable outcome from those with an unfavorable outcome.  

2.  Approximately 1/3 of patients treated for sciatica will demonstrate disc herniation on MRI, regardless of clinical outcome.  

In patients treated either surgically or conservatively for sciatica, MRI findings of disc herniation or nerve root compression are not predictive of clinical outcome.  MRI showed disc herniation in approximately 1/3 of patients regardless of whether their symptoms were resolved.  Traditionally, MRI has been the imaging modality of choice for the assessment of suspected disc herniation in the context of sciatica.  A lack of correlation between MRI findings and clinical outcomes suggests that this modality does not adequately address the complex and multifactorial nature of sciatica.  The findings of this study serve to question the role of MRI in clinical decision making for the treatment of sciatica.

The criteria used to determine a “favorable” vs “unfavorable” outcome was limited to a single patient-reported quality of life measure (7-point Likert Scale).  The addition of a physician perspective on clinical improvement could markedly enhance the impact of this study.

Click to read the study in NEJM  

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Image: PD

1.  The presence of disc herniation or nerve root impingement on MRI did not distinguish patients with a favorable outcome from those with an unfavorable outcome. 

2.  Approximately 1/3 of patients treated for sciatica will demonstrate disc herniation on MRI, regardless of clinical outcome. 

This [prospective, randomized] study  included 267 patients with 6 to 12 weeks of sciatica with disc herniation as seen on MRI.  Subjects were randomized to undergo surgery as a primary intervention or to receive prolonged conservative care.  If conservative measures did not improve symptoms by six months, surgery was offered.  All patients underwent MRI at baseline and at 1 year including sagittal and axial T1 and T2-weighted images.  Three specialists evaluated imaging for level and severity of herniation, and presence of nerve root compression.  Clinical outcomes were assessed via the 7-point Likert self-rating scale for global perceived recovery.  A favorable clinical outcome was defined as complete or near-complete disappearance of symptoms by 1 year as assessed by this tool.

At one year, MRI showed disc herniation in 35% of patients with a favorable outcome and 33% of patients with an unfavorable outcome.  Radiographic evidence of nerve root compression was found in 24% of patients with a favorable outcome and 26% of those with an unfavorable outcome.  Neither the presence nor the severity of herniation or nerve root impingement on MRI distinguished between patients with a favorable or unfavorable outcome. 

In sum:  In patients treated either surgically or conservatively for sciatica, MRI findings of disc herniation or nerve root compression are not predictive of clinical outcome.  MRI showed disc herniation in approximately 1/3 of patients regardless of whether their symptoms were resolved.  Traditionally, MRI has been the imaging modality of choice for the assessment of suspected disc herniation in the context of sciatica.  A lack of correlation between MRI findings and clinical outcomes suggests that this modality does not adequately address the complex and multifactorial nature of sciatica.  The findings of this study serve to question the role of MRI in clinical decision making for the treatment of sciatica.

The criteria used to determine a “favorable” vs “unfavorable” outcome was limited to a single patient-reported quality of life measure (7-point Likert Scale).  The addition of a physician perspective on clinical improvement could markedly enhance the impact of this study.

Click to read the study in NEJM 

By Chaz Carrier and Allen Ho

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