Date of Award

6-30-2011

Document Type

Dissertation

Degree Name

Master of Medicine (MMed)

First Supervisor/Advisor

Sandeep Velicheti

Department

Imaging and Diagnostic Radiology (East Africa)

Abstract

Objective: The objective of this study was to stratify white matter hyperintensities on the basis of neuronal integrity in young and middle age adults by comparing the level of N-acetyl aspartate and creatine ratios in white matter hyperintensity lesions and normal appearing white matter using hydrogen magnetic resonance (H-MR) spectroscopy at 1.5 Tesla(T)

Methods: Fifty consecutive patients who fulfilled the inclusion criteria aged 18-50yrs who were referred for magnetic resonance imaging(MRI) of the brain at the Radiology department of Aga Khan University Hospital over a six month period between January and June 2011 were included in the study. These patients had undergone routine MRI brain using the department protocol and were found to have white matter hyperintensities ≥5mm and no other intra-axial abnormalities.

The patients underwent MR spectroscopy of the white matter hyperintensity lesions and a corresponding region of normal appearing white matter at 1.5 Tesla.

Ratios of N-acetyl aspertate/creatine were compared for the white matter hyperintensity lesions and normal appearing white matter. The NAA/creatine ratios of the white matter hyperintensities and normal appearing white matter were analyzed and inferences made regarding neuronal integrity, clinical presentation and location of the white matter lesions. Results:Fifty patients, 25 male and 25 female were included in the final analysis. Thirty nine (78%) patients showed lower levels of NAA/creatine ratios in the white matter hyperintensities compared to normal appearing white matter. Eleven (22%) patients showed higher levels of NAA/creatine ratios in the white matter hyperintensities compared to normal appearing white matter. Paired T test showed a statistically significant difference between the NAA/creatine ratios in the white matter hyperintensity lesions compared to normal white matter(p value of

Forty seven (94%) sampled lesions were in the subcortical and deep white matter compared to 3(6%) lesions in the periventricular location. There was no statistically significance difference in the ratios of NAA/creatine between the periventricular and deep white matter lesions.

Forty seven (94%) of the study patients presented with headache . Twelve (24%) presented with dizziness. No correlation was found between the levels of NAA/creatine ratios and clinical presentation.

Conclusion: This study demonstrates that white matter hyperintensities in young and middle age adults are associated with actual neuronal destruction. These patients should be investigated to define the aetiology and if possible interventions to reverse or prevent further neuronal damage.

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