Discrepancies between cerebral perfusion and metabolism after subarachnoid haemorrhage: a magnetic resonance approach
- Jeremy Rowea,b,
- Andrew M Blamirea,
- Zayne Domingoa,
- Virginia Moodyc,
- Andrew Molyneuxc,
- James Byrnec,
- Thomas Cadoux-Hudsona,b,
- George Raddaa
- aMRC Magnetic Resonance Spectroscopy Unit, John Radcliffe Hospital, Oxford, UK, bDepartment of Neurosurgery, cDepartment of Neuroradiology, Radcliffe Infirmary, Oxford, UK
- Dr Jeremy Rowe, Department of Neurosurgery, Radcliffe Infirmary, Woodstock Road, Oxford OX2 6HE, UK. Telephone 0044 1865 311188; fax 0044 1865 224898.
- Received 11 December 1996
- Revised 11 June 1997
- Accepted 7 July 1997
Abstract
INTRODUCTION There is a variable relation between angiographic vasospasm and delayed ischaemic neurological deficit (DIND). Magnetic resonance (MR) techniques have the potential to investigate the haemodynamic, metabolic, and structural changes occurring with these complications. These techniques have been applied to study DIND in patients recovering from subarachnoid haemorrhage.
METHODS Fifteen studies were performed on 11 patients, 10 with DIND. Vasospasm was diagnosed angiographically or with transcranial Doppler. The MR protocol consisted of T2 weighted imaging, contrast enhanced dynamic perfusion scanning, TI weighted imaging, and two dimensional localised proton spectroscopy. Relative cerebral blood volume maps were generated from perfusion scans. Metabolite ratios were calculated from proton spectra.
RESULTS All patients had cortical oedema on T2 weighted images, significantly more pronounced in patients of poor clinical grade (p<0.01). Spectra were normal in good grade patients. Lactate was increased and N-acetyl aspartate decreased in the poor grades, significantly worse in grade 4 compared with grade 3 patients (p<0.05). Spectral changes also correlated with the severity of oedema (p<0.05). Relative blood volumes were significantly higher in oedematous regions of poor compared with good grade patients (p<0.05). Lactate was seen in regions of the brain with increased relative blood volume.
CONCLUSIONS Despite the paramagnetic effects of haemorrhage, or of the coils and clips used to treat aneurysms, this study demonstrates that patients recovering from subarachnoid haemorrhage can undergo complex MR studies. Oedema, lactate, and increased relative blood volume correlate well with each other and with DIND and poor clinical grade.
