PAPER

Acute metabolic brain changes following traumatic brain injury and their relevance to clinical severity and outcome

Silvia Marino¹, Ettore Zei³, Marco Battaglini¹, Cesare Vittori³, Antonella Buscalferri³, Placido Bramanti², Antonio Federico¹ and Nicola De Stefano¹

¹ Department of Neurological and Behavioural Sciences, University of Siena, Siena, Italy
² IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy
³ Department of Anesthesia and Intensive Care, University of Siena, Siena, Italy

Correspondence to:
Correspondence to:
Dr N De Stefano
Department of Neurological and Behavioural Sciences, Neurology & Neurometabolic Unit, University of Siena, Viale Bracci 2, 53100 Siena, Italy; destefano{at}unisi.it

Background: Conventional MRI can provide critical information for care of patients with traumatic brain injury (TBI), but MRI abnormalities rarely correlate to clinical severity and outcome. Previous magnetic resonance spectroscopy studies have reported clinically relevant brain metabolic changes in patients with TBI. However, these changes were often assessed a few to several days after the trauma, with a consequent variation of the metabolic pattern due to temporal changes.

Methods: Proton magnetic resonance spectroscopic imaging (¹H-MRSI) examinations were performed in 10 patients with TBI 48–72 h after the trauma, to obtain early measurements of central brain levels of N-acetylaspartate (NAA), choline (Cho), creatine (Cr) and lactate (La). Metabolite values were expressed as ratios to (1) a metabolic pattern, given by the sum of the resonance intensities of all metabolites detected in the same voxel and (2) intravoxel Cr.

Results: NAA ratios were found to be significantly lower in patients with TBI than in normal controls. In contrast, Cho ratios were significantly higher in patients with TBI than in normal controls. Increased La levels were found in 5 of 10 patients with TBI. Both NAA and La values correlated closely with those of the Glasgow Coma Scale at presentation (r = 0.73 and –0.62, respectively; p<0.01 for both) and the Glasgow Outcome Scale at 3 months (r = –0.79 and 0.79, respectively; p<0.01 for both).

Conclusion: Spectroscopic measures of neuro-axonal damage occurring soon after a brain trauma are clinically relevant. Significant increases in cerebral La level also may be detected when ¹H-MRSI is performed early after the trauma and, at this stage, can represent a reliable index of injury severity and disease outcome in patients with TBI.

Abbreviations: Cho, choline; Cr, creatine; GCS, Glasgow Coma Scale; GOS, Glasgow Outcome Scale; ¹H-MRS, voxel proton magnetic resonance spectroscopy; ¹H-MRSI, proton magnetic resonance spectroscopic imaging; La, lactate; MR, magnetic resonance; NAA, N-acetylaspartate; NC, normal control; TBI, traumatic brain injury; TE, echo time; TR, repetition time; VOI, volume of interest

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