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Neurocrit Care. 2017 Oct;27(2):199-207. doi: 10.1007/s12028-017-0399-2.

Revisiting Grade 3 Diffuse Axonal Injury: Not All Brainstem Microbleeds are Prognostically Equal.

Author information

1
Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. Sizzy@bwh.harvard.edu.
2
Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA. Sizzy@bwh.harvard.edu.
3
Department of Physical Medicine and Rehabilitation, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
4
Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
5
Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
6
Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA.
7
Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
8
Program in Trauma, Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, USA.
9
Department of Neurology, Yale-New Haven Hospital, Yale School of Medicine, New Haven, CT, USA.
10
Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.
11
Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.

Abstract

BACKGROUND:

Recovery of functional independence is possible in patients with brainstem traumatic axonal injury (TAI), also referred to as "grade 3 diffuse axonal injury," but acute prognostic biomarkers are lacking. We hypothesized that the extent of dorsal brainstem TAI measured by burden of traumatic microbleeds (TMBs) correlates with 1-year functional outcome more strongly than does ventral brainstem, corpus callosal, or global brain TMB burden. Further, we hypothesized that TMBs within brainstem nuclei of the ascending arousal network (AAN) correlate with 1-year outcome.

METHODS:

Using a prospective outcome database of patients treated for moderate-to-severe traumatic brain injury at an inpatient rehabilitation hospital, we retrospectively identified 39 patients who underwent acute gradient-recalled echo (GRE) magnetic resonance imaging (MRI). TMBs were counted on the acute GRE scans globally and in the dorsal brainstem, ventral brainstem, and corpus callosum. TMBs were also mapped onto an atlas of AAN nuclei. The primary outcome was the disability rating scale (DRS) score at 1 year post-injury. Associations between regional TMBs, AAN TMB volume, and 1-year DRS score were assessed by calculating Spearman rank correlation coefficients.

RESULTS:

Mean ± SD number of TMBs was: dorsal brainstem = 0.7 ± 1.4, ventral brainstem = 0.2 ± 0.6, corpus callosum = 1.8 ± 2.8, and global = 14.4 ± 12.5. The mean ± SD TMB volume within AAN nuclei was 6.1 ± 18.7 mm3. Increased dorsal brainstem TMBs and larger AAN TMB volume correlated with worse 1-year outcomes (R = 0.37, p = 0.02, and R = 0.36, p = 0.02, respectively). Global, callosal, and ventral brainstem TMBs did not correlate with outcomes.

CONCLUSIONS:

These findings suggest that dorsal brainstem TAI, especially involving AAN nuclei, may have greater prognostic utility than the total number of lesions in the brain or brainstem.

KEYWORDS:

Brainstem; Diffuse axonal injury; Gradient-recalled echo MRI; Traumatic axonal injury; Traumatic brain injury; Traumatic microbleed

PMID:
28477152
PMCID:
PMC5877823
DOI:
10.1007/s12028-017-0399-2
[Indexed for MEDLINE]
Free PMC Article

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