Abstract
Background:
Brain Computed Tomography (CT) is a fundamental diagnostic test to evaluate
traumatic brain injury (TBI) patients. The optic nerve sheath (ONS) has been
increasingly studied as an objective and practical parameter for estimating the
existence of intracranial hypertension and for prognosis assessment. The aim of
this study was to evaluate different measures in the optic nerve sheath as
prognostic tools.
Methods: A
retrospective cohort of patients with moderate and severe TBI admitted to the
Intensive Care Unit (ICU) between April and September 2018. The following
measurements of the ONS were performed on admission CT: diameter at 3mm
(ONSD-3) and 10mm (ONSD-10) from the eyeball in the axial plane; ratio between
the ONS-3 or the ONS-10 and the transverse diameter of the eyeball, resulting
in NER-3 and NER-10; and cross-sectional area at 3mm (ONSA-3) and 10mm from the
eyeball (ONSA-10). The association between measures and hospital mortality was
investigated. A combined secondary outcome was defined as craniotomy within 5
days and/or death.
Results: 81
patients were included. Mean age was 36.3 +/- 15.8 years. 93% were men. 41%
underwent craniotomy. Hospital mortality was 41%, while 72% had a combined
outcome. None of the tomographic variables were significantly associated with
in-hospital mortality. Craniotomy was a protective factor (p = 0.01). When
considering the combined outcome, only ONSD-10 and NER-10 presented a
significant association (p = 0.03 and p = 0.005, respectively). In the subgroup
of non-operated patients, ONSD-10 and NER-10 demonstrated independent
prognostic value for hospital mortality, with cut-off values of ONSD-10 >
4.3mm (AOR = 14.24, p = 0.03) and NER-10 > 0.19 (AOR = 24.87, p = 0.03).
Conclusion: The ONSD-10 and
NER-10 measurements showed a better association with prognosis compared to
measurements taken at 3mm, as well as other tomographic parameters for patients
with moderate and severe TBI.