Factors influencing the development of infantile traumatic brain injury with a biphasic clinical course and late reduced diffusion.

BACKGROUND: Infantile traumatic brain injury (TBI) with a biphasic clinical course and late reduced diffusion (TBIRD) has been reported as a type of TBI. However, it remains uncertain which pediatric patients with TBI develop TBIRD. METHODS: Patients with TBI who were admitted to our hospital and underwent magnetic resonance imaging (MRI) between December 2006 and October 2022 were included in this study. A diagnosis of TBIRD was made in patients with or suspected TBI, with initial symptoms being convulsions or disturbance of consciousness and late-onset subcortical reduced diffusion, the so-called bright tree appearance. Clinical features, neuroimaging (computed tomography (CT) and MRI) findings, laboratory data, and Tada score were retrospectively compared between TBIRD and non-TBIRD patients. Neurological prognosis was assessed using the Pediatric Cerebral Performance Category scale. RESULTS: Of 21 patients who met the inclusion criteria, a diagnosis of TBIRD was made in 7 patients (median age: 8 months). The factors contributing to TBIRD development were seizures lasting over 30 min as the initial symptom (5/7 in TBIRD vs. 0/14 in non-TBIRD), tracheal intubation during initial treatment (5/7 vs. 0/14), and brain parenchymal lesions on CT (3/7 vs. 0/14), suggesting that severe TBI may progress to TBIRD. The Tada score was more positive in patients with TBIRD (6/7) than in those without (0/14). CONCLUSIONS: It is important to monitor infant patients with severe TBI for the development of TBIRD. The Tada score can be a useful tool for TBIRD prediction.

Pathomechanism of infantile traumatic brain injury with a biphasic clinical course and late reduced diffusion evaluated by MR spectroscopy.

BACKGROUND: Infantile traumatic brain injury (TBI) with a biphasic clinical course and late reduced diffusion (TBIRD) has recently been reported as a distinct type of TBI in infancy. However, the pathological and prognostic factors of TBIRD remain unknown. We aimed to compare patients with and without TBIRD and evaluate the pathomechanism of TBIRD using magnetic resonance spectroscopy (MRS). METHODS: Ten Japanese patients with TBI were admitted to our hospital and underwent MRS between September 2015 and September 2022 (age range, 3-15 months; median age, 8.5 months). TBIRD was diagnosed in six patients. MRS data were compared among patients with TBIRD, patients without TBIRD, and controls. Neurological prognosis was classified into grades 1 (normal) to 3 (severe). RESULTS: In patients with TBIRD, MRS revealed an increase in the glutamine (Gln) level on days 3-29, which subsequently became close to normal. The degree of Gln elevation in the non-TBIRD group was smaller (117-158 % of controls) than that in the TBIRD group (210-337 %) within 14 days. MRS in the TBIRD group showed decreased N-acetyl aspartate (NAA) concentrations. The degree of NAA decrease was more prominent in grade 3 than in grades 1 and 2. NAA levels in the non-TBIRD group were almost normal. CONCLUSIONS: Patients with TBI and markedly elevated Gln levels on MRS may develop TBIRD. Neuro-excitotoxicity is a possible pathological mechanism of TBIRD. Decreased NAA levels may be useful for predicting the prognosis of patients with TBIRD.