Two cases of traumatic head injury mimicking acute encephalopathy with biphasic seizures and late reduced diffusion

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.

Acute subdural hematoma in an infant with a biphasic clinical course and late reduced diffusion

Background

Bright tree appearance (BTA) is a characteristic finding on diffusion-weighted magnetic resonance (MR) imaging with transient high intensity in the white matter. BTA is characteristic of infants with acute encephalopathy with biphasic seizures, but it has also been reported in head trauma cases. In this report, we describe an infant case of traumatic brain injury that demonstrated a biphasic clinical course and late reduced diffusion (TBIRD).

Case Description

A 5-month-old boy suffered from head trauma and developed coma and seizures. Computed tomography scans revealed acute subdural hematoma on the right side. He underwent an emergency operation to remove the hematoma but subsequently had seizure clusters for three days. Diffusion-weighted MR imaging revealed BTA in the right cerebral hemisphere. He was treated with antiepileptic agents and fully recovered to pre-injury condition, and MR imaging no further revealed any BTA 20 days after head trauma. He developed no complications at the 10-month postoperative follow-up.

Conclusion

We reported a case of TBIRD following head trauma in the infant. The pathogenesis remains unclear, but we consider the possibility of biphasic seizures in infant head trauma cases, and we should appropriately administer the anticonvulsants and carefully check for MR imaging.

Infantile Hypoxic Encephalopathy Mimicking Acute Encephalopathy with Biphasic Seizures and Late Reduced Diffusion (AESD) Identified as an Episode of Brief Resolved Unexplained Event (BRUE)

Acute encephalopathy with biphasic seizures and reduced diffusion (AESD) is characterized by biphasic seizures following febrile viral infections and delayed reduced diffusion of the cerebral white matter on magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) (bright tree appearance, BTA). However, hypoxic encephalopathy with biphasic seizures and AESD-mimicking imaging findings has not been reported. We report a case of hypoxic encephalopathy due to suffocation with concomitant biphasic seizures and BTA, mimicking AESD. On day 1, a healthy 5-month-old girl was found face down with decreased breathing and a deteriorating consciousness level, suggesting a brief resolved unexplained event (BRUE). Electroencephalography (EEG) revealed periodic epileptic discharges, suggesting possible nonconvulsive status epilepticus. Despite improvements in consciousness level and EEG abnormalities on day 2, her consciousness level deteriorated again with generalized tonic-clonic seizures on day 3, and a head MRI-DWI revealed restricted diffusion predominantly in the subcortical areas, suggesting BTA. Treatment for acute encephalopathy resolved the clinical seizures and EEG abnormalities. Persistence of abnormal EEG, reflecting abnormal excitation and accumulation of neurotoxic substances caused by hypoxia, may have contributed to the development of AESD-like findings. As hypoxic encephalopathy causes AESD-like biphasic seizures, monitoring consciousness level, seizure occurrence, and EEG abnormalities even after acute symptoms have temporarily improved following hypoxia is essential.

An infantile traumatic brain injury with a bright tree appearance detected before the late seizure

INDRODUCTION

Infantile traumatic brain injury (TBI) rarely follows a biphasic clinical course and exhibits a bright tree appearance (BTA) on magnetic resonance imaging (MRI). This is termed infantile traumatic brain injury with a biphasic clinical course and late reduced diffusion (TBIRD). TBIRD has clinical features similar to those of acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). It remains to be clarified which patients with infantile TBI will develop TBIRD and the prevention and treatment of TBIRD.

CASE AND REVIEW

We report a case of TBIRD that exhibited BTA 1 day before the late seizure and review 12 cases of TBIRD. All patients developed a subdural hematoma (SDH), were younger than 2 years, and presented with a biphasic phase within 3-6 days. The median interval between BTA and TBI was 5 days. Of the 5 cases examined with MRI before the biphasic phase, only our case was detected with BTA 4 days after TBI.

CONCLUSION

Predicting the biphasic clinical course may be possible by examining MRI after TBI in patients under 2 years of age who develop SDH with unconsciousness, seizure, or hemiplegia, and these patients should be strictly followed up for 1 week.

Detailed characteristics of acute encephalopathy with biphasic seizures and late reduced diffusion: 18-year data of a single-center consecutive cohort

OBJECTIVE

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a syndrome characterized by biphasic seizures with impaired consciousness. AESD is rare outside Asia, and consecutive cohort studies are therefore scarce. Herein, we aimed to describe the detailed characteristics of AESD, including clinical course, electroencephalogram data, laboratory data, imaging findings, treatment, and outcomes.

METHODS

We reviewed the clinical database and medical charts of 43 consecutive pediatric patients (<18 years old) who developed AESD between October 1, 2002, and September 30, 2019.

RESULTS

We found that AESD occurred even though patients did not develop prolonged seizures. A comparison between the two groups (first seizure duration <30 min and first seizure duration ≥30 min) revealed three main findings: first, patients with AESD who had shorter seizures had better prognosis than those with prolonged seizures; second, patients with AESD who had shorter seizures tended to have earlier occurrence of a second seizure; and third, high signal intensity on diffusion-weighted magnetic resonance imaging was observed mainly in frontal areas, not diffusely, in patients with shorter seizures, and in a broader area in patients with prolonged seizures.

CONCLUSIONS

Our description of the detailed clinical picture of AESD may add new insight into its pathophysiology.

Vascular pathomechanism in acute encephalopathy with biphasic seizures and late reduced diffusion

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a childhood-onset encephalopathy, but the precise pathophysiology remains unclear. We encountered a child with Moyamoya syndrome and AESD. He exhibited left-predominant stenosis of the middle cerebral artery (MCA), and later developed broad lesions in the left hemisphere, raising the possibility that insufficient blood supply relates to formation of the lesions. To test the hypothesis, we investigated the relationship between MCA volume and lesion extent in seven AESD children without preexisting diseases. The MCA volume and lesion extent were quantified with time of flight images for construction of magnetic resonance angiography and apparent diffusion coefficient maps, respectively. Lateralization indices ([right - left]/[right + left]) of the MCA volume and lesion extent were calculated. We found that the lateralization indices were negatively correlated (r = -0.786, p = .036), that is, when the MCA volume was smaller in one side than the other side, the lesions were likely to develop more extensively in the ipsilateral side than the contralateral side. This indicates the association of insufficient blood supply with the lesions. The present study provides the first observation to suggest the involvement of vascular mechanism in AESD and has potential implications for novel therapeutic approach.

Acute encephalopathy with biphasic seizures and late reduced diffusion associated with staphylococcal toxic shock syndrome caused by burns

We report a case of acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) associated with toxic shock syndrome caused by burns. A one-year-old girl was admitted to our hospital for treatment of severe burns. On day 3, she exhibited a fever, generalized rash and multiple organ failure. She was diagnosed with toxic shock syndrome after burns. She had seizures with fever twice on the same day, followed by secondary seizures on day 8 and transient deterioration of the gross motor functions involved in sitting alone and rolling over. On day 9, MRI diffusion-weighted images showed bright tree appearance (BTA). We conclude that she developed AESD.

Traumatic head injury mimicking acute encephalopathy with biphasic seizures and late reduced diffusion

Many studies have reported acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) associated with viral infection at onset, but few studies have reported AESD without infection. We report the case of a 9-month-old boy who had a clinical course mimicking AESD after a traffic accident. The traffic accident caused a mild subdural hematoma without neurological abnormalities on admission. The boy became unconscious on the second day, and he was diagnosed with non-convulsive status epilepticus on the third day. Diffusion-weighted imaging showed reduced water diffusion in the subcortical white matter. On laboratory analysis interleukin (IL)-6 was elevated in the cerebrospinal fluid (CSF), but not in the serum. He had severe neurological sequelae with mental retardation, spastic tetraplegia, and epilepsy. We suggest that brain damage mimicking AESD was caused by the traffic accident and the prolonged seizure during infancy.