Transient reduced diffusion in the cortex in a child with prolonged febrile seizures

Brain Perfusion, Hippocampal Volumetric, and Diffusion-weighted Imaging Findings in Children with Prolonged Febrile Seizures and Focal Febrile Seizures

Background:

The current study was conducted to describe the findings of brain perfusion, hippocampal volumetric, and diffusion-weighted imaging (DWI) in children aged six months to seven years with febrile status epilepticus (FSE) and focal febrile seizures (FFS) when compared with age and gender-matched controls.

Materials and Methods:

This cross-sectional study was conducted among children aged six months to seven years presenting with FSE or FFS within 72 h of the seizure. Cases were subjected to magnetic resonance imaging (MRI) brain and sleep-deprived electroencephalography. Age and gender-matched children who were subjected to MRI brain for nonepileptic indications served as their control. Hippocampal volumes, T2 values, cerebral blood flow, and diffusion characteristics were compared between the cases and controls and also between those with FSE and FFS.

Results:

A total of 31 cases (FFS = 20, FSE = 11) and 30 controls were enrolled. There was no significant difference between right and left hippocampal volumes and T2 relaxometry values between cases and controls and also between children with FSE and FFS. Similarly, the cerebral blood flow was also comparable in cases and controls. There was a single case of FSE with hippocampal malrotation; one child showed diffusion restriction in the hippocampus after prolonged (>60 min) FSE.

Conclusion:

Children with FSE and FFS had comparable hippocampal volume and brain perfusion to healthy children. However, one child with FSE had hippocampal malrotation and another had diffusion restriction. The study findings need to be interpreted in the context of small sample size, and lack of follow-up neuroimaging.

Transient cortical diffusion restriction in children immediately after prolonged febrile seizures

AIM

Little is known about acute febrile status epilepticus-induced injury of extrahippocampal structures. To clarify the presence and clinical significance of acute extrahippocampal injuries, we performed diffusion-weighted imaging (DWI) in children immediately after prolonged febrile seizure (PFS).

METHOD

We performed a retrospective cohort study in children younger than 6 years old who visited one of two hospitals due to PFSs between January 2013 and October 2018. PFS was defined as a febrile seizure that persisted for 15 min or longer. We collected brain DWI data within 6 h of the end of PFS. When the initial DWI detected an abnormality, a follow-up DWI was performed a few days later.

RESULTS

The study population consisted of 101 patients with PFSs. DWI was performed within 6 h in 51 patients, while the remaining 50 patients did not undergo imaging because of good recovery of consciousness. Restricted cortical diffusion was evident in 9 (18%) patients on initial DWI. All of them underwent DWI within 100 min after PFS. Restricted cortical diffusion was associated with male sex, asymmetrical PFS symptoms, and a shorter duration between the end of the seizure and DWI, but was not associated with seizure duration. All cortical abnormalities had resolved on follow-up DWI of these patients within 72 h after the initial imaging, but ipsilateral hippocampal hyperintensity appeared in one patient. All 9 patients with restricted cortical diffusion were finally diagnosed with PFS and discharged without sequelae.

CONCLUSIONS

Some children with PFSs exhibit transient restricted diffusion in the regional cortex on DWI performed immediately after the end of PFS. These transient diffusion changes were not associated with unfavorable epileptic sequelae or neuroimaging in the short-term.

Cerebellar Hypoperfusion in Migraine Attack: Incidence and Significance

BACKGROUND AND PURPOSE

Patients diagnosed with migraine with aura have an increased lifetime risk of ischemic stroke. It is not yet clear whether prolonged cortical hypoperfusion during an aura increases the immediate risk of cerebellar infarction because it may induce crossed cerebellar diaschisis and subsequent tissue damage. To address this question, we retrospectively analyzed potential relationships between cortical oligemia and cerebellar hypoperfusion in patients with migraine with aura and their potential relation to small infarct-like cerebellar lesions.

MATERIALS AND METHODS

One hundred six migraineurs who underwent MR imaging, including DSC perfusion, were included in the study. In patients with apparent perfusion asymmetry, we used ROI analysis encompassing 18 infra- and supratentorial ROIs to account for differences in regional cerebral blood flow and volume. The presence of cerebellar hypoperfusion was calculated using an asymmetry index, with values of >10% being considered significant.

RESULTS

We observed perfusion asymmetries in 23/106 patients, 22 in patients with migraine with aura (20.8%). Cerebellar hypoperfusion was observed in 12/23 patients (52.2%), and crossed cerebellar diaschisis, in 9/23 patients (39.1%) with abnormal perfusion. In none of the 106 patients were DWI restrictions observed during migraine with aura.

CONCLUSIONS

Cerebellar hypoperfusion and crossed cerebellar diaschisis are common in patients with migraine with aura and cortical perfusion abnormalities. Crossed cerebellar diaschisis in migraine with aura may be considered a benign phenomenon because we observed no association with DWI restriction or manifest cerebellar infarctions, even in patients with prolonged symptom-related perfusion abnormalities persisting for up to 24 hours.

Prognostic and Mechanistic Factors Characterizing Seizure-Associated Crossed Cerebellar Diaschisis

BACKGROUND

Crossed cerebellar diaschisis is a rare finding of hemispheric cerebellar depression following contralateral cerebral injury, hypothesized to result from excessive neuronal excitatory synaptic activity along cortico-pontine-cerebellar pathways. The phenomenon is typically observed following ischemic stroke, but has also been characterized during seizure activity--in particular, status epilepticus (SE). Neurological outcome has varied widely in published reports, with some patients achieving full neurologic recovery, while others experience persistent disability.

METHODS

Case report and literature review.

RESULTS

We present a 54-year-old man found unresponsive with a right hemispheric syndrome several days after discharge following amygdalohippocampectomy for refractory right temporal lobe epilepsy. Prolonged electroencephalogram demonstrated one subclinical right frontal seizure, along with right frontal periodic lateralized epileptiform discharges, presumed to be associated with SE preceding his admission. Initial MRI demonstrated restricted diffusion on diffusion weighted imaging in the right cerebral hemisphere, ipsilateral thalamus, and contralateral cerebellum. A head CT one week later showed diffuse sulcal effacement with loss of gray-white differentiation in the right frontal and insular regions with low attenuation changes of right thalamus. An MRI showed worsened diffusion restriction, despite a corresponding increase in perfusion. The patient remained paretic at discharge and follow-up. Follow-up MRI at 2 months demonstrated pronounced right cerebral and left cerebellar atrophy, loss of gray matter in much of the right cerebrum, and scattered areas of T2 hyperintensity, consistent with permanent right fronto-temporal neuronal loss.

CONCLUSIONS

Collectively, these observations indicate that imaging findings of persistent cerebral restricted diffusion and cytotoxic edema in the subacute post-ictal period may predict irreversible neuronal injury and poor long-term outcome-even when accompanied by evidence of cortical hyperperfusion and recovery of second- and third-order neurons along the involved circuit.

Hippocampal signal abnormality on the first day of illness in acute encephalopathy with biphasic seizures and late reduced diffusion caused by HHV-6 infection

We report a 13-month-old girl who developed acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) with transient reduced diffusion in the hippocampus and anterior commissure on diffusion-weighted imaging (DWI), which was performed on the first day after febrile status epilepticus (FSE) as the initial neurological symptom of AESD. DWI just after late seizures showed high signal intensity lesions in both left hippocampus and anterior commissure, and left extratemporal and occipital subcortical white matter. HHV-6 DNA was positive in both blood and cerebrospinal fluid samples. DWI at two months after onset showed atrophy in the left mesial temporal lobe and extratemporal and occipital lobe without the signal abnormalities. Although it has been reported that magnetic resonance images tend to show no acute abnormality during the first two days in typical AESD, transient reduced diffusion could be found on the DWI performed on the first day of AESD.

Transient seizure-related MRI abnormalities in a child with primary Epstein-Barr virus infection

We describe the case of a 6-year-old girl with typical infectious mononucleosis syndrome complicated by clustered right hemiconvulsions and disturbed consciousness. Diffusion-weighted magnetic resonance imaging on admission demonstrated reduced diffusion in the left temporo-posterior cortex and pulvinar of the ipsilateral thalamus. Her neurological symptoms resolved completely by the next day, with complete disappearance of abnormal signal intensities on magnetic resonance imaging (MRI). Elevated cerebrospinal fluid interleukin (IL)-6 with normal IL-10 might indicate a neuroprotective role of IL-6 rather than injury. We concluded that the MRI abnormalities could have been due to the seizure activity itself rather than Epstein-Barr virus-associated encephalitis. The recognition of transient seizure-related MRI abnormalities may help in the diagnostic approach to MRI changes in suspected encephalopathy.