Reversible focal MRI abnormalities due to status epilepticus. An EEG, single photon emission computed tomography, transcranial Doppler follow-up study

Seizure-induced reversible MRI abnormalities in status epilepticus: A systematic review

In the context of status epilepticus (SE), seizure-induced reversible MRI abnormalities (SRMA) can be difficult to differentiate from epileptogenic pathologies. To identify patterns and characteristics of SRMA, we conducted a systematic review in accordance with the Preferred Items Reporting for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We included publications describing patients (a) presenting with status epilepticus, (b) exhibiting seizure-induced MRI abnormalities, (c) who demonstrated complete resolution of MRI abnormality at follow-up, and (d) who had availability of descriptive MRI results. A total of 49 cases from 19 publications fulfilled our eligibility criteria. Signal abnormalities were most frequently reported on T2-weighted sequences followed by diffusion-weighted and fluid-attenuated inversion recovery imaging. Both unilateral and bilateral SRMA were reported. Unilateral EEG abnormalities were often associated with ipsilateral SRMA. The signal changes appeared during the ictus itself in some subjects whilst the median time to SRMA appearance and resolution were 24 h and 96.5 days, respectively. Based on the distribution of reversible signal alterations, we identified five 'composite patterns': (1) predominant cortical (with or without subcortical, leptomeningeal or thalamic involvement), (2) hippocampal (with or without cortical, subcortical, leptomeningeal, or thalamic involvement), (3) claustrum, (4) predominant subcortical, and (5) splenium involvement. Amongst treatment-responsive SE patients, the cortical pattern was the most prevalent whereas hippocampal involvement was most frequently reported in refractory SE. Cortical atrophy, hippocampal sclerosis, and cortical laminar necrosis were common long-term sequelae after the resolution of SRMA. In this review, we highlight many limitations of the literature and discuss future directions for research.

Post-Traumatic Status Epilepticus Masquerading as Acute Ischemic Stroke: A Case Report and Literature Review

Patient: Male, 7-year-old

Final Diagnosis: Status epilepticus

Symptoms: Local sezure

Medication: —

Clinical Procedure: Computed tomography • magnetic resonance imaging

Specialty: Neurosurgery

Focal Status Epilepticus-Related Unilateral Brain Edema: Magnetic Resonance Imaging Study of Children in Southwest China

BACKGROUND

Unilateral brain edema is a rare peri-ictal imaging abnormality related to focal status epilepticus. We present the largest series of these patients, describe their clinical features and magnetic resonance imaging (MRI) findings, and analyze the possible underlying pathophysiology.

METHODS

We reviewed the medical records in Southwest China's largest tertiary's children's medical center from 2011 to 2017. Patients with focal status epilepticus were included if acute-phase cerebral MRI showed unilateral edematous swelling of the epileptic hemisphere.

RESULTS

Eleven children were included. The age at which the patients presented with status epilepticus ranged from seven months to 10.8 years. All patients showed prolonged clonic seizures with marked unilateral predominance followed by hemiplegia of the ipsilateral limbs. The seizure duration ranged from one to 72 hours. All patients showed hyperintensities on T2-weighted images and diffusion-weighted images involving the whole pathologic hemisphere. Three patients showed involvement of the contralateral cerebellar hemisphere and one showed hippocampal herniation. Magnetic resonance angiography of the brain was performed in seven patients, among which three showed dilation of the affected hemispheric arteries. Three patients underwent follow-up MRI, and all the examinations revealed ipsilateral cerebral hemisphere atrophy.

CONCLUSIONS

Focal status epilepticus may cause unilateral brain edema, and cytotoxic edema probably plays an important role in the pathophysiology of brain injury.

Status epilepticus in dogs and cats, part 1: etiopathogenesis, epidemiology, and diagnosis

OBJECTIVE

To review current knowledge of the etiopathogenesis, diagnosis, and consequences of status epilepticus (SE) in veterinary patients.

DATA SOURCES

Human and veterinary literature, including clinical and laboratory research and reviews.

ETIOPATHOGENESIS

Status epilepticus is a common emergency in dogs and cats, and may be the first manifestation of a seizure disorder. It results from the failure of termination of an isolated seizure. Multiple factors are involved in SE, including initiation and maintenance of neuronal excitability, neuronal network synchronization, and brain microenvironmental contributions to ictogenesis. Underlying etiologies of epilepsy and SE in dogs and cats are generally classified as genetic (idiopathic), structural-metabolic, or unknown.

DIAGNOSIS

Diagnosis of convulsive SE is usually made based on historical information and the nature of the seizures. Patient specific variables, such as the history, age of seizure onset, and physical and interictal neurological examination findings can help hone the rule out list, and are used to guide selection and prioritization of diagnostic tests. Electroencephalographic monitoring is routinely used in people to diagnose SE and guide patient care decisions, but is infrequently performed in veterinary medicine. Nonconvulsive status epilepticus has been recognized in veterinary patients; routine electroencephalography would aid in the diagnosis of this phenomenon in dogs and cats.

CLINICAL SEQUELAE

Status epilepticus is a medical emergency that can result in life-threatening complications involving the brain and systemic organs. Status epilepticus often requires comprehensive diagnostic testing, treatment with multiple anticonvulsant agents, and intensive supportive care.

Cognitive tasks and cerebral blood flow through anterior cerebral arteries: a study via functional transcranial Doppler ultrasound recordings

Background

Functional transcanial Doppler ultrasound (fTCD) is a convenient approach to examine cerebral blood flow velocity (CBFV) in major cerebral arteries.

Methods

In this study, the anterior cerebral artery (ACA) was insonated on both sides, that is, right ACA (R-ACA) and left ACA (L-ACA). The envelope signals (the maximum velocity) and the raw signals were analyzed during cognitive processes, i.e. word-generation tasks, geometric tasks and resting state periods separating each task. Data which were collected from 20 healthy participants were used to investigate the changes and the hemispheric functioning while performing cognitive tasks. Signal characteristics were analyzed in time domain, frequency domain and time-frequency domain.

Results

Significant results have been obtained through the use of both classic/modern methods (i.e. envelope/raw, time and frequency/information-theoretic and time-frequency domains). The frequency features extracted from the raw signals highlighted sex effects on cerebral blood flow which revealed distinct brain response during each process and during resting periods. In the time-frequency analysis, the distribution of wavelet energies on the envelope signals moved around the low frequencies during mental processes and did not experience any lateralization during cognitive tasks.

Conclusions

Even if no lateralization effects were noticed during resting-state, verbal and geometric tasks, understanding CBFV in ACA during cognitive tasks could complement information extracted from cerebral blood flow in middle cerebral arteries during similar cognitive tasks (i.e. sex effects).

Diffusion MR imaging for monitoring treatment response

The objective of this article was to emphasize the use of diffusion-weighted imaging in the diagnosis and follow-up of several major disease contexts, as established in recent literature. In some of these diseases the diffusion changes are correlated with the clinical deficit and are potentially useful for early diagnosis and longitudinal evaluation, as well as in the context of pharmacologic trials. Diffusion magnetic resonance is a major advance in the continuing evolution of MR imaging. It provides contrasts and characterization between tissues at a cellular level that may imply differences in function as well as framework and have contributed to a better understanding of the pathophysiological mechanisms of several diseases.

The electroclinical-imagiological spectrum and long-term outcome of transient periictal MRI abnormalities

The electroclinical-imagiological spectrum and long-term outcome of transient periictal MRI abnormalities (TPMA) remains largely unclear. This prompted us to perform a prospective observational cohort study, including electroencephalography (EEG) and multi-sequence MRI, in 19 consecutive patients (8 female, mean age 51.7 years) with TPMA induced by convulsive and non-convulsive status epilepticus (n=14) or isolated seizures. TPMA were associated with focal, lateralized or diffuse EEG abnormalities, and were mostly focal unilateral and cortico-subcortical (n=11), less frequently cortically restricted, bilateral, hemispheric and with remote lesions (pulvinar, cerebellum); 66.7% had cortico-pial contrast enhancement and 93.7% restriction on diffusion-weighted imaging, with cortical cytotoxic edema on apparent-diffusion coefficient, only tumor-like TPMA (n=5) presenting noticeable subcortical vasogenic edema. The heterogeneity of clinical, EEG and MRI findings contributed to a 38.6% strict focal topographic concordance between them, with the more widespread findings also attributable to the time lag between studies, seizure dynamics/etiologies and cerebral reserve. At follow-up (mean duration 29.6 months, 3-120), the brain damage induced by TPMA was responsible for a high incidence of clinical and MRI sequelae (63.2%), only tumor-like/small TPMA induced by acute symptomatic seizures presenting good clinical outcomes. Our findings may contribute to a better definition and comprehension of the TPMA electroclinical-imagiological spectrum, pathophysiology and long-term outcome.

Hippocampal sclerosis and status epilepticus: cause or consequence? A MRI study

BACKGROUND

Transient imaging abnormalities, including changes on diffusion-weighted imaging (DWI), may be seen in status epilepticus. These abnormalities can be followed by hippocampal sclerosis.

CASE REPORT

We report a 15-year-old lady with focal non convulsive status epilepticus (NCSE) and focal slowing on EEG. DWI exhibited abnormal hyperintense signals in bilateral temporal and insular cortices. After 3 weeks, MRI performed a localizated hippocampal atrophy.

CONCLUSION

The MRI findings indicated vasogenic and cytotoxic edema during seizure activity and subsequent loss of brain parenchyma.

Seizure-associated Abnormalities in Epilepsy: Evidence from MR Imaging

Acute seizure-associated changes have been described in the animal and human literature. Controversy exists over whether seizures cause permanent damage to the brain, and whether a (prolonged) seizure can induce changes that lead to an epileptic lesion, resulting in habitual seizures and epilepsy. Current magnetic resonance imaging (MRI) offers a variety of imaging tools and is capable of detecting acute seizure-associated changes. In contrast to the histologic examination, serial MRI studies are possible and allow longitudinal observation of the fate of these changes. This report reviews the literature on acute seizure-associated effects emphasizing the MRI evidence.

Cerebral autoregulation improves in epilepsy patients after temporal lobe surgery

Patients with temporal lobe epilepsy (TLE) often show increased cardiovascular sympathetic modulation during the interictal period, that decreases after epilepsy surgery. In this study, we evaluated whether temporal lobectomy changes autonomic modulation of cerebral blood flow velocity (CBFV) and cerebral autoregulation. We studied 16 TLE patients 3-4 months before and after surgery. We monitored heart rate (HR), blood pressure (BP), respiration, transcutaneous oxygen saturation (sat-O(2)), end-expiratory carbon dioxide partial pressure (pCO(2)) and middle cerebral artery CBFV. Spectral analysis was used to determine sympathetic and parasympathetic modulation of HR, BP and CBFV as powers of signal oscillations in the low frequency (LF) ranges from 0.04-0.15Hz (LF-power) and in the high frequency ranges from (HF) 0.15-0.5Hz (HF-power). LF-transfer function gain and phase shift between BP and CBFV were calculated as parameters of cerebral autoregulation. After surgery, HR, BP(mean), CBFV(mean), respiration, sat-O(2), pCO(2) and HF powers remained unchanged. LF-powers of HR, BP, CBFV and LF-transfer function gain had decreased while the phase angle had increased (p<0.05). The reduction of LF powers and LF-gain and the higher phase angle showed reduced sympathetic modulation and improved cerebral autoregulation. The enhanced cerebrovascular stability after surgery may improve autonomic balance in epilepsy patients.

Single-photon emission computed tomography in a patient with ictal metamorphopsia

Metamorphopsia is a type of visual illusion, which has been reported as a rare ictal manifestation. The patient presented with a simple partial status epilepticus characterised by continuous facial metamorphopsia, intermittently accompanied by elementary visual hallucinations or other types of visual illusions. Subtraction single-photon emission computed tomography images showed an increased perfusion in the ventrolateral aspect of the right temporo-occipital junction (middle and inferior occipital, and inferior temporal gyri). The result suggests that the anatomical substrate involved in the generation of ictal facial metamorphopsia is located in the visual association areas at the right temporo-occipital junction.

Risk factors of status epilepticus in children

BACKGROUND

Although there is abundant literature about the morbidity and mortality rates of status epilepticus (SE), little is known about the risk factors of this medical emergency. The aim of the present study is to assess the risk factors of SE in children.

METHODS

The authors reviewed the medical records of 83 patients admitted to the Pediatric Neurology Unit of Trakya University Hospital, Edirne, Turkey from January 1994 to December 2001 with the diagnosis of SE. Eighty-three patients were compared with 166 controls who were admitted to the same unit due to non-status epilepticus (non-SE) seizure.

RESULTS

The univariate analysis demonstrated that SE episodes were significantly associated with a history of birth asphyxia, neonatal seizure, discontinuation of antiepileptic medication, epilepsy, partial seizure evolving to secondary generalized seizures, myoclonic seizure, generalized abnormalities in the neurological examination, neuromotor retardation, generalized background abnormalities on electroencephalogram (EEG), generalized abnormalities on neuroimaging and polypharmacy than non-SE episodes. Logistic regression was used to test the independence of these parameters as predictors of SE risk. Four parameters emerged as significant independent predictors of SE in children in multiple logistic regression: polypharmacy (Odds ratio (OR) 5.17, P = 0.0004), discontinuation of antiepileptic medication (OR 4.04, P = 0.0095), neuromotor retardation (OR 4.03, P = 0.0016) and generalized background abnormalities on EEG (OR 2.48, P = 0.0419).

CONCLUSION

Polypharmacy, discontinuation of antiepileptic medication, neuromotor retardation and generalized background abnormalities on EEG are indicators in children of a higher risk of SE.

Status epilepticus and acute serial seizures in children

Status epilepticus is defined as a seizure that persists for a sufficient length of time or is repeated frequently enough to produce a fixed and enduring epileptic condition of 30 minutes or longer. Status epilepticus is a life-threatening condition that often occurs in children. The degree of mortality and neurologic morbidity, as well as the risk for recurrence, is highly dependent on the etiology and duration of the seizures. Although much has been written about pediatric status epilepticus, many issues remain unresolved. A better understanding of the different types of seizures and their etiologies may help in the prevention and treatment of status epilepticus. The vast extent of status epilepticus in both children and adults mandates that new options for prevention and treatment be given a close scrutiny and high priority. This article will review the most current information on convulsive and nonconvulsive status epilepticus, including the potential for neurologic damage, changes in magnetic resonance imaging after status epilepticus, risk for recurrence, and current treatment options available for treating status epilepticus in children.

Transient MRI abnormalities associated with partial status epilepticus: a case report

We report the case of an 18-year-old woman who presented a long-lasting cluster of partial seizures, and MRI cortical abnormalities localized in the left parietal lobe. The MRI changes correlated with the site of the epileptogenic focus, and disappeared within 2 weeks. The recognition of these reversible MRI abnormalities, which are presumably due to a temporary alteration of blood-brain barrier in the epileptogenic zone with subsequent edema, and are not associated with any underlying organic conditions, is extremely useful in the medical management of the patient and allows to avoid other invasive diagnostic procedures.

Long-term intra-individual variability of the background EEG in normals

OBJECTIVES

Forty-five healthy adult volunteers underwent repeated qEEG examinations with retest intervals 25-62 months in order to investigate the long-term intra-individual variability of several qEEG features such as, absolute and relative power, power asymmetry, coherence, mean and peak frequency and entropy. Prior to any computations all parameters were transformed to Z-scores on the basis of a normal database.

METHODS

Correlation coefficients were used to test the effect of the time on the test-retest differences. Correlation coefficients were also computed between baseline and retest values, as a measure of intra-individual stability, to make our results comparable to most literature data. By computing the standard deviations for test-retest differences, the intra-individual variabilities of the examined parameters were obtained in the unit of inter-individual variability of normal population. The same calculations were carried out with values obtained from the odd and even numbered epochs of the same EEG sections. This way, that portion of the intra-individual variability was estimated that might be introduced even by chance only when the epochs were selected randomly from the same section of EEG conforming to selection criteria.

RESULTS

As for our results, further increase of test-retest differences with time after 25 months might be so insignificant that it could not be demonstrated in our test material. The long-term intra-individual variability for most parameters, especially for total absolute power and alpha mean frequency, was less than the inter-individual variability in the normal population. The moment-to-moment variability was least in the case of the absolute power.

CONCLUSIONS

Estimates for intra-individual variability expressed this way in Z-scores might easily be used in the follow-up of patients even for a few years.