What Is Hypsarrhythmia, Symptom, Treatment – An Overview

Hypsarrhythmia Definition: Hypsarrhythmia is defined as continuous, arrhythmic, high-amplitude, asynchronous delta activities with interspersed substantive, multiple spikes -From: EEG Pearls, 2006

Introduction

Hypsarrhythmia is the commonest interictal EEG pattern associated with Hypsarrhythmia infantile spasms. The foremost common clinical description is a sudden, symmetric, tonic muscle contraction producing flexion/extension of the trunk and extremities, Therefore, although a variety of movement patterns have been mentioned. Furthermore, the normal EEG pattern is a chaotic mixture of high-amplitude slow waves, intrahemispheric-interhemispheric asynchrony, and multifocal spikes. This EEG pattern normally is observed in children three(3) months to five(5) years old, and therefore, it can be preceded by a burst-suppression or low-voltage invariant pattern in the newborn period. Furthermore, hypsarrhythmia EEG may also be preceded by a normal EEG pattern/ normal EEG reading. During a spasm, an electrodecremental response interrupts the high-amplitude slowing by a sudden diminution of all activity with a duration of one(1) second to one(1) minute. Therefore, the role of EEG is limited to diagnosis only, with no reliable correlation with cause, course, or prognosis, including mental development.

Therefore, hypsarrhythmia is a too chaotic and disorganized brain electrical activity with no observable/recognizable pattern. standard brain electrical activity shows a transparent separation between every signal and visible pattern. whereas it’s an abnormal interictal pattern, consisting of high-amplitude and spikes in a background of chaotic and irregular waves disorganized activity seen on an EEG (electroencephalogram), and frequently encountered in infants diagnosed with infantile spasms, although it may be found in other different conditions.

Gibbs & Gibbs represented hypsarrhythmia in 1952 as “random high voltage waves and spikes. Therefore, these spikes vary from moment to moment, both in time and in location. At the time they seem to be focal, and a couple of seconds later they appear to originate from multiple foci. often the spike discharge becomes generalized, but it never seems as a rhythmically repetitive and extremely organized pattern that might be confused with a discharge of the petit mal or petit mal variant type”.

In most cases of infantile spasms, hypsarrhythmia either disappears or improves throughout a cluster of spasms and/or REM sleep. therefore, hypsarrhythmia rarely persists beyond the age of twenty-four(24) months.

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Normal Vs Abnormal EEG

These pattern are very different from a normal EEG, as given below shown in these examples, Normal EEG and Hysarrhythmic EEG (i.e. EEg Normal, Abnormal EEG patterns, Abnormal EEG Reading, Normal EEG Results)

Hypsarrhythmia is a disorderly, chaotic pattern of brain waves that happen in kids with IS but not in other seizure disorders. Therefore, unlike spasms, which is not a symptom that you can see. It can only be detected by a noninvasive, painless test known as an EEG.

Because hypsarrhythmia is very important to the diagnosis of infantile spasms (IS), it is important to capture the pattern once it happens. A routine electroencephalogram (EEG), which may usually take a couple of hours, may not last long enough to do this successfully. Therefore, your doctor may order a 24-hour electroencephalogram (EEG) for your kid if he or she suspects IS. Furthermore, this is conducted while your kid is in the hospital and might be monitored continuously.

Purpose

Hypsarrhythmia is an electroencephalographic pattern related to epileptic spasms and West syndrome EEG. Therefore, the west syndrome EEG is a devastating epileptic encephalopathy and originating in infancy. thus, hypsarrhythmia has been understanding to be the interictal brain activity, so, while the electrodecremental response event related to the spasms is denoted as the ictal event. though characterized as chaotic, asynchronous, and disorderly based on visual examination of the electroencephalographic (EEG), little is known of the dynamics of hypsarrhythmia and Furthermore, how it impacts the developmental arrest of these infants.

Paroxysmal Disorders

Evaluation: EEG, MRI. The term hypsarrthmiain an electroencephalogram (EEG) report is specific for a diagnosis of infantile spasms. The hypsarrhythmic electroencephalogram pattern is a high-amplitude, chaotic slowing of generalized distribution while not interhemispheric synchronization and with multifocal epileptiform discharges throughout. Therefore, hypsarrhythmia is more frequent in younger infants and early in the course of the disorder, and it’s additionally common to search out some changed variant of it. In a child with a powerful clinical suspicion of infantile spasms, sleep should be captured in the EEG, as early in the course, the hypsarrhythmic pattern is evident during sleep.

Investigation of patients with infantile spasms is directed at determinative the cause and so determinative whether or not there’s an underlying genetic, structural, or metabolic etiology. Infantile spasms are caused by a large variety of neurologic insults; the most common etiologic factor in perinatal hypoxic-ischemic encephalopathy. Other necessary associations include intrauterine infection, intracranial hemorrhage, prematurity, malformations of cortical development, head injury, CNS infection, tuberous sclerosis, and inborn errors of metabolism. Therefore, If infantile spasms are seen in conjunction with agenesis of the corpus callosum and retinal abnormalities on eye examination, this suggests a diagnosis of Aicardi syndrome.

Almost ninety-five percent (95%) of the kid with an identified cause (genetic, structural, or metabolic) have a prognosis of moderate-to-severe neurologic injury, including refractory epilepsy, permanent developmental sequelae. or cognitive impairment.

Therefore, almost 10-15% of patients have no identifiable main cause and normal development before the onset of their illness and furthermore, this subset is referred to as idiopathic or cryptogenic, West syndrome. Furthermore, this subset of patients is eventual to have a much better long-term outcome: thirty-eight percent (38%) of these patients are mildly impaired, or normal in comparison with only 5% of symptomatic patients.

Furthermore, a unique subset of patients who can develop infantile spasms in kids with trisomy 21. Thus the incidence of infantile spasms in this group is 1-5%. furthermore, it has a genetic disorder and baseline neurologic abnormalities, these children have a high response rate to treatment with ACTH with rapid resolution of the abnormal hypsarrhythmia on EEG.

About fifty percent (50%) of infants go on to have other seizure types when spasms cease. Therefore, the persistence of epilepsy in the patients is related to loss of the spasms and development of other seizure types, such as tonic seizures, focal seizures, and tonic-clonic seizures. Approximately half of the children with Lennox-Gastaut syndrome, a combination of cognitive disability, generalized seizures, and a distinctive abnormal EEG pattern, have a history of infantile spasms. Therefore, the seizures similar in appearance to infantile spasms (tonic seizures occurring in clusters or brief myoclonic) can recur later in childhood, and these are referred to as epileptic spasms.

Classification:

Through the utilization of video electroencephalogram (EEG) and continuous observance, five variants of the “classical” hypsarrhythmic pattern have been identified:

• Hypsarrhythmia with increased interhemispheric synchronization. Characterized by synchronized and symmetric activity, seen in patients with longstanding evolution, particularly in those with West syndrome that changes to Lennox-Gastaut syndrome.
• Asymmetric hypsarrhythmia related to a brain structural abnormality and doesn’t necessarily predict the affected hemisphere.
• Hypsarrhythmia with a regular focus of abnormal discharge.
• Hypsarrhythmia with episodes of voltage attenuation. therefore, during nonrapid eye movement (NREM) sleep. once the episodes of voltage attenuation seem at the identical time as an epileptic spasm does, they’re referred to as electrodecrements.
• Hypsarrhythmia with a touch spike or sharp activity.

The “H” in PEHO syndrome stands for hypsarrhythmia.
Together with developmental regression and infantile spasms, hypsarrhythmia is one of the diagnostic criteria for West syndrome.

REFERENCES

1. Hypsarrhythmia EEG
2. Science Direct Article taken from the Hypsarrhythmia
3. Paroxysmal Disorders: Priya Monrad, in Nelson Pediatric Symptom-Based Diagnosis, 2018
4. Pediatric Neurophysiologic Evaluation: Mark S. Scher, in Swaiman’s Pediatric Neurology 6th Edition, 2017
5. Millichap, JJ; Millichap, JG (2015). “Hypsarhythmia or Hypsarrhythmia?”
6. “EEG in Common Epilepsy Syndromes: eMedicine Neurology”
7. “What is hypsarrhythmia Article Taken from Acthar GEL”