The spectrum of benign myoclonus of early infancy: Clinical and neurophysiologic features in 102 patients

Transient myoclonic state or transient myoclonic state with asterixis: A systematic review

Transient myoclonic state (TMS) is a rare type of myoclonic jerks occurring predominantly in the upper extremities involving the head and commonly associated with asterixis. The present study performed a systematic review of published articles on this condition. For this purpose, six databases were searched by two reviewers to identify reports on TMS published online until November, 2024. A total of 17 reports containing 78 cases were found. Almost all the reports were from Japan, apart from one case reported in the USA. The mean age of the patients was 75.67 years (standard deviation, 5.8 years) and the median age was 75 years (range, 54 to 84 years). Sex was reported in 74 reports, and 60.8% of the patients were males. A precipitating factor, such as an infectious disease or the introduction of a new medication was observed in 24 cases (30.7%). All individuals achieved full recovery; however, 53 patients (67.9%) required benzodiazepine therapy, while the remaining individuals improved spontaneously. In summary, the present systematic review demonstrates that TMS is a rare condition, and is mainly encountered in Japan by unknown factors. There are likely genetic and environmental factors involved in its development; however, no specific geolocation related to the occurrence of TMS in Japan was found. It has a benign course and usually improves with the prescription of benzodiazepines. Management strategies include ensuring adequate multidisciplinary care coordination, as well as educating patients and their families about TMS. Future studies are required to describe the cases of TMS, including videos of the phenomenology. It is also recommended to perform whole genome sequencing analysis in patients with TMS.

Electroclinical Features of Infantile Epileptic Spasms Syndrome

Epileptic spasms are a unique, age-dependent manifestation of epilepsies in infancy and early childhood, commonly occurring as part of infantile epileptic spasms syndrome. Developmental stagnation and subsequent decline may occur in children with epileptic spasms, partly due to the abundant high-amplitude interictal epileptiform and slow wave abnormalities. Early recognition and treatment of epileptic spasms, along with the reversal of the electroencephalography (EEG) findings, are critical for improving outcomes. Recognizing hypsarrhythmia and its variations is key to confirming the diagnosis. The various patterns of hypsarrhythmia are not etiology specific, but could indicate the severity of the disease. Several scoring systems have been proposed to improve the inter-rater reliability of recognizing hypsarrhythmia and to assess EEG progress in response to treatment. Ictal patterns during spasms are brief and composed of slow waves, sharp transients, fast activity, and voltage attenuation, either in isolation or more commonly as a combination of these waveforms. Ictal patterns are commonly diffuse, but may be lateralized to one hemisphere in children with structural etiology. A subset of patients with epileptic spasms has a surgically remediable etiology, with readily identifiable lesions on neuroimaging in most cases. Asymmetry in epileptic spasms, concurrent focal seizures, and asymmetric interictal and ictal EEG findings may be present, but a lack of focality in electrophysiological findings is not uncommon. Intracranial EEG features of epileptic spasms have been described, but the utility of intracranial EEG monitoring in surgical candidates with overt focal epileptogenic lesions on magnetic resonance imaging is questionable, and surgery could be performed using noninvasive data.

Myoclonus: Differential diagnosis and current management

Myoclonus classically presents as a brief (10-50 ms duration), non-rhythmic jerk movement. The etiology could vary considerably ranging from self-limited to chronic or even progressive disorders, the latter falling into encephalopathic pictures that need a prompt diagnosis. Beyond the etiological classification, others evaluate myoclonus' body distribution (i.e., clinical classification) or the location of the generator (i.e., neurophysiological classification); particularly, knowing the anatomical source of myoclonus gives inputs on the observable clinical patterns, such as EMG bursts duration or EEG correlate, and guides the therapeutic choices. Among all the chronic disorders, myoclonus often presents itself as a manifestation of epilepsy. In this context, myoclonus has many facets. Myoclonus occurs as one, or the only, seizure manifestation while it can also present as a peculiar type of movement disorder; moreover, its electroclinical features within specific genetically determined epileptic syndromes have seldom been investigated. In this review, following a meeting of recognized experts, we provide an up-to-date overview of the neurophysiology and nosology surrounding myoclonus. Through the dedicated exploration of epileptic syndromes, coupled with pragmatic guidance, we aim to furnish clinicians and researchers alike with practical advice for heightened diagnostic management and refined treatment strategies. PLAIN LANGUAGE SUMMARY: In this work, we described myoclonus, a movement characterized by brief, shock-like jerks. Myoclonus could be present in different diseases and its correct diagnosis helps treatment.

Early-onset spontaneously relieved spasms of infancy in sleep: Electroclinical characteristics and differential diagnoses

PURPOSE

Infantile spasm-like paroxysms are often difficult to classify as epileptic or non-epileptic. We aimed to study spontaneously relieved (non-epileptic) spasms of infancy in sleep. Elucidation of the electroclinical characteristics and differential diagnoses of such spasms could facilitate accurate diagnosis in the future.

METHODS

We retrospectively analyzed the clinical data, video-EEG recordings, and other laboratory test results of patients with spontaneously relieved spasms of infancy during sleep. All the enrolled patients were followed up for at least 5 months.

RESULTS

Seven infants were included in this study. The median age at spasm onset was 0.5 months (range: 0.1-2 months). The episodes were characterized by clusters of non-epileptic spasms of the head, trunk, or extremities lasting approximately 0.5-2 s, and were validated by ictal electromyography (EMG)/video EEG. Episodes occurred several times daily in clusters, particularly during sleep; two patients also experienced episodes while awake. Additionally, non-epileptic jerks were recorded in 3 patients. All non-epileptic spasms were completely resolved 2 weeks to 3 months after onset. Moreover, neuropsychomotor development in all patients was normal at the last follow-up (5 to 12 months).

CONCLUSIONS

Spontaneously relieved spasms of infancy in sleep is a self-limiting movement disorder characterized by onset between 0.1 and 2 months of age, and by clusters of spasms occurring in sleep. Correct differential diagnosis relies on familiar clinical and electrophysiological features.

Role of Video-EEG in Children

Routine electroencephalogram (EEG) has many limitations, especially the inability to capture reported habitual events in question. A prolonged EEG with synchronized video (video-EEG) overcomes some of these limitations by improving the sensitivity, specificity and the diagnostic yield by attempting to record the habitual events when they are frequent and when indicated. Video-EEG is employed commonly for the diagnosis and classification of epilepsy/epilepsy syndromes, to distinguish between seizures and seizures mimickers, for pre-surgical evaluation and in the management of critically ill children. The duration of recording would vary depending on the indication and frequency of events. Ambulatory EEG is another cost effective and convenient alternative in certain circumstances. However, availability of the machines and expertise, accessibility, affordability and labor intensive nature of the procedure limit widespread use in India. This review explores the role of video-EEG in the management of children with epileptic and non-epileptic paroxysmal events with respect to routine clinical practice in India.

Repetitive sleep starts: An important differential diagnosis of infantile spasms

OBJECTIVE

Repetitive sleep starts (RSS) are clusters of nonepileptic, spasm-like movements occurring during sleep onset. However, their characteristics have yet to be defined. We conducted a clinicoelectroencephalographic study of children with RSS to clarify their detailed characteristics.

METHODS

To differentiate starts from epileptic spasms, we recruited children with brief "crescendo-decrescendo" muscle contractions that simultaneously involved the limbs and trunk without electroencephalogram changes, and that fulfilled the following criteria: (1) repeated occurrence (five or more) and (2) manifestation during sleep stage N1-N2. A total of nine children met these criteria. Their clinical information and video-electroencephalogram data were analyzed retrospectively.

RESULTS

The background conditions observed at onset of RSS were perinatal hypoxic-ischemic encephalopathy (n = 4), West syndrome of unknown etiology (n = 1), and traumatic brain injury (n = 1). The age at onset of RSS, the number of starts in a given RSS cluster, the interval between starts, and the duration of surface electromyogram activity were between 3 and 46 months, 5 and 547, <1 and 60 s, and 0.3 and 5.4 s, respectively. None of the median value of these parameters differed between children with and without corticospinal tract injury. During the median follow-up period of 33 months, RSS disappeared spontaneously in five.

CONCLUSION

This is the largest case series of RSS clarifying their clinicoelectroencephalographic characteristics reported to date. To avoid unnecessary antiepileptic therapies, clinicians should be aware of RSS and distinguish it from other disorders involving involuntary movements or seizures, especially epileptic spasms.

Is it really a seizure? The challenge of paroxysmal nonepileptic events in young infants

Paroxysmal nonepileptic events (PNE) comprise of a variety of nonepileptic behaviors and are divided into various types. A more accurate diagnosis is possible by examining the video clip provided by the caregiver. In infants, physiologic PNE accounts for the majority of the PNE. It is important to exclude epilepsy, for which blood tests, electroencephalography, and imaging tests can facilitate differential diagnosis. Since most PNE have a benign progress, symptoms often improve with age and without special treatment. Therefore, it is important to reassure the caregivers after making an accurate diagnosis.

Non-epileptic paroxysmal events in paediatric patients: A single tertiary centre study in Egypt

PURPOSE

The misdiagnosis of non-epileptic seizures (NES) as epilepsy is one of the most common pitfalls in neuropsychiatric practice. This study aimed to describe the percentage and types of NES among children who were referred for a diagnosis of epilepsy in Upper Egypt.

METHODS

We recruited a total of 876 patients who were referred to Sohag University Hospital, a tertiary referral centre in Upper Egypt, for the evaluation of suspected epilepsy. Relevant methods for the diagnosis of epilepsy, including medical history and examination, EEG, video-EEG, laboratory investigations, and brain imaging, were performed for all study participants.

RESULTS

Among the 876 patients who were referred for the diagnosis of suspected epilepsy during the period from June 2017 to October 2018, 171 patients (19.5 %) were diagnosed as having NES. In general, we found that NES in the paediatric age groups did not differ from that reported in various studies across several different populations. The most prevalent NES in our study was breath-holding spells (32.2 %), followed by syncope (17.5 %), psychogenic nonepileptic seizures (12.3 %), motor tics (9.9 %), and benign sleep myoclonus (7.6 %). Other less frequent NES included infantile masturbation (7 %), spasmus nutans (5.3 %), migraine (2.9 %), benign paroxysmal torticollis (2.9 %), night terrors (1.8 %), and shuddering attacks (0.6 %).

CONCLUSION

Ideally, neurologists should not misdiagnose NES as epilepsy, and whenever the diagnosis of NES is uncertain, an accurate diagnosis should be made using long-term video-EEG monitoring, especially in younger paediatric patients.

Management of Infantile Spasms During the COVID-19 Pandemic

Circumstances of the COVID-19 pandemic have mandated a change to standard management of infantile spasms. On April 6, 2020, the Child Neurology Society issued an online statement of immediate recommendations to streamline diagnosis and treatment of infantile spasms with utilization of telemedicine, outpatient studies, and selection of first-line oral therapies as initial treatment. The rationale for the recommendations and specific guidance including follow-up assessment are provided in this manuscript. These recommendations are indicated as enduring if intended to outlast the pandemic, and limited if intended only for the pandemic health care crisis but may be applicable to future disruptions of health care delivery.

Clinical and Genetic Overview of Paroxysmal Movement Disorders and Episodic Ataxias

Paroxysmal movement disorders (PMDs) are rare neurological diseases typically manifesting with intermittent attacks of abnormal involuntary movements. Two main categories of PMDs are recognized based on the phenomenology: Paroxysmal dyskinesias (PxDs) are characterized by transient episodes hyperkinetic movement disorders, while attacks of cerebellar dysfunction are the hallmark of episodic ataxias (EAs). From an etiological point of view, both primary (genetic) and secondary (acquired) causes of PMDs are known. Recognition and diagnosis of PMDs is based on personal and familial medical history, physical examination, detailed reconstruction of ictal phenomenology, neuroimaging, and genetic analysis. Neurophysiological or laboratory tests are reserved for selected cases. Genetic knowledge of PMDs has been largely incremented by the advent of next generation sequencing (NGS) methodologies. The wide number of genes involved in the pathogenesis of PMDs reflects a high complexity of molecular bases of neurotransmission in cerebellar and basal ganglia circuits. In consideration of the broad genetic and phenotypic heterogeneity, a NGS approach by targeted panel for movement disorders, clinical or whole exome sequencing should be preferred, whenever possible, to a single gene approach, in order to increase diagnostic rate. This review is focused on clinical and genetic features of PMDs with the aim to (1) help clinicians to recognize, diagnose and treat patients with PMDs as well as to (2) provide an overview of genes and molecular mechanisms underlying these intriguing neurogenetic disorders.

Transient benign paroxysmal movement disorders in infancy

This review summarizes the current empirical and clinical literature on benign paroxysmal movement disorders in infancy most relevant to practitioners. Paroxysmal benign movement disorders are a heterogeneous group of movement disorders characterized by their favourable outcome. We pay special attention to the recognition and management of these abnormal motor conditions strongly suggestive of epileptic disorders. They include: neonatal jitteriness; benign neonatal sleep myoclonus; benign paroxysmal tonic upgaze; paroxysmal tonic downgaze, benign paroxysmal torticollis and benign polymorphous movement disorder of infancy.

Reflex Myoclonic Epilepsy of Infancy: Seizures Induced by Tactile Stimulation

Myoclonic epilepsy with reflex seizures in infancy is an extremely rare condition, in which seizures are provoked mainly by auditory or auditory-tactile stimuli. To increase the awareness of pediatricians regarding this underrecognized condition, we describe a child with seizures provoked only by the tactile stimulation of specific areas of the head and face.

Intermittent head drops: the differential spectrum

Intermittent Head Drops are episodic head flexion movements that can occur in a number of conditions. Typically, the term has mainly been related to epileptic episodes, but the spectrum of clinical conditions associated with this feature is wide-ranging even if never discussed in detail. By searching the electronic database, we may find that apart from the epileptic conditions, Intermittent Head Drops have been in fact reported in the setting of movement disorders, sleep disorders and even internal medicine disorders, such as Sandifer syndrome. We render an in-depth description of this characteristic phenomenon in different diseases, describing the clinical clues and neurophysiological patterns that may help the clinician to distinguish between the different settings of occurrence.

Clinical management of epileptic encephalopathies of childhood and infancy

Epileptic encephalopathies represent a group of devastating epileptic disorders that appear early in life and are characterized by pharmacoresistant generalized or focal seizures, persistent severe EEG abnormalities, and cognitive dysfunction or decline. The ictal and interictal epileptic discharges are age-specific and are either the main cause or contribute to cognitive deterioration in the idiopathic or symptomatic group respectively. Despite choosing the most appropriate anti-seizure drugs for the seizure-type and syndrome the results are often disappointing and polytherapy and/or alternative therapy becomes unavoidable. In those cases, consideration should be given to the quality of life of the child and carers. In this review we will discuss the clinical and EEG characteristics, evolution and management of age-related epileptic encephalopathies, recognized by the International League Against Epilepsy.

A child with benign neonatal jitteriness and spasmus nutans

This patient, a 26-month-old girl, developed benign neonatal jitteriness soon after birth that subsequently resolved at 3 months of age. At 6 months of age, she developed spasmus nutans with left monocular nystagmus and head shaking in a "no-no" pattern. Physical examination was otherwise unremarkable. Magnetic resonance imaging (MRI) of the brain, optic nerves, and orbits was normal. The spasmus nutans also gradually resolved by 18 months of age. To our knowledge, the co-occurrence of these 2 benign movement disorders in an individual has not previously been reported. The pathogenesis of benign neonatal jitteriness and spasmus nutans is unknown. Their co-occurrence may reflect a shared underlying mechanism.

Syncopes and other paroxysmal events

Paroxysmal nonepileptic disorders are very frequent in infants and children and pediatric neurologists need to be as familiar with them as with epileptic seizures. Syncopes are the most important of these episodic disorders and amongst the syncopes the various subtypes of so-called neurally mediated syncopes (vagal, vasovagal, and so forth) predominate. In such syncopes there is almost always a trigger or provoking situation and this is the major clinical clue to the diagnosis. Whatever the mechanism of a syncope it is commonly "convulsive" in that there is a motor element, with tonic extensions and arrhythmic nonepileptic spasms ("jerks"). This everyday situation must be distinguished from the much less common combination of a syncope and a true epileptic seizure. In such anoxic-epileptic seizures the epileptic component is usually clonic, with rhythmic or semi-rhythmic jerks quite different from the arrhythmic spasms of the usual nonepileptic convulsive syncope. Syncope from compulsive Valsalva maneuver may be extremely frequent in affected (usually autistic) children. Diagnosis is easy if one obtains a video recording with audio: the premonitory hyperventilation stops leaving 11 seconds of silence before the tonic extension that signifies the syncope. Syncopes of more serious kind include those in long QT syndrome, hyperekplexia, paroxysmal extreme pain disorder, and congenital myasthenia; each has recognizable characteristics. Other nonsyncopal nonepileptic paroxysmal disorders are described further in the text.

Epileptic encephalopathies (including severe epilepsy syndromes)

Epileptic encephalopathies represent a group of devastating epileptic disorders that appear early in life and are characterized by pharmacoresistant generalized or focal seizures, persistent severe electroencephalography (EEG) abnormalities, and cognitive dysfunction or decline. The ictal and interictal epileptic discharges are age-specific and are the main etiologic factors causing cognitive deterioration. This is most obvious in the idiopathic group. In the symptomatic group, the most common causes are structural, congenital, or acquired and rarely some metabolic disorders. In certain cases, clinical and EEG abnormalities persist and may evolve from one type to another as the child grows older. Various factors trigger and sustain the underlying pathophysiologic process and the ongoing epileptic and epileptiform activity during the most critical periods of brain maturation, perpetuating their deleterious effect on the brain. Immune-mediated mechanisms may have a role, suggested by certain encephalopathies responding to immune-modulating treatments and by the finding of various autoimmune antibodies. The chance of a better cognitive outcome improves with early diagnosis and treatment that is appropriate and effective. Current antiepileptic drugs are, in general, not effective: we urgently need new trials in this very special epileptic category. This article briefly reviews the most common epileptic encephalopathies and analyzes the most important clinical issues.

Paroxysmal non-epileptic motor events in childhood: a clinical and video-EEG-polymyographic study

AIM

The aim of this article was to describe the phenomenology and polymyographic features of paroxysmal non-epileptic motor events (PNMEs) observed in a series of typically developing and children with neurological impairment.

METHOD

We conducted a retrospective evaluation of 63 individuals (29 females; 34 males) affected by PNMEs at the National Neurological Institute 'C. Besta' between 2006 and 2008. Individuals were included in the study if they had PNMEs documented by a video-electroencephalography-polymyographic study and were aged between 1 month and 18 years (mean age at the time of video-electroencephalography-polymyography: 5y 10mo).

RESULTS

In 45 of the 63 participants (71%), PNMEs were associated with other neurological conditions (secondary) including epilepsy, whereas in 18 participants PNME was the only neurological symptom (primary). Clinical features allowed classification of the motor disturbance into usual movement disorder categories in 31 individuals (49%); in the remaining 32 (51%), the movement disorder was characterized on the basis of polymyographic pattern of 'jerks' or 'sustained contraction'. The most frequent PNMEs were paroxysmal dyskinesias, followed by startle, stereotypies, shuddering, sleep myoclonus, psychogenic movement disorders, and benign myoclonus of early infancy; the last syndrome was also observed in children with neurological impairment. In eight participants, PNMEs remained unclassified.

INTERPRETATION

PNMEs may occur in both healthy and children with neurological impairment and are caused by a wide range of static and progressive conditions. In the majority of children with neurological impairment with associated epilepsy, the PNMEs do not fit into the usual movement disorders categories. A video-electroencephalography-polymyography is therefore useful for characterizing them.

Benign convulsions in newborns and infants: occurrence, clinical course and prognosis

BACKGROUND

During early development severe epilepsies may appear, some with well established occurrence. Benign non-epileptic and epileptic paroxysmal syndromes with excellent prognosis occur in the same period. There are no exact data on their occurrence.

AIM

We have reviewed medical histories of children with benign non-epileptic or benign epileptic events: benign myoclonus of early infancy, benign neonatal sleep myoclonus, benign sleep myoclonus in infancy, benign partial epilepsy in infancy (BPEI) and benign infantile familial convulsions (BIFC) were established. The occurrence, clinical characteristics and prognosis of these syndromes were evaluated.

METHODS

Inclusion criteria were met in 31 children. Research included retrospective analysis of clinical characteristics, laboratory values, neuroimaging and neurophysiological assessments, followed by evaluation of psychosocial development with the use of the Strengths and Difficulties Questionnaire (SDQ), fulfilled by parents.

RESULTS

In our group the incidence of benign non-epileptic convulsions was 6.69 per 10 000 live births and the incidence of benign epileptic convulsions was 1.35 per 10 000. Male/female ratio in the group of children with non-epileptic events was 2.1:1. Among non-epileptic group 5 out of 23 children and among epileptic group 3 out of 8 children had minimal, mild or moderate abnormalities at neurological assessment at the time of the first clinical examination. Nonspecific changes in laboratory values were seen in 6 out of 23 in the non-epileptic and in 1 out of 8 children in the epileptic group. Neurophysiological assessments showed subtle changes in 4/23 in the non-epileptic and 6/8 in the epileptic group. Neuroimaging was not optimal in 5/23 with non-epileptic and 3/8 with epileptic events. Analysis of SDQ did not show significant deviations in psyhosocial development. Statistically significant deviation was observed only in relations with peers (p = 0.009).

CONCLUSIONS

Benign neonatal and infantile convulsions are more frequent than severe epilepsies of the same age period. Results show higher proportion of males with benign non-epileptic conditions. No deviations in further development was found. Laboratory values, neuroimaging and neurophysiological assessments were normal or nonspecifically changed.