Article Type : Research Article
Authors : Kitchener N
Keywords : Nonconvulsive status epilepticus; Complex partial status epilepticus; Absence status; Petit mal status; Typical absence status epilepticus; NCSE; EEG
Introduction: The recognition of convulsive status
epilepticus is clinically apparent and easily diagnosed. However, the
recognition and diagnosis of non-convulsive status epilepticus (NCSE),
especially in children, is more troublesome and complicated.
Objective: Study aimed to define the NCSE syndrome, its
classification, and frequency of presentation, proposed etiology and
symptomatology.
Patients and Methods: A retrospective study of records of
112 children with the diagnosis of NCSE presented between June 2006 and
December 2020 were reviewed. Children were classified according to clinical
presentation, EEG pattern and neuroimaging results into a) Typical absence
NCSE, b) Atypical absence NCSE, c) Simple Partial NCSE, and d) Complex Partial
NCSE.
Results: Of the 112 Patients, 46 were males and 66 females.
Age ranged from 6.2-14 years. Clinically, 57% of the children suffer from
complex partial NCSE, 31% from atypical absence NCSE, 7% from typical absence
NCSE, and 5% from Simple Partial NCSE. Cryptogenic etiology is the most
frequent (47%), followed by vascular insults (18%).
Conclusion: Children have a higher risk of NCSE
than adults. In this study, most children are known epileptics; cerebrovascular
insults were the second frequent cause of NCSE, after cryptogenic. Clinical
suspicion, EEG, or long trace EEG permits early diagnosis and intervention.
The recognition of convulsive status epilepticus is
clinically obvious and easily diagnosed [1]. However, the recognition and
diagnosis of non-convulsive status epilepticus (NCSE), especially in children,
is more difficult [2-4]. The NCSE is often underdiagnosed or diagnosed late
because it requires a high index of suspicion and an electroencephalogram. The
fact that SE could consist of "delirium, stupor, or coma, cough, or hiccup
and a variety of psychic states which have their basis in critical EEG discharges
resulting in more or less complete physical or psychic exhaustion” [5,6].
Children with NCSE can present with variety of clinical manifestations
including coma, confusion, drowsiness, altered mood, fugue states, aphasia, or
vegetative abnormal autonomic symptoms, hallucinations, and paranoid behavior
[7]. All these symptoms should occur in the absence of evident convulsive
seizure activity (tonic, clonic or tonic-clonic). Despite the lack of
convulsive activity, NCSE is thought to result in neuronal injury, and so its
recognition and treatment is critical [8]. No consensus exists on the
phenomenology, nosology, and classification of NCSE. Some authors use the term
to describe all cases with altered sensorium without convulsive movements. The
EEG remains the most important investigative and diagnostic tool for confirming
NCSE.
Classified NCSE as following [9]:
Generalized Absence SE
•
Typical absence SE.
•
Atypical absence SE.
•
De novo absence SE of
late onset.
•
Absence SE in other
epileptic syndromes.
•
Partial
SE:
•
Non-convulsive
CPSE
•
Non-convulsive
simple partial SE
Boundary zones
•
Electrographic
SE
•
Prolonged postictal
confusional state
•
Episodic behavioral
disturbances and psychosis.
•
Clinical manifestations
•
The status usually occurs
in patients with idiopathic generalized epilepsy.
•
It lasts 12 hours or less
in over 50 % of patients but can persist for days, weeks or months.
•
An episode of TASE is
often terminated by an attack of a Tonic-clonic seizure.
•
About 20 % show slowing
of ideation and expression only.
•
The verbal functioning
may be well preserved as compared to CPSE. In 50 percent of patients there is
marked clouding of sensorium.
•
These patients are
immobile, able to perform simple tasks after repeated asking, and are often
mute or near mute with long delay in verbal response or with monosyllabic
answers.
•
The appearance is blank
or puzzled as if in a trance. About 50 percent of patients show subtle motor
features such as myoclonus, atonia, eyelid myoclonia, trembling of lips, facial
grimacing and smiling. The presence of symptoms like eyelid myoclonia,
myoclonus … etc. are useful clues in differentiating TASE from CPSE [9-11].
•
Occurs in patients with
secondary generalized epilepsies, particularly, of the Lennox Gastaut type, and
in other cryptogenic or symptomatic generalized syndromes, especially those
associated with mental handicap and cerebral damage (12).
•
This contrasts with TASE,
which occurs in individuals with normal mentality and neurological examination.
•
The clinical features of
atypical and typical absence SE may show considerable overlap at times.
•
Atypical SE, however,
shows some characteristics:
•
Episodes in atypical SE
are longer and more frequent,
•
The onset and offset are
more gradual; and are often preceded by changes in mood, motor activity for
hours or days before the status.
•
The status tends to
fluctuate, and may evolve into minor motor, myoclonic or tonic seizures.
•
Initiation or cessation
of atypical absence SE with a tonic clonic seizure is unusual [12-15].
•
In SPSE, there is no
alteration in awareness or responsiveness.
•
The location of the ictal
discharge determines the clinical manifestations, which may be sensory, psychic, or autonomic.
•
It may manifest as
•
prolonged unmotivated
fear,
•
Autonomic upset e.g.,
episodes of tachycardia, pupillary dilatation, and incontinence.
•
prolonged aphasia (due to
discharges arising from the left basal temporal language area), prolonged
blindness (status epilepticus amauroticus),
•
Visual hallucinations,
ictal hemiplegia.
•
Prominent psychic
symptomatology with severe autistic or schizophrenic features.
•
Although earlier studies
concluded that CPSE was rare; recent reports indicate that it is probably under
reported. It is possible that atypical absence SE being reported may in fact be
cases of CPSE.
•
Until recently, CPSE had
been equated with temporal lobe status epilepticus.
•
Seizure origin was
extratemporal in most of properly investigated patients.
•
Thus, CPSE is not
analogous with temporal lobe origin; on the contrary, extratemporal sites,
notably frontal lobe may often be the responsible site.
•
Aicardi observed that
bilateral continuous paroxysmal activity could occur in partial status,
especially with frontal lobe lesions making it resemble an absence SE.
•
CPSE is associated with a
wide variety of clinical patterns, which may be indistinguishable from those of
atypical absence SE.
•
Recurrent complex partial
seizures without full recovery of consciousness between seizures, or a
continuous “epileptic twilight state" with cycling between unresponsive
and partially responsive phases (lasting more than 30 Minutes).
•
Ictal EEG with recurrent
epileptiform patterns like those seen in complex partial seizures.
•
A prompt observable
effect of intravenous antiepileptics on both ictal EEG and clinical
manifestations of status.
•
Interictal EEG with a
consistent epileptiform focus.
•
The alteration in
sensorium can vary from bland confusion, either continuous or intermittent, to
agitated unresponsiveness with bizarre, almost psychotic activity (15,16,19)
•
Speech patterns are often
abnormal with perseveration, aphasia, echolalia, confabulation, or just slow
responses.
•
It may start with Motor
features in the form of adversive posturing, tonic posturing, and simple
automatisms.
•
Autonomic disturbances
include belching, flatulence, change in color, fever, or pupillary changes.
The objective of this study is to describe the
syndrome definition, classification, and its presentation frequency, proposed
etiology and symptomatology of pediatric patients with NCSE who attended the
Mataryia Teaching Hospital in the period between June 2006 and December 2020.
3583 children with or without behavioral changes, were
admitted during the period from June 2006 to December 2020 to El-Matryia
Teaching Hospital; those were admitted with disturbed levels of consciousness.
All patients with disturbed level of consciousness had thorough clinical
examination, routine laboratory investigations, and brain imaging, according to
the hospital routine protocol. Of the firstly reviewed 518 children cohort, who
had continuous EEG records for at least 12 hours (long trace EEG), 406 were
excluded due to either normal EEG record, or having either metabolic disorder
(e.g., diabetic ketoacidosis, hyperammonemia etc.), acute vascular brain insult
(cerebrovenous thrombosis, ischemic insult, hemorrhagic insult etc.), or Space
occupying lesions; the remaining 112 children with proven non-convulsive status
epilepticus (NCSE) represent the subjects of the current study. EEG recordings
were performed on 21 channel EEG instruments using the international 10–20
electrode system. Continuous EEG monitoring records lasting at least 12 h were
available for every patient. Thus, a retrospective study of records of the 112
children with the diagnosis of NCSE presented between June 2006 and December
2020 were fully analyzed; those children were classified, according to clinical
presentation, EEG pattern and neuroimaging results, into a) Typical absence
NCSE, b) Atypical absence NCSE, c) Simple Partial NCSE, and d) Complex Partial
NCSE.
3% of the admitted patients with disturbed consciousness found to suffer from NCSE; this low percentage was due to the unavailability of EEG, as only 14.4% of the total admitted children (3583) had EEG done at admission. The actual percentage may reach 21.6%, as this is the percentage of children with positive EEG for NCSE in the cohort (112/518), who performed EEG at time of admission. Of the 112 Patients, 46 were males and 66 females; age ranged from 6.2-14 years. Clinically, 57% of the children suffer from complex partial NCSE, 31% from atypical absence NCSE, 7% from typical absence NCSE, and 5% from Simple Partial NCSE (Table 1, Figure 1).
Figure 1: Classification of study
subjects according to dominant type of Non-convulsive Status Epilepticus.
Cryptogenic etiology is the most frequent (47%), followed by presumed perinatal vascular insults (18%) (Table 2, Figures 2-6).
The clinical presentation of NCSE is heterogeneous and the EEG is an essential diagnostic tool [23,24]. In patients with moderate or severe mental retardation, with psychiatric disorders and especially in critically ill patients, a high degree of clinical suspicion is often necessary to establish the diagnosis of NCSE within the shortest possible time. Many reports use the term “NCSE” in an all-encompassing manner, applying this definition for patients with varied clinical manifestations and etiologies, in a way that impairs the distinction between focal and generalized forms, as well as the assessment of prognosis in different situations, thus, taking into consideration data such as etiology, age, clinical and electrographic presentation is of importance, given the fact that the course and prognosis of focal and generalized forms are quite different and possibly dependent on those aspects.
Figure 3: EEG trace of Typical Absence NCSE
Figure 4: EEG trace of Atypical Absence NCSE.
Figure 5: EEG trace of complex partial NCSE
Figure 6: Generalized periodic epileptiform discharge.
Table 1: Classification of study
subjects according to dominant type of Non-convulsive Status Epilepticus.
NCSE Types |
Typical absence NCSE |
Atypical absence NCSE |
Simple Partial NCSE |
Complex Partial NCSE |
Number & % |
8 (7%) |
34 (31%) |
6 (5%) |
64 (57%) |
Table
2: Etiology
of non-convulsive status epilepticus.
NCSE |
Cryptogenic etiology |
Vascular Insult |
Acute symptomatic |
Remote symptomatic |
Acute precipitant |
No.=112 |
52 (47%) |
20 (18%) |
16 (14%) |
14 (12%) |
10 (9%) |
No conflict of interest