This document discusses non-convulsive status epilepticus (NCSE), beginning with definitions and classifications. It then provides several case studies demonstrating EEG findings in NCSE patients and how their status epilepticus responded to treatment with benzodiazepines or other anticonvulsants. The document concludes by outlining treatment recommendations for different types of NCSE, including absence status epilepticus, complex partial status epilepticus, atypical absence status epilepticus, and NCSE occurring in coma.

1. Dr Mohammad A.S Kamil
Consultant neurologist
Neurosciences hospital

3. DEFINITIONS
 A condition of ongoing or intermittent clinical
epileptic activity (without convulsions) for at least 30
minutes with EEG evidence of seizures.
 Non convulsive SE is believed to occur in about 8% of
all comatose patients without evidence of significant
motor signs and persists in 14% of patients following
generalized convulsive status epilepticus.

5. Non convulsive SE is likely under
recognized and under diagnosed.

6. Classification of nonconvulsive
status epilepticus (NCSE)

7. NCSE occurring in the neonatal
and infantile epilepsy syndromes
West syndrome
Ohtahara syndrome
Severe myoclonic encephalopathy of
infancy (SMEI; Dravet syndrome)
NCSE in other forms of neonatal or
infantile epilepsy

8. NCSE occurring only in childhood
NCSE in Early-onset benign childhood occipital epilepsy
(Panayiotopoulos syndrome)
NCSE in other forms of childhood epileptic
encephalopathies, syndromes and etiologies, e.g., Ring
chromosome X andother karyotype abnormalities,
Angelman syndrome, Rett syndrome, myoclonic-astatic
epilepsy, other childhood myoclonic encephalopathies
Electrical status epilepticus in slow wave sleep (ESES)
Landau-Kleffner syndrome

9. NCSE occurring in both childhood
and adult life
With epileptic
encephalopathy
NCSE in the Lennox-Gastaut
syndrome
i. Atypical absence status
epilepticus
ii. Tonic–status epilepticus
Other forms of NCSE in
patients with learning disability
or disturbed cerebral
development (cryptogenic or
symptomatic)
Without epileptic
encephalopathy
Typical absence status epilepticus in
idiopathic generalized epilepsy
Complex partial status epilepticus:
i. Limbic ii. Nonlimbic
NCSE in the postictal phase of tonic–
clonic seizures
Subtle Status epilepticus (myoclonic SE
occurring in the late stage of convulsive
SE)
Aura continua (with: i. sensory, ii. special
sensory, iii. autonomic, iv. cognitive
symptoms)

10. NCSE occurring in late adult life
De novo absence status epilepticus of late onset

11. Boundary syndromes : cases in which it is not clear to what
extent the continuous epileptiform electrographic abnormalities are contributing to the clinical
impairment.
Some cases of epileptic encephalopathy.
Some cases of coma due to acute brain
injury with epileptiform EEG changes.
Some cases of epileptic behavioral
disturbance or psychosis.
Some cases of drug induced or metabolic
confusional state with epileptiform EEG
changes.

12.  47 year-old man with generalized tonic-clonic seizures and
absences since age 17. Valproic acid (VPA) and primidone never
completely controlled his seizures. He developed severe
hyperammonemic encephalopathy and had to be switched to
levetiracetam (LEV), lamotrigine (LTG), and topiramate. He then
experienced several episodes of AS where he was walking around,
but was confused. He could speak and responded to questions,
but mimicked Ganser’s syndromes in that his most answers were
“near- correct” (October 17 instead of November 17, for example).
The EEG showed almost permanent primary generalized (poly-
)spike-wave discharges with short bouts of normal background
activity (A). Absence status did not stop after i/v-administration
of 8 mg of lorazepam (LZP), but the background activity became
flattened and beta activity was increased (B). The subsequent i/v-
administration of 1 mg of midazolam (MDL)(C) completely
abolished the epileptic activity within 90sec.(D).

14.  84 year-old otherwise healthy woman who was found
slightly confused in her apartment. A CT scan and the CSF
were completely normal. Within 24 hours, she became
comatose. The EEG showed diffuse, irregular, sharp-
contured, high-amplitude theta- and delta activity,
intermingled with multifocal sharp waves (A). This activity
did not change upon eye opening (B). The i/v-
administration of 0.5 mg MDL (C) markedly reduced the
epileptic activity and led to an accelerated, more regular
background activity within 90 seconds (D). The patient
opened her eyes and briefly talked. Extensive work-up did
not reveal another cause than BZD intake for insomnia and
an involuntary stop of this medication a few days before
admission because of medication run-out.

16.  53 year-old woman with acute respiratory
exhaustion after left ventricular decompensation
and subsequent pulseless electric activity.
Successful outdoor reanimation after an
estimated time of hypoxia of 35 minutes. She was
treated by hypothermia for 24 h. EEG after
rewarming without sedative drugs showed a
spontaneous burst-suppression pattern with
spikeslow-and sharp-slow-waves with clinical
myocloni. She remained deeply comatose and
somatosensory evoked potentials 48h later
showed absence of cortical responses.

18.  81 year-old patient with sepsis caused by E. coli,
prosthetic hip infection and multiple retroperitoneal
abscesses wastreated with rifampicine and cefepime;
two days later, acute renal failure occurred and the
patient was comatose despite immediatedialysis.
 The EEG (A) showed periodic triphasic waves (TPW)
(*left box) with fronto-occipital shift (**); additionally,
multifocal epileptic discharges (***, boxes in the
middle and at the right) were observed in both
paracentral regions and over the right temporal
region. Intravenous administration of 1 mg of LZP (B)
led to complete abolition of both the TPW and the
epileptic discharges.

20.  (A) Normal electroencephalogram from a 6-month-
old child. (B) Absence status epilepticus in a 6-year-
old child who presented with unresponsiveness with
subtle twitching of the corner of the mouth. The
electroencephalogram shows continuous rhythmic
generalized spike-and-wave discharges with frontal
predominance.

23. Treatment of absence SE
 There is no evidence that absence status induces neuronal damage, and thus
aggressive treatment is not warranted.
 Treatment can either be intravenous or oral.
 Absence status epilepticus is often precipitated by the prescription of
inappropriate antiepileptic drugs in idiopathic generalised epilepsy (e.g.
carbamazepine).
 Absence status epilepticus responds rapidly to intravenous benzodiazepines,
and these are so effective that the response is diagnostic.
 Lorazepam at 0.05-0.1 mg/kg is the benzodiazepine of choice.
 The effect may only be transient and a longer acting AED may need to be given.
 If intravenous treatment is required, but either benzodiazepines are ineffective
or contraindicated then intravenous valproate (20-40 mg/kg) can be given. In
cases of primary generalised epilepsy treatment should be continued with a
suitable AED.
 If a precipitating factor can be identified in lateonset de novo cases, then
longterm therapy is not usually indicated.

24. Complex partial status epilepticus
 How aggressively complex partial status epilepticus needs to be
treated depends upon: the prognosis of the condition; and if
treatment improves the prognosis.
 As in all epilepsies the prognosis relates partly to the prognosis
of the underlying aetiology and any concomitant medical
conditions.
 At present, early recognition of the condition and treatment with
oral or rectal benzodiazepines is recommended; oral clobazam
has proven to be an effective treatment .
In patients who have repetitive attacks of complex partial status
epilepticus, oral clobazam (10-20 mg/day) over a period of 2-3
days given early at home can usually abort the status epilepticus,
and such strategies should be discussed with patient and carers.

25. Atypical absence status epilepticus
 This condition is usually poorly responsive to
intravenous benzodiazepines, which should, in any
case, be given cautiously, as they can induce tonic
status epilepticus in these patients.
 Oral rather than intravenous treatment is usually more
appropriate, and the drugs of choice are valproate,
lamotrigine, topiramate, clonazepam and clobazam.
 Sedating medication, carbamazepine and
vigabatrin have been reported to worsen atypical
absences.

26. Nonconvulsive
status epilepticus in coma
 Electrographic status epilepticus in coma is not uncommon and is seen
in up to 8% of patients in coma with no clinical evidence of seizure
activity.
 The diagnosis is often debatable as in many instances burst
suppression patterns, periodic discharges and encephalopathic
triphasic patterns have been proposed to represent electrographic
status epilepticus, while these mostly indicate underlying widespread
cortical damage or dysfunction.
 This condition should be treated aggressively with deep anaesthesia
and concomitant AEDs.
 The association of electrographic status epilepticus with subtle motor
activity often follows hypoxic brain activity and has a poor prognosis,
but aggressive therapy with benzodiazepines, phenytoin and increased
anaesthesia is perhaps justified, since the little evidence available
indicates that such treatment improves prognosis.