‘Ictal epileptic headache’: Recent concepts for new classifications criteria

Dear Sir,

More frequently associated than expected on the basis of coincidence, headache and epilepsy are both characterized by transient paroxysmal episodes of altered brain function with clinical, pathophysiological and therapeutic overlap.

Cortical spreading depression (CSD) is probably the connection point between these two conditions. In fact, CSD and an epileptic focus are able to facilitate each other (1–3), and in the central nervous system there is a hierarchical organization based on ‘neuronal networks’ (cortical and subcortical) which may be more or less prone to CSD (migraine) and/or an epileptic focal discharge (i.e. seizures). Hyperexcitation occurs in epilepsy, in migraine hypoexcitation followed by hyperexcitation, as rebound phenomenon (spreading depression) (1–3). Moreover, a disexcitability condition (hyper- and hypoexcitation in the same patient at different points in time) has even been demonstrated (1–3).

The International Classification of Headache Disorders (ICHD-2) committee recognizes three nosographic entities concerning the relationship between epilepsy and headache (Table 1). The International League Against Epilepsy (ILAE) classification fully ignores this relationship and headache is described only as a ‘cephalic’ sensation, neither classified as ‘pain’ nor as ‘autonomic’ sensations. Actually, because headache pain originates from terminal nervous fibres (‘vasomotor’) in cerebral blood vessels, headache should be classified as ‘autonomic sensations’ in the ILAE glossary and terminology. In this way, headache could be the sole expression of an epileptic seizure and classified as an autonomic seizure (i.e. ‘ictal epileptic headache’ or IEH).

Table 1.

Current ICHD-2 classification of headache-related seizures and proposed criteria for ictal epileptic headache (IEH).

Current ICHD-2 classification of headache-related seizures

Migraine-triggered seizure (migralepsy) (1.5.5)

Diagnostic criteria:

A. Migraine fulfilling criteria for 1.2 (‘Migraine with aura’)

B. A seizure fulfilling diagnostic criteria for one type of epileptic attack occurs during or within 1 hour after a migraine aura

Hemicrania epileptica (7.6.1)

Diagnostic criteria:

A. Headache lasting seconds to minutes, with features of migraine fulfilling criteria C and D

B. The patient is having a partial epileptic seizure

C. Headache develops synchronously with the seizure and it is ipsilateral to the ictal discharge

D. Headache resolves immediately after the seizure

Post-ictal headache (7.6.2)

Diagnostic criteria:

A. Headache with features of ‘tension-type headache’ or, in a patient with migraine of ‘migraine headache’ and fulfilling criteria C and D

B. The patient has had a partial or generalized epileptic seizure

C. Headache develops within three hours following the seizure

D. Headache resolves within 72 hours after the seizure

Proposed criteria for ictal epileptic headache (IEH)

Diagnostic criteria A–D must all be fulfilled to make a diagnosis of ‘IEH’

A. Headache* lasting seconds, minutes, hours or days;

B. Headache that is ipsilateral or contralateral to lateralized ictal epileptiform EEG discharges (if EEG discharges are lateralized);

C. Evidence of epileptiform (localized**, lateralized or generalized) discharges on scalp EEG concomitantly with headache; different types of EEG anomalies may be observed (generalized spike-and-wave or polyspike-and-wave, focal or generalized rhythmic activity or focal subcontinuous spikes or theta activity that may be intermingled with sharp waves) with or without photoparoxysmal response (PPRs)

D. Headache resolves immediately after i.v. antiepileptic medication

*

A specific headache pattern is not required (migraine with or without aura, or tension-type headache are all admitted).

**

Any localization (frontal, temporal, parietal, occipital) is admitted.

Since descriptions of IEH in the 1980s (1–3), ictal headache has been reported ‘as a sole epileptic manifestation’ in eleven patients with non-convulsive status epilepticus (1–3). Recently, a retrospective multicentre study described a clinical EEG picture consistent with IEH criteria (Table 1) in 16 of approx. 4600 epileptic children (1).

IEH attack usually lasts longer than ‘seconds to minutes’, it is the sole manifestation of a ‘non-convulsive status epilepticus’ and, in some of them (1) a ‘complete remission’ of the headache as well as of EEG abnormalities was obtained only after anticonvulsant treatment (Table 1). However, these well-documented IEH cases (1) cannot be classified as hemicrania epileptica (Table 1) because they do not meet criteria B ‘is having a partial epileptic seizure’ and D ‘headache resolves immediately after the seizure’. There are also no EEG criteria for hemicranias epileptica.

We therefore propose to add to the forthcoming ICHD-3 classification a new entity, i.e. IEH (2) (Table 1), which defines a condition diagnosed when a headache attack is the only clinical feature of epileptiform discharges. An EEG demonstration of synchronicity of epileptic discharges and headache is required as well as resolution of the headache after administration of an i.v. anticonvulsant drug (1–3). Similarly, we suggest adding IEH, like other types of ‘ictal pain’, to ‘ictal autonomic manifestations’ (1–3) in forthcoming revisions of the ILAE classification.