Migralepsy and migraine in the puerperal period

Dear Editor:

We present the case of a 34-year old woman with a history of right frontal pulsatile headache between the ages 11 and 20; episodes were preceded by a right faciobrachial tingling sensation and the appearance of a bright zigzag pattern at the centre of the visual field, extending to the periphery for more than 5 minutes. This left a right homonymous scotoma, white or black in colour, which lasted 20 minutes, scoring the maximum of 10 on the Visual Aura Rating Scale (VARS; scores are distributed as follows: 3 points for duration of aura 5-60 min, 2 points for progression of aura ≥5 min, 2 points for presence of scotoma, 2 points for zigzag lines, and 1 point for homonymous distribution of visual symptoms). A score of 5 on the scale is diagnostic of aura with a sensitivity of 91% and a specificity of 96%.¹

Eight days after a normal delivery, she experienced a persistent left frontal pulsatile headache for 2 days; she developed right homonymous hemianopia with the described characteristics. She subsequently presented complete vision loss in the form of white scotoma with photopsias; headache was holocranial and intense at that time. The neurological examination conducted at the emergency department revealed bilateral amaurosis with an intact pupillary light reflex. During the examination, the patient presented a generalised tonic-clonic seizure with no other previous manifestations; this lasted 2 minutes and resolved with intravenous diazepam.

The patient was confused following the seizure; she experienced no further seizures after starting treatment with sodium valproate. Headache remitted 6 hours after administration of metamizole and dexketoprofen; amaurosis resolved after 48 hours (VARS, 2 + 2 + 2 = 6). The patient subsequently experienced episodes of hemicranial headache without aura or epileptic seizures.

Brain MRI, cerebral pan-angiography, blood tests (including antinuclear antibodies and anti-β2 glycoprotein I levels), and urine and cerebrospinal fluid (CSF) analyses yielded normal results; 2 electroencephalographies (EEG) revealed normal bioelectrical activity, with no epileptiform discharges.

During the postpartum period, the following diagnoses should be considered when an episode of headache with vision loss is accompanied by an epileptic seizure: (1) thrombosis of cerebral veins or arteries and reversible cerebral vasoconstriction syndrome, which may be ruled out by brain angiography; (2) posterior reversible encephalopathy syndrome, which may be ruled out by normal MRI results; (3) postpartum preeclampsia,² which may be ruled out by absence of arterial hypertension and proteinuria; (4) occipital-onset epilepsy with secondary generalisation, which may be ruled out by a normal EEG reading and visual aura not suggesting seizures; (5) meningoencephalitis, which may be ruled out by normal CSF and neuroimaging findings; and (6) migralepsy.

Our patient met the diagnostic criteria for migraine with aura according to the third edition of the International Classification of Headache Disorders, (ICHD-3 beta). An epileptic seizure occurring during migraine aura, or in the hour following the aura, is referred to as migralepsy (epileptic seizure triggered by migraine, according to ICHD-3 beta). Diagnosis requires: (1) presence of an epileptic seizure meeting diagnostic criteria for any type of seizure; (2) presence during migraine aura, or in the hour following aura, and (3) seizure not being attributable to other disorder.^3,4 Our case matches this definition, as the seizure took place during the migraine aura.

Although these diagnostic criteria are clear, cases have been described of migralepsy preceded by migraine without aura,⁵ its diagnosis in some published cases has been questioned,⁶ and the existence of migralepsy as an entity remains a topic of debate.⁴

In migralepsy, migraine aura should be differentiated from epileptic visual hallucinations, which mainly consist of coloured, unstable circular images which consistently follow the same onset and progression patterns, lasting a few seconds and progressing faster than migraine.⁷

The patient displays some unusual clinical manifestations: (1) recurrence of migraine during the postpartum period after 14 years without headache; (2) initial absence of migraine aura and a different location than that of headache; (3) non-habitual aura, consisting in right homonymous hemianopia followed by bilateral amaurosis with photopsias, suggestive of basilar migraine,^3,8 and described in a case of migralepsy⁶; the duration of amaurosis was also surprising, exceeding that of headache. However, variability of aura characteristics and duration and headache location is a proven fact in migraine.⁹

The mechanism associating migraine and epilepsy remains unknown.⁵ It has been suggested that the occipital cortex has a low excitation threshold during migraine aura; probably, as a consequence of this, the cortical spreading depression wave may facilitate the occurrence of epileptic seizures.^5,6,10 In support of this hypothesis, mutations of SCN1A (which codes for the Na_v1.1 ion channel) have been reported to cause both migraine and epilepsy.¹¹

Ovarian hormones affect the excitability of the cerebral cortex (oestrogens increase excitability and progesterone decreases it).¹² Fluctuations in plasma levels of these hormones condition the occurrence of migraine and epilepsy,¹³ since migraine is more frequent in the catamenial period and less frequent during pregnancy and menopause.^9,14,15 Ours is the first case of migralepsy during the postpartum period and such a prolonged duration of visual aura.

This case illustrates the variability of migraine manifestations during the postpartum period, since aura may be different than normal, with longer duration, and migraine may manifest without aura^4,5,8 or cause a first episode of migralepsy.