The variants of reading epilepsy. A clinical and video-EEG study of 17 patients with reading-induced seizures

Abstract

We present the clinical and electrographic data of 17 patients with reading-induced seizures documented with ictal video-EEG studies during provocation with language related tasks. The median age at onset was 15 years (range 11-22 years) and the male:female ratio was 2.4. Fourteen patients had no spontaneous seizures of any type while the remaining three had infrequent generalized tonic-clonic seizures during nocturnal sleep. Two distinct electroclinical ictal patterns were confirmed on video-EEG analysis. (i) Fifteen patients had reading-induced jerks which invariably involved the region of the jaw but also included the upper limbs in five of them. Ictal EEG discharges were noted in 12 patients; these were brief but varied in terms of morphology and spatial distribution, with a clear tendency for left-sided predominance. All but one of these patients had similar myoclonic seizures induced by linguistic activities other than reading, the phenomenon probably justifying the term 'language-induced epilepsy'. Some patients had evidence of transient cognitive impairment associated with the reading-induced jaw or limb jerks. Three patients had a sibling with reading epilepsy but there was no other family history of epileptic seizures. (ii) Two patients had reading-provoked paroxysmal alexia without motor symptoms, associated with prolonged focal ictal EEG abnormalities. Reading provoked a subclinical, continuous and reproducible EEG activation over the left posterior temporal area. We propose that ictogenesis in reading or language-induced epilepsy is based on the reflex activation of a hyperexcitable network that subserves the function of speech and extends over multiple cerebral areas on both hemispheres. The parts of this network responding to the stimulus may, secondarily, drive the relative motor areas producing the typical regional myoclonus. This network hyperexcitability can be genetically determined and its clinical expression is age-related.

Supplementary motor cortex involvement in reading epilepsy revealed by magnetic source imaging

“…This MSI investigation suggests that RE-PMJs are associated with reading-induced activation of hyperexcitable neurons in the left SMC, followed by secondary propagation to the left PSMFA producing the myoclonus. KEY WORDS: Reading epilepsy, Reflex epilepsy, Magnetoencephalography, Magnetic source imaging, Supplementary motor cortex.Reading epilepsy (RE) is a rare idiopathic partial reflex epileptic syndrome characterized by two types of readinginduced seizures (Koutroumanidis et al, 1998;Gavaret et al, 2010;Koepp 2010;Maillard et al, 2010;Miller et al, 2010). The most common seizure type associates perioral myoclonic jerks (PMJs) with left-dominant frontotemporal spike-wave discharges (SWDs).…”

“Txt”-induced seizures indicating reading epilepsy in the mobile phone age

“…1 As well as printed text, computer screens and television have been implicated. [2][3][4][5] The duration and complexity of the reading task may influence the likelihood of reflex seizures. 6 Induced seizures are typically myoclonic, often involving orofacial or jaw myoclonus, but may be partial, manifesting with visual symptoms and alexia.…”

“…The localisation of seizures may vary within an individual patient. 2,4,8 Functional imaging studies have shown activation of the reading and speech-language network bilaterally. 7,9,10 Reading-induced seizures are often initially not recognised, and can be mistaken for non-epileptic events, 3,5,11 with a not infrequent delay to diagnosis.…”

“…4 Although some choose to avoid seizures through limiting reading, anti-epileptic drugs can enable normal function in a text-rich world. 2,7 Computer use-induced seizures have been reported. Smaller hand-held digital devices such as mobile phones are now ubiquitous in most of the world.…”

Did Herbert Spencer Have Reading Epilepsy?

“…While the original description of the syndrome in the 1956 American report has been largely validated, the proposed differentiation between primary versus secondary reading epilepsy has become blurred: In some otherwise typical "primary" cases, fits may be triggered by activities other than reading and the EEG findings are sometimes focal rather than generalized (e.g., Koutroumanidis et al, 1998). The discovery that other linguistic modalities, for example, writing and speaking, can precipitate seizures, with the consequent demarcation of the "language-induced" epilepsies (Geschwind & Sherwin, 1967), has broadened the conceptual frame for reading epilepsy.…”