Presentation and course
Reading epilepsy with jaw myoclonus. Reading-induced seizures usually begin in neurodevelopmentally normal adolescents and consist of clusters of single and brief myoclonic jerks mainly restricted to the masticatory, oral, and perioral muscles (05; 58; 44; 27; 45; 04; 26; 37). The myoclonic form of reading epilepsy may represent a subtype within a larger umbrella of language-induced reflex epilepsy, as related tasks, such as speaking and writing, can induce the same seizure semiology (18).
The most characteristic symptom is an abnormal sensation or movements involving the jaw. This is described as a clicking sensation, jerking, tightness, or numbness and occurs after a variable latency (usually 3 to 20 minutes) from the onset of reading, particularly when reading out loud and when reading difficult or unusual texts. Its severity and frequency varies even in individual patients. One quarter of the patients may have also similar jaw jerks provoked by talking (particularly if this is fast or argumentative; see case 1 of clinical vignettes), writing, reading music, or chewing. Text messages on mobile phones have also been reported as provoking seizures in reading epilepsy (56). There is also an unusual case of a woman whose reading-induced seizures were initiated by specific fonts (57).
As a rule, there is no loss of awareness during the jaw myoclonus. This is expected because the jaw myoclonus is brief and instantaneous without widespread or prolonged cortical involvement. However, many patients complain about a feeling of unrest, discomfort, anxiety, or confusion. Some patients describe themselves as “sticking to the word” or report “loss of track of the reading text” when a jaw jerk occurs and restarting reading from the beginning of the sentence. The phenomenon seems to correlate with the severity of motor manifestations, though some patients may also experience dyslexia or alexia after the jaw myoclonus (01). Ictal stammering may also occur, perhaps because the brief ictal jaw or perioral clonic or tonic activity impedes the flow of speech.
Generalized tonic clonic seizures. The majority have only one generalized tonic clonic seizure (GTCS), which often occurs when the patient continues to read despite jaw jerks or other manifestations. On these occasions, the jaw jerks may become more violent and spread to trunk and limb muscles before a GTCS develops. This is usually the first and last GTCS, as the condition is often effectively treated and the patient learns to stop reading or talking when oral or perioral jerks occur. It is extremely rare for patients with reading epilepsy to have more than one to five generalized tonic clonic seizures while reading and spontaneous. Generalized tonic clonic seizures unrelated to reading are rare as well.
See video EEG in (17).
Other types of reading-induced seizures. It is rare for reading epilepsy to present with other types of ictal manifestations in addition to the jaw myoclonic seizures, although visual hallucinations can occur. Spontaneous myoclonic jerks are rare and may occur in those with a more widespread cortical hyperexcitability than in pure reading-induced epilepsy. Hand myoclonic jerking is common in those with writing precipitation of seizures.
Absence seizures induced by reading are exceptional (32; 51).
An overlap of reading epilepsy with juvenile myoclonic epilepsy was suggested on the basis of clinical findings including the age at onset, bilateral myoclonic jerks, strong influence of heredity, progression to generalized tonic-clonic seizures, response to sodium valproate, and persistence through life (44; 60). The conclusion of Wolf and colleagues is that “perioral reflex myoclonus” is not a specific finding in epilepsy with reading induced seizures, but “it seems to be a reflex epileptic trait which can be observed, like photosensitivity, in conjunction with many epileptic syndromes, both generalized and focal (60). Juvenile myoclonic epilepsy seems to be the syndrome in which it is second most common (with talking as the predominant precipitating mechanism, and reading only in a minority of patients)” (34; 60).
Reading epilepsy with prolonged focal seizures manifested with alexia. In this less common variant of epilepsy with reading induced seizures, the clinical picture is dominated by prolonged (longer than 1 to 3 minutes) focal seizures always triggered by reading and characterized by ictal alexia associated with a posterior temporal ictal discharge in the language-dominant hemisphere (see case 2 of clinical vignettes).
Prolonged alexia is the prevailing ictal manifestation in this form of reading epilepsy, and it is strikingly different from the transitory “loss of track in the text” of the myoclonic variant. Visual symptoms (mainly illusions and palinopsia) are also described by some patients (15).
There are nearly 10 reported cases, but the possibility of under-recognition or misdiagnosis may contribute to its rarity. It is possible that the lack of the typical jaw jerk may have led to the misdiagnosis of some patients as having temporal epilepsy or to the misplacement of others into the group of the poorly defined “secondary” reading epilepsy, which has received little attention in recent years.
The case reported by Chavany and colleagues is usually cited as demonstrating a symptomatic instance of the alexic form of reading epilepsy (08). This was a rather unusual 30-year-old patient with relatively frequent generalized convulsions from the age of 10 months to 8 years. From 8 years of age to the time of the report, the attacks were less severe. The majority of them were evoked by reading. There would be a prolonged warning of various subjective sensations. Seizures began with words and letters changing place vertically and horizontally then becoming entirely incomprehensible. He had an expressive aphasia after some secondarily generalized tonic-clonic seizures. There were structural abnormalities in the left occipital region. The resting EEG was abnormal, and hyperventilation caused small isolated sharp waves in the left occipital region. The ictal EEG was characterized by rhythmical theta activity of left occipital predominance, which was replaced 20 seconds later by delta activity at 1.5 to 2 Hz, with the whole electrical event lasting for approximately 2 minutes.
Gastaut and Tassinari described a 15-year-old boy who, since the age of 6 years, had experienced several epileptic seizures exclusively during prolonged reading (14). On EEG, two seizures were evoked, characterized by the patient seeing the last word in a foggy way; this word became fixed before him even though he kept his eyes closed; then the letters changed place, and the word became distorted. In the first recorded seizure, which occurred while he was doing a Latin translation, the word “invicta” intruded like a true hallucination, then was transformed into “victa” and finally into “victoria” (victory). EEG consisted of a fast rhythmic discharge lasting for 50 seconds, which remained localized at the left parieto-occipital region. A second seizure in the same subject was preceded by a slowing of the reading speed and a laryngeal sensation that coincided with a brief generalized burst of spike-and-wave activity of right predominance. At this moment, the subject interrupted the reading and, a few seconds afterwards said, “I am going to have a seizure.” He was persuaded to continue reading; the laryngeal sensation reappeared, and the reading became irregular. The patient repeated the same words several times; at the same time on the EEG there appeared two sporadic bursts of spikes and waves, predominant in the parietal region of the right hemisphere, followed in that region by the appearance of low-voltage fast activity, intermixed afterwards with spikes and spikes and waves, while the subject presented a deviation of the body and head towards the left followed by a tonic-clonic seizure.
Patient 12 of Radhakrishnan and colleagues was exceptional in that he evidenced both forms of reading epilepsy. He gave a history of inability to comprehend the meaning of the words without any jaw myoclonus before three generalized tonic-clonic seizures induced by reading. This patient had a left posterior temporal-occipital seizure during pentylenetetrazol activation while reading. In addition to the focal seizures, and independent of these, he had reading-induced jaw jerks associated with generalized spike wave discharges (44).
Koutroumanidis and associates described two cases (patients 16 and 17) with video-EEG-documented reading-induced prolonged seizures of alexia (27). Both described an associated dizziness and an ill-defined feeling of discomfort. No other ictal or postictal symptoms or clinical changes were elicited by history or observed on analysis of video tapes. Patient 16 had reading-induced focal seizures that evolved into generalized tonic-clonic seizures on several occasions. In patient 17, reading-induced alexia never evolved into generalized tonic-clonic seizures. He never had spontaneous daytime seizures but suffered infrequent nocturnal convulsions coinciding with the onset of the reading-provoked seizures. The routine EEG was normal in both patients. Reading characteristically provoked a subclinical focal EEG activation over the left posterior temporo-parieto-occipital area. Ictal EEG changes were prolonged and clearly focal over the left posterior temporo-parieto-occipital region. Treatment with phenobarbital, phenytoin, and clonazepam over a period of seven years was ineffective in patient 16; patient 17 received sodium valproate for two years, also without apparent benefit. Introduction of carbamazepine resulted in considerable improvement in both patients, with less frequent reading-induced focal seizures and rare generalized tonic-clonic seizures associated with poor adherence. Brain MRI was normal in patient 17. An arachnoid cyst at the left temporal pole was found in patient 16.
Maillard and associates described two cases of video-EEG-documented reading-induced focal seizures manifesting with alexia. Onset was in adolescence. There were no spontaneous seizures and no other triggers other than reading. Brain MRI was normal (30). Case 1 was a right-handed 41-year-old man who had his first seizures at the age of 14 years. Seizures were provoked by reading both silently and aloud and began with a feeling of dizziness and inability to continue reading, followed by a sensation of oropharyngeal discomfort. Attempts to continue reading provoked generalized tonic-clonic seizures. The duration of reading necessary to elicit a seizure was variable, either brief (such as reading a road sign when stressed) or extended up to 10 minutes. In one of his EEG-recorded seizures provoked by reading.
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The patient warned of seizure onset by raising his right hand. Speech arrest, facial flushing, and jaw clenching were observed. No hemianopia was found on postictal examination. The patient reported an initial indefinable sensation of dizziness, difficulty reading, and jaw discomfort. He confirmed that he had stopped reading voluntarily, fearing a generalized tonic-clonic seizure, when he no longer understood the words and tried to read letter by letter. EEG showed a discharge recorded from the left posterior temporal and basal electrodes (30). |
Case 2 was a 40-year-old right-handed male patient who had his first seizures at the age of 14 years while reading a German text in school. Seizures began with alexia followed by loss of contact and chewing and occurred after several minutes of silent reading. He never had any spontaneous seizures. Generalized tonic-clonic seizures occurred once or twice a year:
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Four seizures recorded on video-EEG were provoked by silent reading of French or German text. The duration of reading ranged from 13 to 19 minutes until seizures appeared. Interictal EEG was normal. Reading elicited left temporo-occipital spikes. The three recorded seizures were similar, beginning with a sigh, followed by impaired contact, chewing movements, salivation, and sweating. Postictal examination revealed anomia without loss of comprehension or hemianopia. When questioned, the patient reported an inability to read accompanied by hot flushes and confirmed that he had wanted to read letter-by-letter. The EEG during these three seizures was characterized by a left temporo-occipital discharge lasting about 50 seconds. The other recorded seizure, provoked by reading a French text, showed a relatively high-amplitude (about 100 µV) right temporal delta discharge (3 to 4 Hz) lasting about 40 seconds. He continued reading with chewing automatisms and did not report any subjective sensation. After several treatments with various antiepileptic drugs, topiramate has allowed precarious control (30). |
Osei-Lah and colleagues described a 19-year-old right-handed student with reading-induced focal seizures of alexia progressing to generalized tonic-clonic seizures (40). “While reading very late at night his reading suddenly became disturbed; he could not make sense of what he was reading and felt confused. He then lost awareness and recovered in the ambulance en route to a hospital.” He never had jaw or facial myoclonic jerks associated with his seizures. All of his seizures were associated with reading at the onset. He reported that the seizures were more likely to occur when reading difficult material or printed material with small font and when reading during late afternoon or evening or when he was tired. He frequently read at other times without any problems. Writing, talking, solving mathematical problems, or listening to material being read to him did not trigger a seizure. He had not attempted reading texts in foreign languages. Brain MRI was normal. The interictal EEG was practically normal. Reading (both silently and aloud) consistently evoked sharp and slow wave complexes over the left mid- and posterior temporal regions, which ceased when the patient stopped reading. He reported no symptoms during these. Prolonged reading resulted in a 6-minute focal seizure of left posterior temporal onset with secondarily generalization. The patient reported difficulty making sense of the text at the onset of the seizure. No facial, jaw, or limb myoclonic jerks were seen.
Gavaret and colleagues studied a 31-year-old right-handed woman with focal seizures that always occurred during silent reading (15). Seizures began at the age of 28 years. During the three years prior to assessment, she had experienced a total of eight seizures. Physical and neurologic examinations were normal. Seizures began during silent reading with the feeling of no longer being able to understand what she was reading. After looking up from the page, she then continued to see letters and words despite actual disappearance of that image from either visual field (palinopsia). She had a feeling of strangeness. She could then have right hemi-body jerks and secondarily generalization. Seizures usually occurred soon after the onset of reading (less than 10 minutes). She had not abandoned reading altogether but had developed a distinct style of reading to try to avoid the onset of seizures, in that she read only for short periods and tended to scan the page diagonally. She was initially treated by lamotrigine (200 mg/day), but seizures persisted with secondarily generalization. Replacement of lamotrigine with carbamazepine (1000 mg/day) led to a considerable improvement. Brain MRI was normal. Interictal EEG showed isolated left posterior temporal spikes. Interictal [18 F] fluorodeoxyglucose-PET showed bilateral occipito-temporal hypometabolism with left-sided predominance. During video-EEG monitoring, a seizure was recorded five minutes after silent reading of a women’s magazine. Clinically, the patient experienced habitual subjective signs (alexia, dyslexia, palinopsia). She stopped reading at the beginning of the seizure and signaled to the nurses. She was able to explain that a seizure had started. Then, she had right-sided convulsive movements progressing to a generalized tonic-clonic seizure. Ictal EEG showed a rhythmic discharge localizing to the left temporo-parieto-occipital junction. Interictal high-resolution EEG highlighted the left occipito-temporal junction. Interictal PET demonstrated bilateral occipito-temporal hypometabolism with left-sided predominance. MRI fusion of the coregistered subtraction between ictal and interictal SPECT showed relative hyperperfusion affecting (1) the left occipito-parietal junction area, (2) the left lateral middle and inferior temporal gyri, and (3) the left inferior frontal area.
A small number of reported cases do not fit the typical descriptions of either the myoclonic or the focal variant of reading epilepsy (06; 52; 10).
Prognosis and complications
The seizures in epilepsy with reading-induced seizures are usually mild, and there is no deterioration in neurologic status or in seizure control over time. Furthermore, the response to medication is usually excellent, and seizures may also improve with modification of the triggering factors. However, epilepsy with reading-induced seizures is probably enduring (though some improvement may occur after the age of 40 to 50 years), and reading-induced seizures may be a significant source of disability in those with continuing seizures in whom reading is an essential part of their life and profession.
Clinical vignette
Case 1: Reading epilepsy with jaw myoclonus. A 34-year-old woman with reading epilepsy manifesting with jaw myoclonus started at 15 years of age. Jaw myoclonus was consistently provoked by reading. Only once had a generalized tonic-clonic seizure occurred when she continued reading despite increasing jaw myoclonic jerks because she wanted to see what would happen. She did not have any other spontaneous or reflex seizures. The diagnosis of epilepsy with reading-induced seizures was made at 26 years of age, and this was confirmed with EEG.
No additional seizures occurred in the next eight years after treatment with clonazepam 0.5 mg nightly was initiated. Previous treatment with phenytoin was entirely ineffective. Her older sister also had similar symptoms of jaw myoclonus when speaking rapidly. She never asked medical advice for her condition and never had any other type of seizures. She gave the following written account of her symptoms: “I had jaw jerking but I can’t remember having one recently. It used to happen quite frequently when I was about 14, at school, and always when I was talking. I was talking quite rapidly at the time, and it was like a very quick uncontrollable spasm. It didn’t last long enough for anyone else to notice, but my flow of speech was disrupted.”
Case 2: Reading epilepsy with focal seizures of alexia. A 29-year-old right-handed man was referred at the age of 24 years with a 2-year history of infrequent nocturnal convulsive seizures for which he was treated with sodium valproate, without apparent therapeutic effect. He had also experienced episodes of alexia since the age of 22 years. These usually occurred after prolonged reading and invariably consisted of gradual loss of ability to recognize, first, the infrequently encountered letters, then the commonest ones like the letter “A,” and finally the numbers. These episodes would last for 1 to 2 minutes, after which the ability to understand reading material would resume in the reverse order. During the seizure, he could understand other people talking to him, but he was limited in his ability to respond. He described an associated slight dizziness and a feeling of discomfort, but he never experienced these symptoms or other symptoms suggesting epileptic seizure activity when he was not reading. Episodes of paroxysmal alexia occurred almost daily and were worse when he was tired. Reading figures, talking, writing, playing cards or chess or solving mathematical problems did not provoke any symptoms. The patient had prolonged video-EEG studies during the alert resting state, multiple reading sessions, and all-night natural sleep. The EEG during the resting state, hyperventilation, and photic stimulation was normal. Reading consistently activated the EEG, resulting in frequent asymptomatic brief small spike-and-wave discharges over the left temporoparietal area, alternating with runs of low voltage regular slow activity at 3 to 4 Hz, lasting up to 4 seconds. One of the patient’s habitual seizures was recorded on video-EEG and lasted for 75 seconds. During the subsequent all-night natural sleep, spike-and-wave discharges were apparent over the left temporal area. Replacement of sodium valproate with carbamazepine 600 mg/day led to a considerable improvement, with only occasional episodes of reading-induced alexia over a follow-up period of five years. A single nocturnal generalized tonic-clonic seizure occurred in the setting of poor adherence. Follow-up video-EEGs showed only occasional bursts of left-sided slow waves evoked by reading. Talking, writing, and solving mathematical problems never exerted any influence on the EEG, and generalized discharges were never recorded.