Presentation and course
Reading epilepsy with jaw myoclonus. This is the most common form of epilepsy with reading-induced seizures, accounting for more than two thirds of cases (38). Onset is typically in the late teens. Seizures consist of clusters of single and brief myoclonic jerks mainly restricted to the masticatory, oral, and perioral muscles (05; 52; 39; 22; 40; 04; 21; 32). 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 (14).
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, unusual, and semantically loaded texts (25). The severity and frequency of events vary even in individual patients. Approximately 25% of patients may also experience similar jaw jerks provoked by other activities such as 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 (50). There is also an unusual case of a woman whose reading-induced seizures were initiated by specific fonts (51).
Awareness is typically preserved during jaw myoclonus, which is expected given its brief, instantaneous nature and limited cortical involvement. However, patients commonly report associated symptoms including feelings of unrest, discomfort, anxiety, or confusion. Many describe "sticking to the word" or losing track of the text when jaw jerks occur, requiring them to restart reading from the beginning of the sentence. The severity of these cognitive disruptions appears to correlate with the intensity of motor manifestations. Some patients may experience transient dyslexia or alexia following the jaw myoclonus (01). Ictal stammering can also occur, likely due to the interference of brief jaw or perioral motor activity with normal speech production.
Generalized tonic-clonic seizures. Over 80% of patients with reading epilepsy experience at least one bilateral tonic-clonic seizure during their course (38). These typically occur when the patient continues to read despite jaw jerks or other warnings. On these occasions, the jaw movements often become more severe and spread to the trunk and limb muscles before evolving into a bilateral tonic-clonic seizure. Most patients only experience one or very few bilateral tonic-clonic seizures, as the condition is often effectively treated, and patients learn to stop reading when warning signs occur. Spontaneous bilateral tonic-clonic seizures unrelated to reading are uncommon in this population.
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 symptoms can occur, described as blurred vision, palinopsia, and moving text (38). 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 (28; 46).
Co-occurrence of juvenile myoclonic epilepsy and reading epilepsy has been reported (39; 54). Wolf and Inoue concluded that perioral reflex myoclonus is not specific to epilepsy with reading-induced seizures, but rather that it is a trait of reflex epilepsy that can be observed, like photosensitivity, in isolation and in conjunction with multiple syndromes (54).
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 (12).
There are fewer than 15 reported cases, but the possibility of under-recognition or misdiagnosis may contribute to its rarity. The lack of the typical jaw jerk may lead 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 (07). 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. Most 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 and 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 (11). Two seizures were recorded, characterized by the patient seeing the last word in a foggy way. This word became fixed before him, even when he closed his eyes; the letters then 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). The EEG showed a fast rhythmic discharge lasting for 50 seconds, which remained localized at the left parieto-occipital region. A second seizure 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 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, the EEG showed two sporadic bursts of spikes and waves maximal in the right parietal region, followed by the appearance of low-voltage fast activity in the same region, which progressed to spikes and then spikes and waves. There was deviation of the body and head toward 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 (39).
Koutroumanidis and associates described two cases (patients 16 and 17) with video-EEG-documented reading-induced prolonged seizures associated with alexia (22). 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 during video analysis. Patient 16 had reading-induced focal seizures that evolved into generalized tonic-clonic seizures on several occasions. Patient 17 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 in the setting of 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 (26). 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, the patient warned of seizure onset by raising his right hand, followed by speech arrest, facial flushing, and jaw clenching. The patient recalled an indefinable sensation, difficulty reading, and jaw discomfort. He confirmed that he had stopped reading voluntarily--when he no longer understood the words and tried to read letter by letter, fearing an impending seizure. EEG showed a discharge recorded from the left posterior temporal and basal electrodes (26).
Case 2 was a 40-year-old right-handed male patient who had his first seizures at the age of 14 years while reading in school. His seizures began with alexia, followed by loss of awareness and chewing movements. He did not have spontaneous seizures. Bilateral tonic-clonic seizures occurred once or twice per year. During video-EEG monitoring, four seizures were recorded during silent reading of French and German texts, with seizure onset occurring 13 to 19 minutes after beginning to read. The interictal EEG was normal. Reading elicited left temporo-occipital spikes. Three of the seizures, triggered by German texts, began with a sigh and progressed to impaired awareness, chewing movements, salivation, and sweating. Post-ictally, he demonstrated anomia with retained comprehension. There were no visual field deficits. The patient reported feeling hot and being unable to read except letter-by-letter during these episodes. These seizures showed left temporo-occipital discharges lasting approximately 50 seconds on EEG. The fourth seizure, triggered by French text, showed a different pattern--a high-amplitude (100 µV) right temporal 3 to 4 Hz delta discharge lasting 40 seconds, during which he continued reading with chewing automatisms but reported no symptoms. After trials of various antiseizure medications, he achieved modest seizure control with topiramate (26).
Osei-Lah and colleagues described a 19-year-old right-handed student with reading-induced focal seizures characterized by alexia progressing to bilateral tonic-clonic seizures (34). He recalled that at seizure onset, he could not make sense of what he was reading and felt confused, and then lost awareness. He reported that the seizures were more likely to occur when reading difficult material or printed material with a 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 seizures. He did not suffer from unprovoked seizures. He never had jaw or facial myoclonic jerks. Brain MRI was normal. The interictal EEG was essentially normal. Reading silently and aloud both evoked sharp and slow wave complexes over the left mid- and posterior temporal regions that ceased when the patient stopped reading. He reported no symptoms during these. Prolonged reading resulted in a 6-minute left posterior focal seizure that progressed to a bilateral tonic-clonic seizure.
Gavaret and colleagues studied a 31-year-old right-handed woman with focal seizures that occurred during silent reading (12). Seizures began at the age of 28 years. She had experienced a total of eight seizures in the 3 years before assessment. Seizures began with the feeling of no longer being able to understand what she was reading. After looking up from the page, she continued to see letters and words despite the disappearance of that image from either visual field (palinopsia). She had a feeling of strangeness. Some of her seizures progressed to right hemibody jerks and then bilateral tonic-clonic seizures. Seizures usually occurred within 10 minutes of the onset of reading. She had not abandoned reading altogether but had developed a distinct style of reading to try to avoid the onset of seizures, where she read for short periods and tended to scan the page diagonally. Interictal EEG showed isolated left posterior temporal spikes. During video-EEG monitoring, a seizure was recorded 5 minutes after silent reading of a women’s magazine. The patient recalled her habitual subjective signs (alexia, dyslexia, palinopsia). She stopped reading at the beginning of the seizure, signaled to the nurses, and explained that a seizure had started. She then had right-sided convulsive movements progressing to a bilateral tonic-clonic seizure. Ictal EEG showed a rhythmic discharge localizing to the left temporo-parieto-occipital junction. Interictal high-resolution EEG highlighted a spike focus involving the left occipito-temporal junction. Physical and neurologic examinations were normal. Brain MRI was normal. 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 involving the left occipito-parietal junction area, the left lateral middle and inferior temporal gyri, and the left inferior frontal area. She was initially treated with lamotrigine, with persistent bilateral tonic-clonic seizures. These improved considerably with a transition to carbamazepine (1000 mg/day).
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. Seizure freedom is expected in approximately 50% of cases, 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 starting at age 15 years. Jaw myoclonus was consistently provoked by reading. She had one generalized tonic-clonic seizure 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 8 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 gave the following 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.” She never sought medical advice for her condition and never had any other type of seizures.
Case 2: Reading epilepsy with focal seizures of alexia. A 29-year-old right-handed man was initially 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 a 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, including multiple reading sessions. 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 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.
