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Keywords:

  • Juvenile myoclonic epilepsy;
  • Semiology;
  • EEG;
  • Focal features

Abstract

  1. Top of page
  2. Abstract
  3. PATIENTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Summary: Purpose: A few reports have described focal electroencephalographic or clinical features or both of juvenile myoclonic epilepsy (JME), but without video-EEG documentation. We examined focal clinical and EEG features in patients with JME who underwent video-EEG monitoring.

Methods: Twenty-six patients (nine males and 17 females) who had seizures recorded during video-EEG monitoring were included. Age at seizure onset was 0 to 22 years (mean, 12.3 years), and age at monitoring was 12 to 44 years (mean, 26.5 years). In one patient with left parietooccipital epilepsy, primary generalized tonic–clonic seizures developed after resection of the parietal tumor. Two patients had both temporal lobe epilepsy and JME. Videotaped seizures in each patient were analyzed. Interictal and ictal EEG also were analyzed for any focal features.

Results: Focal semiologic features were observed in 12 (46%) of 26 patients. Six patients had focal myoclonic seizures, and two had Figure 4 sign: one with version to the left, and another had left version followed by Figure 4 sign, and left arm clonic seizure. Their ictal EEGs were generalized at onset but with a lateralized evolution over the right hemisphere. The patient who had both JME and left parietooccipital epilepsy, right arm clonic seizure, and Figure 4 sign was seen during a generalized EEG seizure. Interictally, one patient had temporal sharp waves, and another had run of spikes in the right frontal region.

Conclusions: Fourteen (54%) of 26 patients with JME exhibited focal semiologic or electroencephalographic features or both. Video-EEG was essential in reaching a correct diagnosis and choosing an appropriate antiepileptic drug regimen.

Juvenile myoclonic epilepsy (JME) is an idiopathic generalized epilepsy (IGE) that typically presents with generalized tonic–clonic, myoclonic, or absence seizures, or a combination of these. In typical cases of JME, the seizures are usually bilateral and symmetric, and EEG shows generalized interictal epileptiform discharges and a generalized seizure pattern that also is bilaterally synchronous (1).

However, a few reports concern clinical or EEG focality or asymmetry or both in patients with JME (2–5). Asymmetry of myoclonic jerks may lead to a misdiagnosis of focal epilepsy, resulting in inappropriate or ineffective treatment with medications such as carbamazepine leading to continued seizures and/or side effects. These previous studies did not employ video-EEG monitoring to evaluate these atypical cases of JME. We describe our experience with 26 such patients in whom the diagnosis of JME could be established only with the help of video-EEG monitoring.

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. PATIENTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Between 1990 and 2002, 157 patients were diagnosed as JME at our outpatient clinic. Thirty-three of them were diagnosed based on the results of video-EEG monitoring. Clinical seizures were recorded in 28 patients. No seizures were recorded in five patients. Two of 28 patients were excluded because their video-EEGs were unavailable for review. In total, 26 patients were included in this study.

The clinical characteristics of the patients are shown in Table 1; nine male and 17 female patients are included. Age at seizure onset was 0 to 22 years (mean, 12.3 years), and age at video-EEG monitoring was 12 to 44 years (mean, 26.5 years). Duration of monitoring was 2 to 8 days (mean, 4.9 days). Three patients (patients 24, 25, and 26) had both focal epilepsy and JME. Patient 24, whose seizure was characterized by aura and automatism, had seizure onset at the age of 0 year, and video-EEG monitoring proved that he had left temporal lobe epilepsy and JME. Patient 25 had a history of a right temporal lobectomy for right temporal lobe epilepsy at age 18 years. After surgery, she began having seizures characterized as generalized convulsions with no aura and a second type of seizure characterized as muscle jerks involving the upper extremities. Patient 26 had both left parietooccipital lobe epilepsy and JME. She had primary generalized tonic–clonic (GTC) seizures after resection of the left parietal tumor; her father has typical JME. Family history of epilepsy was present in eight patients. Most patients were admitted for diagnostic evaluation. Seizures in at least eight patients, including two patients who had both focal epilepsy and JME, were medically intractable. Two of them had vagus nerve stimulators for intractable seizures. Seven patients were initially misdiagnosed as having focal epilepsy. One of them was suspected of having temporal lobe epilepsy. Four of them complained of subjective symptoms such as tunnel vision or numbness before seizures, and these symptoms were initially interpreted as auras at outpatient clinic. Two of them were witnessed to have head turning. Three of them were considered to have unilateral jerks. Only four of 26 patients were suspected of having JME before video-EEG monitoring. Magnetic resonance imaging (MRI) of the brain was obtained in 23 patients. These were normal in 16 patients. Seven patients had abnormalities on MRI. In three patients who had both focal epilepsy and JME, MRI demonstrated mesial temporal sclerosis in two and left parietal tumor in one. In another four patients, Chiari I malformation was detected in one, multiple sclerosis in one, asymmetry of hippocampus in one, and abnormal high intensity in the left temporal gray matter in one.

Table 1. Clinical characteristics of 26 patients
PT No. SexAge (onset)Age (EMU)Family history HistoryInitial diagnosisReason for admission MRI
  1. M, male; F, female; FC, febrile convulsion; JME, juvenile myoclonic epilepsy; TLE, temporal lobe epilepsy; P-O, parietooccipital; MTS, mesial temporal sclerosis, NA, not available.

  2. aThe onset of new type of seizures after a right temporal lobectomy for right temporal lobe epilepsy.

 1F1928YesNoFocal epilepsyDiagnosisAsymmetry of hippocampus
 2F1114NoNoFocal vs. generalized epilepsyDiagnosisChiari I malformation
 3F1314YesNoFocal vs. generalized epilepsyDiagnosisnormal
 4F1544YesNoFocal vs. generalized epilepsyDiagnosisNormal
 5M1215NoNoFocal epilepsyDiagnosisNormal
 6F 712NoNoGeneralized epilepsyDiagnosis, intractabilityNormal
 7M1319NoNoGeneralized epilepsyMyoclonic statusNormal
 8F2222NoHead traumaEpilepsyDiagnosisNA
 9F 930NoNoFocal epilepsyDiagnosis, intractabilityNA
10F 543YesNoJMEIncreased seizure frequencyMultiple sclerosis
11F1330YesNoJMEDiagnosis, intractabilityNormal
12M1723NoNoFocal vs. generalized epilepsyDiagnosisNormal
13F1416YesNoGeneralized epilepsyDiagnosisNormal
14F1232NoHead traumaFocal vs. generalized epilepsyDiagnosis, intractabilityNA
15M1040NANoFocal epilepsyDiagnosisNormal
16F1731NoNoJMEDiagnosisNormal
17M1442NoNoFocal vs. generalized epilepsyDiagnosis, intractabilityNormal
18F1131NoNoJMEDiagnosis, intractabilityNormal
19F1635NoFCFocal vs. generalized epilepsyDiagnosisNormal
20M1619NoNoGeneralized epilepsyDiagnosisNormal
21M1617NoNoFocal epilepsyDiagnosisNormal
22M1628NoFCTLEDiagnosisAbnormal high signal in the left temporal grey matter
23F1730NoNoFocal epilepsyDiagnosisNormal
24M 037NoNoFocal vs. generalized epilepsyPresurgical evaluation (intractability)Left MTS
25F18a18YesFCPostoperative seizureDiagnosisRight MTS resected
26F418YesBrain tumorLeft P-O epilepsyPresurgical evaluation (intractability)Left parietal lesion resected

Videotaped seizures in each patient were carefully analyzed. We classified each seizure type and its evolution by semiologic seizure classification (6). Semiologic focal features included; aura, version, focal tonic, focal clonic, or focal myoclonic seizure, asymmetrical tonic limb posturing during the tonic phase of GTC seizure (Figure 4 sign), asymmetry of myoclonic jerks, postictal paresis, or postictal aphasia. Figure 4 sign consists of extension of one upper limb and flexion of the other at the elbow (7). Only head turning that was unquestionably forceful, unnatural, and sustained was defined as version (8). If myoclonic jerks of only one side of the body were seen, the seizure was defined as focal myoclonic seizure. The bilateral jerking that was prominent on one side was defined as asymmetry of myoclonic jerks. Focal clinical features clearly related to focal epilepsy were excluded.

The standard 10-20 system of electrode placement was used for EEG recording. Electromyograms (EMGs) were not routinely used. Interictal and ictal EEGs of each patient were analyzed for any focal features. Focal interictal EEG findings were defined as regional or lateralized slowing (continuous, intermittent, or intermittent rhythmic), and/or regional or lateralized epileptiform discharges (spike, spike–wave complexes, or polyspikes).

Focal ictal EEG findings were defined as regional or lateralized EEG seizure patterns (spike–wave complexes; polyspikes; paroxysmal fast activity; rhythmic alpha, theta, or delta activity; or electrodecrement). Generalized epileptiform discharges with >100% voltage asymmetries were defined as maximum in the higher-voltage side.

RESULTS

  1. Top of page
  2. Abstract
  3. PATIENTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Semiology

Table 2 shows the number of analyzed videotaped seizures in each patient, seizure types, and focal features if present. A cluster of seizures was counted as one. Seventy-two seizures in 26 patients were analyzed. Focal semiologic features were observed in 12 (46%) of 46 patients.

Table 2. Semiology
PT No.Szs (n)Seizure type and evolutionFocal features
  1. GTC, generalized tonic–clonic;

  2. R, right; L, left.

  3. a Multifocal myoclonia was seen time independently.

  4. b R or L indicates the extended side.

 1 1Myoclonic (bilateral arms), L versive [RIGHTWARDS ARROW] GTCL version
 2 3L versive [RIGHTWARDS ARROW] L arm clonic [RIGHTWARDS ARROW] GTC, Myoclonic (bilateral arms) [RIGHTWARDS ARROW]GTCL arm clonic, L version, L Figure 4b
 3 2Myoclonic (bilateral arms and legs), Myoclonic (bilateral arms) [RIGHTWARDS ARROW] GTCR Figure 4 b
 4 4Myoclonic (bilateral arms, face), Myoclonic (bilateral arms, face) [RIGHTWARDS ARROW] GTCR Figure 4 b
 5 1Myoclonic (bilateral arms) [RIGHTWARDS ARROW] GTCR Figure 4 b
 6 1Myoclonic (axial)Focal myoclonia
 7 4Myoclonic (arm, neck, or shoulder) a, DialepticMultifocal myoclonic
 8 2Myoclonic (L arm), DialepticFocal myoclonic
 9 2Myoclonic (bilateral arms or L arm)Focal myoclonic
10 9Myoclonic (bilateral arms or L arm)Focal myoclonic
11 3Myoclonic (R arm), Myoclonic (bilateral arms) [RIGHTWARDS ARROW] GTCFocal myoclonic
12 1Myoclonic (bilateral arms)None
13 3DialepticNone
14 1Myoclonic (bilateral arms)None
15 3Myoclonic (bilateral arms), Myoclonic (bilateral arms) [RIGHTWARDS ARROW] Generalized clonicNone
16 3DialepticNone
17 4Myoclonic (bilateral arms and face), Myoclonic (bilateral arms, face) [RIGHTWARDS ARROW] GTCNone
18 1Myoclonic (bilateral arms)None
19 2Myoclonic (axial > arm), Myoclonic (axial > arm) [RIGHTWARDS ARROW] Generalized clonicNone
20 1Myoclonic (face and shoulder)None
21 1Myoclonic (bilateral arms), Myoclonic (bilateral arms)[RIGHTWARDS ARROW] GTCNone
2214DialepticNone
23 2Myoclonic (face, bilateral arms) [RIGHTWARDS ARROW] GTC, DialepticNone
24 1Myoclonic (bilateral arms) [RIGHTWARDS ARROW] GTCNone
25 2Myoclonic (bilateral arms)None
26 1R arm clonic [RIGHTWARDS ARROW] GTCR arm clonic, R Figure 4b

Myoclonic seizures in 22 patients were analyzed. In four of them, myoclonic jerks were seen only immediately before a GTC seizure. In two patients, no clear myoclonic seizures were recorded, although they had a history of myoclonic jerks soon after awakening. One patient did not have a history of myoclonic jerks, but she was diagnosed as having JME because of generalized epileptiform discharges on EEG and a family history of JME. Another patient had myoclonic seizures during monitoring, but videos of them were unavailable for review. Myoclonic jerks involved arms in 18 cases, axial predominant in two, face and shoulders in one, and multifocal (arms, shoulders, or neck) in one. Facial involvement was seen in four cases. Legs were involved in one case. Myoclonic jerks culminated in a GTC or generalized clonic seizure in 11 patients.

Six patients had focal myoclonic seizures. In four patients, myoclonic jerks of unilateral arms were seen. Two of them had both unilateral and bilateral myoclonic jerks. One patient had a myoclonic jerk of the neck to the right side. Another patient had multifocal jerks of head, shoulders, or arms independently.

Dialeptic seizures were seen in six patients (patients 7, 8, 13, 16, 22, and 23). The duration was short (within 20 s) in five patients (patients 7, 8, 13, 16, and 22). They stopped what they were doing (reading, eating, throwing a ball, etc). Usually, clinical manifestations were very subtle and hard to notice. One of them had lip smacking associated with a dialeptic seizure. A relatively long (>40 s) phase of unresponsiveness was seen in patient 23.

Versive seizures were observed in two patients (patients 1 and 2). Two versive seizures were recorded in patient 2. The seizures were characterized by clonic turning of her head and eyes to the left, with a duration of 5–7 s, followed by a left-arm clonic seizure. Afterward, the left arm was extended tonically, and the right arm was flexed (Figure 4 sign), and generalized stiffening and jerking followed. In two seizures, the direction of the version was consistently to the left. In another patient (patient 1), one versive seizure was recorded. Turning of the head and eyes to the left was immediately followed by a GTC seizure.

A left-arm clonic seizure was transiently seen in patient 2, as mentioned earlier. Seventeen generalized motor seizures were seen in 13 patients. Fourteen of them were GTCs, and three were generalized clonic. These were preceded by myoclonic seizures in 11 cases. In two patients, these were preceded by versive seizures. In one patient who had both JME and left parietooccipital lobe epilepsy, it was preceded by right-arm clonic seizure. In GTC seizures, the generalized tonic phase was always preceded by very brief clonic phase.

Five patients, including one patient with left parietooccipital epilepsy, had asymmetrical tonic limb posturing during GTC seizures. In one patient (patient 2), the Figure 4 sign was seen immediately after a left versive seizure. Clusters of myoclonic jerks were followed by vocalization and asymmetrical tonic limb posturing in three patients. This asymmetry persisted during the whole tonic phase. Asymmetrical posture became gradually symmetrical during following clonic phase. In one of three patients, two GTC seizures were recorded. One GTC seizure exhibited the Figure 4 sign, and another was symmetrical. Postictal paresis or aphasia was not demonstrated in any patients.

In three patients who had both JME and focal epilepsy, two (patients 24 and 26) had both generalized and focal seizures recorded during monitoring. Fourteen automotor seizures were recorded in patient 24, but these were easily distinguishable from generalized seizures. Patient 26 also had two focal seizures recorded, and right-arm clonic seizure and Figure 4 sign were seen during a generalized EEG seizure. Another patient (patient 25) had no focal features in semiology.

Interictal EEG

Generalized nonepileptiform abnormalities were seen in 11 patients (Table 3). Generalized intermittent slowing was seen in five, intermittent rhythmic slowing in five, and background slowing in one. In patient 2, intermittent rhythmic slowing in the left parietal region was seen. Asymmetry was observed in two patients (patients 25 and 26) who had undergone craniotomies for treatment of their focal epilepsy. In patient 26, who had undergone a resection of a tumor in the left parietal lobe, intermittent slowing in the left temporoparietal region was seen. Interictally, all patients had generalized epileptiform discharges such as generalized spikes, polyspikes, spike–wave complexes, or combinations of these. Polyspikes were seen in 17 patients. Spike–wave complexes were seen in 22 patients. The frequency was fast (>3.5) in seven patients, ∼3 Hz (2.5–3.5) in 14, and slow (<2.5) in one.

Table 3. EEG
PT no.Nonepileptiform abnormalities IID DistributionIctal pattern
  1. IS, intermittent slow; IRS, intermittent rhythmic slow; BS, background slow; SWC, spike-and-wave complexes (2.5–3.5 Hz); fast SWC, spike and-wave-complexes (>3.5 Hz);

  2. slow SWC, spike-and-wave complexes (<2.5 Hz); R, right; L, left; T-P, temporoparietal; BG, background.

  3. aGeneralized evolving to lateralized pattern.

 1NoneSpike, polyspikes, SWCGeneralizedPolyspikes [RIGHTWARDS ARROW] rhythmic alphaa
 2IRS generalized and regional L parietalSpike, SWCGeneralizedSpikes [RIGHTWARDS ARROW] rhythmic delta [RIGHTWARDS ARROW] rhythmic alpha a
 3IS generalizedFast SWCGeneralizedFast SWC
 4IS generalizedSpike, SWCGeneralizedPolyspikes [RIGHTWARDS ARROW] electrodecrement
 5NoneSpike, polyspikes, SWCGeneralized maximum LSWC
 6NoneSpike, polyspikes, fast SWCGeneralizedFast SWC
 7IRS generalized maximum R posteriorSpike, polyspikes, SWCGeneralizedFast SWC
 8NonePolyspikes, SWCGeneralizedPolyspikes, SWC
 9NoneSpike, polyspikes, fast SWCGeneralizedFast SWC
10IS generalizedSpike, polyspikes, SWCGeneralizedPolyspikes
11IS generalizedSpike, fast SWCGeneralizedSpike, fast SWC
12NoneSpikeGeneralized and L and R temporalSpike, slow SWC
13NoneSpike, polyspikes, SWCGeneralized, R frontalSWC
14NoneSpike, SWCGeneralizedSWC
15NoneSpike, polyspikes, fast SWCGeneralizedPolyspikes [RIGHTWARDS ARROW] electrodecrement
16NoneSpike, polyspikes, SWCGeneralizedSWC [RIGHTWARDS ARROW] paroxysmal fast
17NoneSpike, polyspikes, fast SWCGeneralizedFast SWC
18IRS generalizedSpike, polyspikes, SWCGeneralizedPolyspikes
19IS generalizedSpike, polyspikes, fast SWCGeneralizedPolyspikes, fast SWC
20IRS generalizedSWCGeneralizedSlow SWC
21NoneSpike, polyspikes, SWCGeneralizedPolyspikes
22NoneSpike, polyspikes, SWCGeneralizedSWC
23NoneSpike, polyspikesGeneralizedPolyspikes, rhythmic theta-delta
24BSSpikeGeneralized and L temporalPolyspikes
25IRS generalized, asymmetry increased beta Rslow SWC slow SWCGeneralizedPolyspikes
26IS regional L T-P, asymmetry increased BG LSpikeGeneralized and R and L frontalPolyspikes [RIGHTWARDS ARROW] rhythmic delta

One patient (patient 12) had sharp waves in left and right temporal regions in addition to generalized spikes interictally. He had no focal features in semiology. Another patient (patient 5) had generalized epileptiform discharges that were mostly maximum in the left. He exhibited the Figure 4 sign consisting of extension of the right arm and flexion of the left arm. In patient 13, a run of spikes in the right frontal region for 90 s was seen with no clinical signs (Fig. 1). Regional epileptiform discharges related to focal epilepsy were observed in two patients (patient 24 and 26), who had both focal epilepsy and JME.

image

Figure 1. Run of spikes in the right frontal region seen in patient 13. It lasted for 90 s, with no clinical signs.

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Ictal EEG

The ictal EEGs of myoclonic seizures showed generalized patterns, except for one seizure. During myoclonic seizures, polyspikes were seen in 11 patients. In two of them, polyspikes were followed by electrodecrement. Fast spike–wave complexes were seen in seven, spike–wave complexes with frequency ∼3 Hz in three, and slow spike–wave complexes in two. In two patients (patient 11 and 12), single spikes were seen on EEG associated with myoclonic seizures. In one seizure, which started with a myoclonic seizure and evolved to a GTC seizure in patient 2, the ictal EEG showed generalized spikes followed by generalized delta slowing at first (Fig. 2A). But 9 s later, it revealed rhythmic alpha lateralized to the left hemisphere (Fig. 2B). Clinically, no focal features were observed in the seizure.

imageimage

Figure 2. The ictal EEG of a myoclonic seizure evolving to a generalized tonic–clonic seizure in patient 2. A: EEG onset: Generalized spikes followed by generalized delta. B: Evolution: Rhythmic alpha lateralized to the left hemisphere appeared 9 s after EEG onset.

During dialeptic seizures in five patients, the ictal EEG showed generalized spike–wave complexes for 1 to 18 s. Because the duration of spike–wave complexes with no clinical signs ranges from 1 to 31 s, it is difficult to determine from the duration of the discharges whether the spike–wave complexes are symptomatic. In another patient who had a seizure with longer duration, generalized theta–delta activity for 44 s was seen during unresponsiveness.

The ictal EEG during two left versive seizures in patient 2 revealed generalized spikes followed by generalized rhythmic delta initially (Fig. 3A). Eighteen to nineteen seconds later, rhythmic alpha lateralized to the right hemisphere maximum in the right frontal region appeared (Fig. 3B). It evolved over the right hemisphere and then generalized. In semiology, she exhibited version to the left that was contralateral to the predominant EEG discharges.

imageimage

Figure 3. The ictal EEG of a left versive seizure evolving to a generalized tonic–clonic seizure in patient 2. A: EEG onset: Generalized spikes followed by generalized delta. B: Evolution: Rhythmic alpha lateralized to the right hemisphere appeared 18 s after EEG onset.

The ictal EEG during a left versive seizure in another patient (patient 1) revealed generalized polyspikes followed by rhythmic alpha lateralized to the right hemisphere maximum in the right frontal region.

Except for seizures described earlier, the ictal EEGs during GTC or generalized clonic seizures showed generalized patterns.

Correlation of semiology and ictal EEG

In three versive seizures of two patients, the ictal EEGs revealed generalized onset and developed lateralized activity always contralateral to the direction of the version. In one of two patients (patient 2), a left-arm clonic seizure and Figure 4 sign also were observed.

In focal myoclonic seizures of six patients, the ictal EEGs showed generalized seizure patterns.

In four GTC seizures of four patients (patients 3, 4, 5, and 26) who exhibited Figure 4 sign, no regional epileptiform discharges in the ictal EEGs were seen. In one patient who had extension of the right arm and flexion of the left arm, interictal EEG revealed generalized epileptiform discharges mostly maximum in the left.

In two patients with no clinical focal features, focal EEG findings were observed. One patient had sharp wave in the left and right temporal regions. Another had a run of spikes in the right frontal region with no clinical signs.

DISCUSSION

  1. Top of page
  2. Abstract
  3. PATIENTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

It should be stated at the outset that our patient population may have been somewhat atypical and different from the classic descriptions of JME (9). At least eight of their seizures were medically intractable, and only four patients were correctly diagnosed as having JME before monitoring. Seven patients were initially misdiagnosed as having focal epilepsy. Heterogeneity of JME also was mentioned by Dasheiff and Ritaccio (10), who reported 12 patients with medically intractable JME without video-EEG documentation. Video-EEG was crucial to establishing the diagnosis of JME in our patients.

Typical cases of JME manifest bilaterally symmetrical motor manifestations as well as interictal and ictal EEG patterns (1). Fourteen (54%) of 26 patients with JME in our series exhibited focal semiologic or electroencephalographic features or both. This is a selected population, and the percentage found will reflect only that population and not the entire population of patients with JME. This is much higher than expected; however, only very few ictal recordings have been presented in the literature.

Asymmetrical tonic limb posturing was described by Kotagal et al. (7) in the context of secondarily GTC seizures. It consists of extension of one upper limb and flexion of the other at the elbow, producing a so-called Figure 4 sign. This is a useful lateralizing sign in secondary GTC seizures, and it had not been reported in primary GTC seizures. Although Niaz et al. (11) found asymmetry or asynchrony in the clonic phase of GTC seizures in patients with idiopathic generalized epilepsy (IGE), the tonic phase was always symmetrical in their report. In our study, the Figure 4 sign was seen in five (19.2%) of 26 patients. In three of them, it persisted during the whole tonic phase. Although the Figure 4 sign has a good lateralizing value in focal-onset GTC seizures, appearance of this sign should not preclude the diagnosis of a generalized epilepsy. The frequency of this sign in primary GTC seizures must be explored further in a larger, unselected group of patients. However, most JME patients do not undergo video-EEG monitoring.

Although versive seizures are typically seen in patients with focal epilepsy, reports of versive or circling seizures have been mentioned in some patients with JME (12) or IGE. Gastaut et al. (13) noted versive or circling epilepsy in patients with 3-Hz spike–wave complexes and postulated functional imbalance of generalized cerebral hyperexcitability to explain this phenomenon. Aguglia et al. (14) also reported versive seizures in four of 16 patients with IGE. The ictal EEG during 13 versive seizures from these four patients showed a generalized EEG pattern. Niaz et al. (11) also found adversive head turning in six of 10 GTC seizures in patients with IGE. In these reports, however, a strict definition of version was not used. In our study, we defined version as head turning that is unquestionably forceful, unnatural, and sustained (8). We observed definite version in two of 26 patients. Version observed in these versive seizures was indistinguishable from that seen in patients with focal epilepsy. The direction of version in one patient who had two versive seizures during monitoring was consistently to the left. The ictal EEG in these seizures revealed generalized EEG onset followed by lateralized evolution over the side of the right hemisphere (contralateral to the direction of version). Left-arm clonic seizure was seen transiently with in one versive seizure, although the possibility of coexistent generalized epilepsy and focal epilepsy cannot be completely ruled out, it is more likely that they had JME with focal features because they exhibited generalized interictal epileptiform discharges, generalized ictal EEG onset, no other seizure types suggesting focal epilepsy, and a good response to antiepileptic drug (AED) treatment appropriate for JME. Therefore the occurrence of version does not preclude the diagnosis of JME.

Focal myoclonic seizures were recorded in six patients. The accompanying ictal EEGs revealed a generalized seizure pattern. Unilateral myoclonic jerks may lead to misdiagnosis because these jerks could be misinterpreted as simple partial seizures (4,5). In our series, three patients were thought to have unilateral jerking by history, and two of them were initially diagnosed to have focal epilepsy. Two patients with history of focal myoclonic jerks in the monitoring unit had actually bilateral jerking on the videos. Oguni et al. (15) reported asymmetry of myoclonic jerks in four of five patients with JME. They also stated that patients may perceive asymmetry in some of the symmetrical jerks.

Interictal EEG in one patient showed sharp waves in right and left temporal regions, and another had a run of spikes in the right frontal region as well as generalized epileptiform discharges. From the viewpoint that primarily generalized epileptic discharges are supposed to be symmetrical, synchronous, and global, these focal EEG abnormalities are unusual. In addition, one patient who had versive seizures had intermittent rhythmic slowing in the left parietal region on EEG. Several authors reported focal or asymmetrical EEG abnormalities or both. Focal EEG discharges were described in 56% of patients with IGE by Lombroso (16). He suggested possible mechanisms including associated focal cortical pathology such as microdysgenesis (17), and development of localized, self-sustaining hyperexcitability in low-threshold cortical structures subjected to repeated generalized epileptiform activity. Although these hypotheses are attractive, no definitive explanation of these focal abnormalities exists. According to the Cortical Theory, which owes it origin to the Telencephalic Theory by Harbaugh and Wilson (18), the cortex is diffusely excitable. This theory may explain focal epileptic discharges in patients with IGE. Focal EEG findings are thought to be causes of misdiagnosis. We must be aware of these focal electroencephalographic features in JME or IGE.

Three of our patients had both JME and focal epilepsy. In two of them, primary generalized epilepsy developed after resection for treatment of focal epilepsy. Coexistence of generalized and focal epilepsies is infrequent but should be kept in mind (19). Two of these three patients had a family history of epilepsy, indicating that genetic factors play a role.

Focal clinical or EEG features or both in patients with JME are common. These features include not only unilateral myoclonic jerks but also version and asymmetrical tonic limb posturing. Focal EEG features also are seen, although the mechanism is unclear. One must be aware of potential pitfalls when taking the history from patients with JME or in reviewing their interictal and ictal EEGs. Video-EEG monitoring is invaluable in establishing a correct diagnosis and choosing effective AED therapy.

REFERENCES

  1. Top of page
  2. Abstract
  3. PATIENTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES