Lifelong and new nocturnal events found to be right frontal lobe epilepsy secondary to a cortical dysplasia
Article Outline
- 1. Introduction
- 2. Case description
- 3. Video and image analysis
- 4. Discussion
- Disclosures
- Appendix A. Supplementary data
- References
- Copyright
1. Introduction
Frontal Lobe seizures (FLE) are frequently mistaken for psychogenic non-epileptic seizures (PNES) and other imitators of epilepsy as well as complex sleep related movement disorders and other parasomnias. In FLE, the EEG can often be obscured by artifact, it can be non-localizing, non-lateralizing or the electrographic seizure activity may simply not be seen on scalp recording due to the ictal onset being distal (deep) to the surface recording leads [1], [2]. Therefore, making the diagnosis is heavily dependent on clinical history and capturing several of the patient’s typical spells utilizing video polysomnography (vPSG) or video EEG monitoring (vEEG) with careful review of the semiologic features of the events in question. In this atypical case the etiology of a patient’s lifelong seizure disorder was discovered when, at the later age of 60, her typical events changed in semiology and frequency [3].
2. Case description
A 60-year-old right-handed woman presented to Mayo Clinic Arizona (MCA) with a lifelong diagnosis of epilepsy who had her first seizure at age four without definitive etiology or localization. In February 2008, she was seen at MCA about a “new type” of nocturnal event different from her typical monthly lifelong nocturnal and diurnal seizures. She denied any family history of epilepsy.
Her husband described her typical nocturnal seizures in the past as lasting 1–2
min and occurring out of sleep with initial body stiffening followed by clonic activity. Postictally she would fall back asleep and remain amnesic of her typical nocturnal seizures.
The “new” nocturnal spells began eight months prior to admission. She was having 14 of these spells a month, 30min to 1h after sleep onset or in the early morning hours lasing 15–20s. Unlike her typical seizures, she was able to recall the onset of some of these events such as cramping up of the legs followed by “back and forth” movements of her lower extremities. Her husband described an initial “guttural cry,” body stiffening with eyes wide open and increased salivation. She was taking phenytoin 250mg daily and zonisamide 400mg daily and had tried levetiracetam, lamotrigine, valproate and gabapentin in the past, but all were ineffective. Her physical and neurological examinations were normal. Serologic screening, two previous brain MRIs in 1999 and 2007, and routine EEG were all normal.
3. Video and image analysis
During the vEEG monitoring, seven of the patient’s typical nocturnal events were captured. The vEEG recording revealed brief 1–1.5min spells occurring out of stages 1 and 2 non-rapid eye movement (NREM) sleep with an abrupt arousal with brief hyperkinetic leg movements and restless body motion at onset, followed by head and eye version leftward and bicycling movements of her lower extremities. After a 5s arrest of motor activity she had dystonic posturing of her left hand and arm followed by a few brief left arm and right leg (cruciate) rhythmic clonic jerks, finally becoming bilaterally generalized (left greater than right) with gradual slowing of the motor events. All seven seizures captured were stereotypical and compatible with FLE due to a focus in the right frontal lobe.
Interictal EEG recording revealed rare right frontal spikes; ictal EEG was non-localizing and non-lateralizing with diffuse rhythmic theta (3.5–7.5Hz) activity seen at seizure onset or, alternatively, the onset was obscured by muscle artifact (Fig. 1). In the repeat head MRI with seizure protocol (1.5-T MRI image with thin, oblique coronal sections), axial T2 fast spin echo (Fig. 2) and coronal T2 sections (Fig. 3) showed a lesion in the right frontal lobe consistent with cortical dysplasia. The patient was discharged home on newly started oxcarbamazepine (150mg twice daily to titrate to 300mg twice daily over the next two weeks) and zonisamide (continued at 400mg daily), and her phenytoin was discontinued. The patient refused any further evaluation for pre-surgical studies.
Fig. 1.
EEG at seizure onset reveals only muscle and movement artifact.
Fig. 2.
MRI head, axial T2 fast spin echo.
Fig. 3.
MRI head, coronal T2 obl/stir.
4. Discussion
FLE patients can demonstrate bizarre motor behaviors with occasional preservation of consciousness (supplementary motor seizure) and can thus be misdiagnosed as a parasomnia or psychogenic seizure. As a result, FLE patients may go years without proper diagnosis or treatment. Due to the volume of the frontal lobe, scalp electrode coverage for EEG recording is sometimes limited. In many cases, the ictal and interictal EEGs are normal [1], [2] or obscured by muscle artifacts [1].
O’Brien et al. found no single piece of historical data or single video recorded semiologic feature to be sufficient to clearly distinguish frontal from temporal lobe epilepsy [4]. Therefore, an in-depth history of the patient’s typical event, careful review of multiple typical seizures captured during vEEG or vPSG monitoring, along with high-resolution neuroimaging are often essential for diagnosis [4]. Seizure protocol MRI imaging in our patient revealed a right frontal lesion highly suggestive of a Taylor focal cortical dysplasia which has recently been confirmed statistically to be strongly associated with sleep related epilepsies [5]. The other important feature in our patient is the emergence of typical nocturnal hypermotor frontal lobe seizure at the age of 60years after lifelong nocturnal and rare diurnal seizures. This pattern of evolution suggests that it is possible to have different nocturnal seizures at different ages in the same patient. If a nocturnal epilepsy, including FLE is suspected, the full EEG seizure montage (utilizing fronto polar, temporal and parasagittal electrode chains), instead of the usual PSG montage [6], should be utilized and reviewed at a speed of 10s per monitor page for better diagnostic yield. Seizures in sleep misdiagnosed and left untreated may not only increase sleep fragmentation and decrease sleep efficiency, but can also subsequently exacerbate and increase seizure frequency [7]. In addition, delayed diagnosis of nocturnal epilepsies may possibly place the untreated patient at greater risk for sudden unexpected death in epilepsy [8]. With a comprehensive pre-surgical workup, resective surgery may provide excellent outcomes for many with intractable and debilitating nocturnal frontal lobe epilepsy secondary to a Taylor cortical dysplasia [9].
Disclosures
Dr. Katherine Noe has received research grants from NeuroPace, Inc. and from Eisai, Inc.
All other authors have nothing to disclose and no conflicts of interest.
Appendix A. Supplementary data
Supplementary data.
References
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PII: S1389-9457(09)00346-3
doi:10.1016/j.sleep.2009.08.005
© 2009 Elsevier B.V. All rights reserved.
