Functional Magnetic Resonance Imaging Identifies Abnormal Visual Cortical Function in Patients with Occipital Lobe Epilepsy

PURPOSE: To determine whether functional magnetic resonance imaging (fMRI) can reliably identify lateralized cortical dysfunction in patients with suspected occipital lobe epilepsy. METHODS: We compared visual cortical function of 10 patients with intractable occipital lobe epilepsy with nine control subjects' fMRI. Visual stimulation by using an alternating checkerboard pattern results in transient increases in the intensity of the proton magnetic resonance signal of water in the occipital lobes during echo-planar imaging. We used these stimulus-dependent changes in signal intensity to construct functional activation maps, which we registered onto anatomic images. RESULTS: After full-field stimulation, none of the patients with occipital lobe epilepsy had normal activation patterns, whereas eight of the nine control subjects had normal patterns (p = 0.001). Abnormalities consisted of either a markedly asymmetric activation pattern in six of 10 patients (p = 0.04), or a complete absence of activation in four of 10 patients (p = 0.05). The abnormal side of activation was concordant with the side of seizure onset in all six patients with asymmetric activation maps. Half-field stimulation produced less reliable results. Although more patients had abnormal activation maps than did controls with half-field stimulation (p = 0.04), the abnormal side was discordant with the side of seizure onset in three of the five patients who had markedly asymmetric activation patterns. CONCLUSIONS: These results suggest that fMRI with full-field stimulation is a reliable, noninvasive method for identifying areas of abnormal visual cortical function ipsilateral to the epileptogenic region in patients with occipital lobe epilepsy.     

Occipital Lobe Developmental Malformations and Epilepsy: Clinical Spectrum, Treatment, and Outcome

Summary: Purpose : Cortical developmental malformations (CDM) are increasingly recognized in association with epilepsy. We describe 10 patients (age range 14–35 years) with symptomatic occipital lobe epilepsy and CDM.
Methods : Neurologic, neuroophthalmologic and electro-physiologic studies were performed. Patients had MRI, SPECT, and in some cases intracranial EEG investigators.
Results : Mean age of seizure onset was 8 years. We noted strong correlations between the presence of visual auras, the scalp EEG pattern, and the subtype of underlying pathology. Magnetic resonance imaging (MRI) showed CDM in all patients, with polymicrogyria and focal dysplasia being the most frequent malformations. Despite the presence of occipital lobe structural malformations in all patients, visual field deficits were present in only 2. Those who underwent cortical resections were seizure–free or showed major improvement at a mean follow–up of 3.5 years.
Conclusions : Intracranial stimulation studies and the low frequency of pre- and postoperative deficits suggest that some degree of cortical visual reorganization may occur in patients with occipital lobe malformations. Occipital lobe CDM should be sought as a cause of symptomatic occipital lobe epilepsy even though they may become symptomatic after childhood.     

Transitory and permanent visual field defects induced by occipital lobe seizures

Visual field defects are rarely associated with epilepsy. We report two patients with a long history of cryptogenetic occipital epilepsy. Both patients suffer complex partial crises accompanied by concentric reduction of the visual field followed, in the first one, by a prolonged left homonymous hemianopsia, and in the second one, by a permanent right inferior quadrantopsia. Occipital and occipito-temporal epileptic activity has been registered between seizures in both patients, and in one patient also during the seizure itself. Differential diagnosis has been considered, especially with migraine.     

A case with atypical childhood occipital epilepsy "Gastaut type": an ictal migraine manifestation with a good response to intravenous diazepam

We report the history of a 14-year-old girl with atypical childhood occipital epilepsy "Gastaut type" whose first generalized tonic-clonic seizure was preceded by migraine without aura and followed by a status migrainosus. This status lasted for 3 days despite standard analgesic therapy. An EEG recording revealed an occipital status epilepticus during her migraine complaints. Seven minutes after intravenous administration of 10 mg diazepam under continuous EEG recording, a suppression of the epileptiform discharges over the right occipital was seen, while the headache subsided 3 min later. After precise questioning about the circumstances that possibly could have led to these events, it appeared that she had played for hours with a play station on the new color TV and she had visited an exhibition of Matisse and Bonnard with bright colors and contrast-rich text. Standardized extensive intermittent photic stimulation (IPS), 2 days after the status migrainosus, evoked besides asymmetrical right-sided driving, green spots in her left visual field, while in the EEG sharp waves were recorded over the right parietotemporal region. After further IPS with 20 Hz (eye closure), she started complaining of a light pulsating headache right occipitally and in the EEG right parietotemporal sharp-waves were seen. This lasted for about 10 min. Later, an interictal routine EEG was normal except for some theta over the right temporooccipital area. The most likely diagnosis is an atypical form of occipital epilepsy "Gastaut type." We would therefore advocate recording EEGs with photic stimulation in patients with atypical migraneous features.     

Ictal visual hallucination intermittent photic stimulation: using evaluation of the clinical findings, ictal EEG, ictal SPECT, and rCBF]

A 43-year-old, right-handed woman experienced right hand paresthesias and a visual field abnormality. We attributed her symptoms to psychiatric abnormalities, due to the presence of delusions and auditory hallucinations. Upon photostimulation, she experienced left visual field hallucinations and demonstrated slow waves on the right parieto-occipital regions. The clinical and electro-encephalographic findings suggested that these episodes were epileptic seizures originating from the right occipital region. Ictal fear appeared at the end of the seizure, reflecting the spread of seizure activity to the mesial temporal region. Ictal SPECT images showed hyper-perfusion in the right occipital region and left cerebellar cortex. rCBF in the occipital lobe was significantly asymmetrical. When we encounter an epileptic patient with psychosis who has a visual hallucination, we should consider the possibility of epileptic seizure originating from the occipital lobe.     

Memory performance following unilateral electrical stimulation of the hippocampus in a child with right temporal lobe epilepsy

Verbal and visual memory performance was evaluated during unilateral stimulation of the hippocampus in an 11-year-old child with complex partial epilepsy associated with a right mesial temporal lobe focus. Memory was assessed during left and right hippocampal stimulation as well as preoperatively and 6-months postoperatively following anterior temporal lobe resection including removal of the anterior portion of the hippocampus. Stimulation of the left hippocampus resulted in a mild to moderate decrement in both verbal and visual memory performance as compared with a right hippocampal stimulation. In addition, stable or improved performance on memory assessment as well as general neuropsychological evaluation was noted 6 months postoperatively. Taken together, these data suggest that, in this child with early seizure onset (8 months of age), visual learning/memory functions shifted to the contralateral hippocampus and associated structures following damage to the right mesial temporal lobe structures. In addition, verbal learning/memory continues to be mediated by the left hippocampus, as expected. Thus, it appears that, as in the case of language lateralization, there may be a distinct subset of temporal lobe seizure patients (i.e., early seizure onset, high seizure frequency, chronic duration) in whom the brain has the capacity to shift material-specific memory functions to the contralateral mesial temporal lobe structures.     

Celiac Disease, Bilateral Occipital Calcifications and Intractable Epilepsy: Mechanisms of Seizure Origin

Summary: Purpose: To elucidate the mechanisms of seizure origin in patients with celiac disease and bilateral occipital calcifications (CEBOC). Individuals with CEBOC frequently present with occipital lobe seizures, but additional lesions and additional attack patterns may occur.
Methods: We studied two men and one woman who had CEBOC. Villous atrophy was revealed in the two patients who underwent duodenal biopsy. All had a comprehensive presurgical evaluation, including prolonged video-EEG recordings. Two had magnetic resonance imaging (MRI) with volumetric study of mesial temporal structures (MRIV). One patient had undergone stereotactic intracranial depth electrode studies (SEEG).
Results: All patients presented with intractable complex partial seizures. Two had partial simple seizures with visual aura. Neurologic examination was normal; one was of normal intelligence, and two were mildly retarded. Neuroimaging studies showed that each had bilateral occipital calcifications as well as epileptiform abnormalities over temporal lobes. In one, MRI showed an additional right frontal lesion, but SEEG demonstrated right occipital lobe seizure origin with anterior spread; this male patient later underwent a right occipital lobe resection. Another with a history of prolonged febrile convulsions had bilateral hippocampal and amygdalar atrophy demonstrated by MRIV.
Conclusions: In one patient, SEEG confirmed that seizures originated in the occipital lobe. The presence of dual pathology was demonstrated in another, raising the possibility of both occipital and temporal seizure onset. The presence of extraoccipital lesions or of mesial temporal atrophy requires SEEG for clarification of seizure onset. In the absence of confounding factors and when laterality can be demonstrated, surgical treatment may be considered.     

A case of right mesial temporal lobe epilepsy accompanied with ictal polyopsia]

A 59-year-old, right-handed woman had a paroxysmal polyoptic visual illusion, in which multiple copies of the object she saw spread horizontally in the left hemi-visual field. Polyopsia appeared for a few seconds. Neurological examination was normal. Magnetic resonance imaging (MRI) showed a tumor-like lesion involving the cortical and subcortical matters in the right mesial temporal regions. An interictal EEG showed frequent spikes in the right mesial temporal area and intermittent theta waves in the right fronto-temporal area. Video-EEG monitoring using the sphenoidal electrodes showed the seizure discharges originating in the right sphenoidal lead accompanying the polyoptic visual illusion. The seizure discharges were restricted within the right mesial temporal lobe. Paroxysmal visual illusion disappeared after administration of anti-epileptic drugs. EEG showed rare spikes in the right mesial temporal area. Polyopsia in this patient presumed to be associated with right mesial temporal lobe epilepsy because polyopsia and seizure activities on the ictal EEG were coupled and polyopsia ceased after administration of anti-epileptic drugs. Polyopsia is recognized as visual perseveration in space and a rare visual illusion. The lesion causing polyopsia has been reported to be mostly within posterior cerebral areas including occipital, parietal and temporal regions. This patient whose ictal polyopsia associated with mesial temporal lobe epilepsy is a very rare case because most reported cases presenting ictal polyopsia are neocortical temporal lobe epilepsy. The precise mechanism of polyopsia remains unknown. The mesial temporal lobe includes the hippocampus and parahippocampal formation that have been reported to receive information from the diverse association cortex and work as memory controllers. Ictal polyopsia may result from dysfunction of the visual association cortex or visual memory systems induced by the epileptic activities in the mesial temporal lobe. Polyopsia is a rare ictal semeiology of mesial temporal lobe epilepsy and may be one of the important ictal symptoms.     

Coeliac disease, unilateral occipital calcifications, and drug-resistant epilepsy: successful lesionectomy

Purpose – To draw attention to the triad of coeliac disease (CD), occipital calcifications, and drug‐resistant epilepsy, with focus on the outcome of epilepsy surgery. Methods – We describe a male patient who despite a diagnosis of CD from the age of 9 did not comply with the gluten‐free diet. At the age of 11 he developed simple and complex partial seizures with visual symptoms, anxiety, and ambulatory automatisms. His epilepsy appeared to be drug resistant, and after having tried nine antiepileptic drugs (AEDs), alone or in combinations, he underwent a presurgical evaluation at the age of 30. Interictal standard electroencephalograms (EEGs) disclosed frequent biparieto‐occipital epileptiform discharges. Computed tomography showed cortical–subcortical punctate calcifications in the right parieto‐occipital region, where his seizures seemed to start, according to ictal EEG registrations from intracranial strip electrodes. Results – At the age of 31 he underwent epilepsy surgery. A 5 × 6 cm large area of the right parieto‐occipital region was resected, including the area with calcifications. Except for a few short‐lasting episodes of anxiety (simple partial seizures?) he has now been seizure‐free for 12 years. AEDs were withdrawn 5 years ago. Postoperatively he was left with an upper left‐sided quadrant anopsia, which is not bothering him. Conclusions – In patients with CD, unilateral occipital calcifications, and drug‐resistant epilepsy, epilepsy surgery should be considered, as a lesionectomy might be very successful.     

Partial Seizure with Aphasic Speech Arrest Caused by Watching a Popular Animated TV Program

On the evening of December 16, 1997, about 700 children across Japan were hospitalized because of convulsive seizures or vomiting experienced while watching a popular animated TV program that included blue and red stimuli that alternated at 12 flashes per second. In one case, an 11-year-old girl developed a hallucination in the right visual field and a subsequent cramp on the right side of her face, with aphasic speech arrest. She had no history of seizures. Her electroencephalogram (EEG) showed normal background activity and no epileptiform discharges. Intermittent photic stimulation provoked a photoparoxysmal response. Her main clinical manifestation was a TV-induced left occipital lobe seizure spreading toward the left inferior frontal lobe. This suggested a functional link from the occipital lobe to the frontal operculum.     

Imaging of propagated sites of epileptic discharges in repeated 123I-IMP SPECT scans

Single-photon emission computed tomographic (SPECT) brain scans with N-isopropyl-(iodine-123-p-iodoamphetamine (123I-IMP) were performed twice at an interval of about 2.5 years in the interictal period in an adult patient with occipital-lobe epilepsy. The first SPECT scan showed an abnormal image of decreased 123I-IMP uptake in the right occipital lobe. This abnormal image was regarded as the primary focus of his epilepsy on the basis of its regional agreement with right-occipital spikes consistently seen in interictal electroencephalographic recordings throughout his clinical history. In the second scan, he showed multiple abnormal images of decreased uptake in the right frontotemporal lobes and left occipital lobe together with the right occipital lobe. These additional abnormal images were considered to be propagated sites of epileptic discharges.     

Hyperglycemia with occipital seizures: images and visual evoked potentials

PURPOSE: Hyperglycemia may rarely be seen with visual seizures. Observation of both visual evoked potentials (VEPs) and magnetic resonance imaging (MRI) in visual status epilepticus (SE) has not been reported. We describe acute and follow-up VEP and MRI findings of a patient with hyperglycemia-related visual SE of occipital origin. METHODS: In a 59-year-old diabetic woman, complex visual hallucinations and illusions developed with < or =10 seizures per hour as an initial manifestation of nonketotic hyperglycemia. RESULTS: Neurologic examination revealed ictal nystagmus to the right and continuous right hemianopsia. Ictal electroencephalography (EEG) and Tc-99m hexamethylpropylene amine oxime (HMPAO) single-photon emission computed tomography (SPECT) revealed an epileptogenic focus in the left occipital lobe. MRI with fluid-attenuated inversion recovery showed focal subcortical hypointensity and gyral hyperintensity. Follow-up MRI showed only minimal gyral hyperintensity at 6 months. The P100 amplitude of VEP was significantly higher at the right occipital area during SE, but slightly higher on the left after the patient had been seizure free for 6 months. CONCLUSIONS: Occipital seizures and hemianopsia can be caused by hyperglycemia and may be accompanied by special MRI and VEP findings.     

Complex visual hallucinations after occipital cortical resection in a patient with epilepsy due to cortical dysplasia

BACKGROUND: Charles Bonnet syndrome is a rare disorder characterized by complex and recurrent visual hallucinations in elderly patients with visual pathway pathologic defects. To date, to our knowledge, it has not been described in patients undergoing surgical resection for occipital lobe epilepsy due to cortical dysplasia. OBJECTIVE: To describe a patient who experienced complex visual hallucinations following resection of cortical dysplasia on the right occipital lobe and who was diagnosed as having Charles Bonnet syndrome. PATIENT: A 35-year-old woman underwent surgical resection for medically intractable epilepsy caused by cortical dysplasia involving the right occipital lobe. RESULTS: Two months after resection of the epileptogenic zone, complex visual hallucinations in the left visual field not associated with loss of consciousness or delusion developed in the patient. Hallucinations persisted for more than 12 months despite treatment with antiepileptic medications. During hallucination, no electrographic seizures were recorded through long-term video-electroencephalographic monitoring. CONCLUSIONS: Charles Bonnet syndrome may occur in a patient with occipital lobe epilepsy following resection of the diseased brain with a developmental malformation. Charles Bonnet syndrome associated with surgical treatment of occipital lobe epilepsy may have been overlooked.     

An unusual case of epilepsy exhibiting gelastic seizure, simple visual hallucination, and transient swelling of the left parieto-occipital region]

We report a 74-year-old man with gelastic seizure, simple visual hallucination, and adversive seizure. The patient described his visual hallucinations as "rotating light like a firefly" and "mimicking a stream". Brain CT scan showed a transient swelling as well as low density of a left parieto-occipital region. Electroencephalographic study revealed spikes and fast waves beginning at left occipital region. Although temporal lobe and hypothalamic lesions (especially hypothalamic hamartomas) are well known as origins of gelastic seizures, we could not find any report that described a series of occurrence of gelastic seizure and simple visual hallucination. Usually, simple visual hallucination is thought to occur in occipital lesion. In our case, it is possible that gelastic seizure and simple visual hallucination are related to the epileptic discharge from occipital lesion directly or indirectly. The reversible brain swelling with low density seen in the present case might be caused by cytotoxic edema due to status epilepticus.     

Visual field plasticity in a female with right occipital cortical dysplasia

Brain plasticity refers to its ability to recover after damage. Visual field plasticity is not well recognized. We report a 12-year-old female who first presented with recurrent seizures and was subsequently found to have a large, right occipital cortical dysplasia on magnetic resonance imaging. Her visual field by Goldmann perimetry was totally normal. Visual-evoked potential studies revealed the left hemifield P100 response was detected maximally at the right temporal and parietal regions. A weak but reproducible right hemifield P100 response was located at the right medial skull base. Functional magnetic resonance imaging with flashlight stimulation revealed cerebral activity mainly at the right posterior temporal and parietal lobes and left occipital lobe. These studies suggested that the left hemifield function was located at the right posterior temporal and parietal lobes. The left occipital lobe may also have been reorganized, with a P100 vector pointing out from its inferiomedial base. We reviewed other related reported cases. We believe that visual-evoked potential studies and visual functional magnetic resonance imaging should be performed more liberally for recognition of visual field plasticity.     

Tailored resections in occipital lobe epilepsy surgery guided by monitoring with subdural electrodes: characteristics and outcome

PURPOSE: Occipital lobe epilepsy is uncommon in epilepsy surgery series and often difficult to assess due to rapid seizure propagation, misleading seizure semiology and confounding interictal epileptiform activity. Ictal recordings with surface electrodes may not define properly the seizure onset zone in surgical evaluation for intractable occipital epilepsy. Specially in dysplastic lesions, the extension of the epileptogenic zone is not well defined by neuroimaging techniques, therefore, implantation of intracranial electrodes is often indicated. In this study we present our experience with individually tailored resections of occipital lobe epileptic foci guided by monitoring with subdural electrodes. METHODS: Data from interictal and ictal surface and intracranial recordings, neuroimaging, surgical treatment, pathology and outcome of seven patients are presented. RESULTS: The most common seizure type (6/7 patients) was complex partial with temporal lobe semiology, five patients experienced visual auras as part of their complex partial seizures or as separate simple partial seizures. Two patients had seizures suggesting supplementary motor area involvement. One patient had temporal as well as frontal seizure propagation. Neuroimaging showed lesions in 6/7 patients. Pathological studies revealed cortical dysplasia and tumors as the most common causes. Intracranial recordings (6/7 patients) revealed focal onset in 2 patients, regional onset in 2, and diffuse onset in 2. Surgery was performed according to intracranial recordings restricting resections in cases with focal seizure onset (even in large dysplastic lesions) and performing wider resections in patients with regional or diffuse onset. Five of seven patients are seizure free after 12-55 months (mean 24.3). The two remaining patients may be classified as Engel 2b and 3a. CONCLUSIONS: This series of occipital lobe epilepsy surgery shows that, even in patients with cortical dysplasias, restricted resections may have a good outcome and that intracranial monitoring is usually necessary in order to design an individually tailored resection.     

Focal Cerebral Magnetic Resonance Changes Associated with Partial Status Epilepticus

Summary: We report 2 patients with transient abnormalities on magnetic resonance imaging (MRI) associated with partial status epilepticus (SE). A man with a 4-month history of partial seizures had complex partial SE for 9 days, with left temporal maximum on ictal EEG. Left temporal lobe T₂ signal was increased on MRI during SE, but cerebral MRI was normal 9 weeks later. A woman with "cryptogenic" temporal lobe epilepsy for 16 years had complex partial SE for 1 week, with right temporal maximum on ictal EEG. T₂ Signal was increased over the entire right temporal lobe, extending into the insula, without mass effect, on MRI 1 month after SE ended. Repeat MRI 1 month later showed marked decrease in volume of increased T₂ intensity, without gadolinium enhancement, but with mild mass effect over the right anteroinferomesial temporal areas. A gemistocytic astrocytoma was resected. Focal cerebral MRI abnormalities consistent with cerebral edema may be due to partial SE but also may indicate underlying glioma, even in long-standing partial epilepsy. Focal structural imaging changes consistent with neoplasm should be followed to full resolution after partial SE.     

选择性海马切除在枕叶癫痫手术中的应用

目的 总结分析枕叶癫痫患者手术中联合选择性海马切除的手术治疗效果和经验.方法 回顾性分析2003年1月至2006年12月在我科接受手术治疗的20例向颢叶内侧传导的枕叶癫痫病例,统计患者的发病、检查及手术治疗情况,并介绍相关手术体会.17例(85%)为部分性发作继发强直.痉挛性发作为主,9例有颢叶先兆或口咽自动症,PET检查中9例有颞叶的代谢异常,MRI及MRS共发现有海马异常13例;脑电图确定癫痫灶位于枕叶外侧皮层8例.内侧皮层6例,枕颞交界区6例,发作期脑电图均显示明显向颢叶传导.手术均行枕叶致痫灶切除和经颞底海马结构切除术.结果 癫痫发作Engle分级示:I级16例,Ⅱ级2例,Ⅲ级2例.出现视野损害3例;推理智商无明显变化15例,下降4例,改善1例.结论 向颞叶传导为主的枕叶癫痫常可以有颢叶的先兆或自动症,并有影像学的异常,手术联合枕叶致痫灶切除和经颞底海马结构切除术,手术效果好.     

Ictal MEG in two children with partial seizures

We report on the successful identification of epileptic foci in two children with partial epilepsy using ictal magnetoencephalography (MEG). Case 1 is a 12-year-old male suffering with simple partial seizures with leftwards nystagmus. Ictal SPECT revealed a hyperperfusion area in the right lateral occipital area, and MRI revealed cortical dysplasia in the same area. Interictal EEG dipoles were concentrated in the right mesial occipital lobe. Both interictal and ictal MEG dipoles were concentrated in the right mesial occipital lobe, which corresponded well with neuroimaging data and his clinical features. Case 2 is a 5-year-old female suffering with simple partial seizures with left-side facial twitching. Interictal EEG dipoles were located in her left motor area, the pre-sylvian fissure, close to the location of the interictal MEG-estimated dipoles. Ictal EEGs showed no remarkable changes associated with her clinical manifestations. However, ictal MEG showed high-voltage slow waves over her left hemisphere, and ictal MEG iso-contour maps revealed a clear dipolar pattern, which suggested that the MEG dipole was located in the area of the sylvian fissure. Ictal SPECT revealed hyperperfusion areas around the left sylvian fissure. Conclusion: Ictal MEG is useful for determining the precise location of epileptic focus in patients with motionless seizures, including children.     

The preserved temporal crescent: the clinical implications of an "endangered" finding.

Sixteen consecutive patients with a partially or completely preserved temporal crescent (PTC) in right or left eye were identified by Goldmann kinetic perimetry. PTC etiologies were stroke, birth injury, trauma, aneurysm, and migraine. PTC eludes detection by automated static perimetry of the central visual field, but its ascertainment with Goldmann perimetry usually implies contralateral occipital lobe ischemia sparing a small portion of anterior primary visual cortex.