Visualizing prolonged hyperperfusion in post-stroke epilepsy using postictal subtraction SPECT

Diagnosis of post-stroke epilepsy is often challenging because of a low incidence of epileptiform abnormalities on electroencephalography (EEG). Hence, this study evaluated whether postictal subtraction single-photon emission computed tomography (SPECT) could visualize epileptic activity and act as a diagnostic modality in post-stroke epilepsy. Fifty post-stroke epilepsy patients, who had undergone Tc-99m-ECD SPECT twice (postictal and interictal), were enrolled. The postictal hyperperfusion area was identified by subtraction (postictal–interictal) SPECT and classified into two distribution types: superficial or deep-seated. Laterality and distribution of postictal hyperperfusion on subtraction SPECT were compared with stroke lesions, seizure symptoms, and epileptiform EEG findings. Forty-three of the 50 patients (86%) had hyperperfusion on subtraction SPECT and 26 (52%) had epileptiform EEG findings. Subtraction SPECT showed prolonged postictal hyperperfusion despite the relatively long interval between seizure end and postictal SPECT (median: 19.1 h, range: 2.2–112.5 h). The laterality of the hyperperfusion area had a high concordance rate with the laterality of stroke lesions (97.7%), seizure symptoms (91.9%), and epileptiform EEG findings (100%). Scalp EEG identified epileptiform activity more frequently in superficial type of SPECT, but less frequently in deep-seated type (both, P = 0.03). Postictal SPECT can be complementary to scalp EEG in endorsing the diagnosis and location of post-stroke epilepsy.     

SPECT in a patient with postictal PLEDs: is hyperperfusion evidence of electrical seizure?

The pathophysiological relation between periodic lateralized epileptiform discharges (PLEDs) and epileptic seizures is not known and the exact causative mechanism of PLEDs still remains unclear. In this report, the authors present a case in which the EEG displayed PLEDs after a complex partial seizure. This patient, with a long history of complex partial seizures, had previously undergone right standard anterior temporal lobectomy with hippocampectomy, with a diagnosis of mesial temporal sclerosis. She had one complex partial seizure 72 days after operation and was admitted to hospital. Her brain MRI revealed changes due to temporal lobectomy and small residual posterior hippocampic anomalies. PLEDs over the right temporal lobe were seen in postictal EEGs and persisted for 4 days despite the patient's normal mental status and normal neurologic examination. Brain perfusion scintigraphy with Tc-99m-HMPAO during PLEDs was performed on the second day after the seizure, and right temporal hyperperfusion was detected. EEGs and scintigraphic imaging were repeated after cessation of PLEDs. The repeated brain scan displayed right temporal hypoperfusion. PLEDs during the postictal period may actually be an ictal pattern, and if hyperperfusion in the brain SPECT studies during PLEDs is seen, further aggressive antiepileptic drug therapy may be necessary in some cases.     

Crossed cerebellar hyperperfusion on ictal FDG PET in astrocytoma

Crossed cerebellar hyperperfusion (CCH) is a rare phenomenon and reflects the close anatomical and functional relationship between the frontal brain region and its mediated remote effect on the contralateral cerebellum via the corticopontocerebellar pathway. Although it is well documented on cerebral single photon emission tomography (SPECT) in patients with epilepsy, it is rarely observed in seizures originating from brain tumours. We report a 41-y-old man who whilst undergoing ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for investigation of suspected glioma, developed a generalized seizure. The scan performed shortly after seizure onset demonstrated intense metabolic activity in the right superior frontal lobe and in the contralateral cerebellar hemisphere consistent with CCH.     

A case of theophylline-associated seizures with postictal fever and postictal pleocytosis

We report a 70-year-old man who developed theophylline-associated seizure with postictal fever and postictal pleocytosis. He was admitted to our hospital for a left hemiconvulsion lasting for two hours. The concentration of theophylline was high (21.6ng/ml), and electroencephalogram demonstrated periodic lateralized epileptiform discharges. Diffusion-weighted magnetic resonance imaging showed high signal intensity lesions in the right cingulated gyrus, insula and thalamus. Temperature above 38.0° was detected 5.5 hours after seizure and lasted for 60 hours. Cerebrospinal fluid (CSF) analysis on day 2 demonstrated pleocytosis (62/uL) with a predominance of polymorphonuclear leukocytes (90%). Temperature and CSF pleocytosis subsided after sedation. Intracranial inflammatory or infectious disease is the first consideration in epilepsy with fever and CSF pleocytosis, and then diagnosis of postictal fever and postictal pleocytosis should be made only by rigorous exclusion of that possibility.     

Bilateral occipital lobe hyperperfusion demonstrated by single photon emission computed tomography during seizure-related cortical blindness.

An 81-year-old woman with chronic dementia developed lethargy, confusion, binocular blindness, and episodic left-beating nystagmus. Diffusion magnetic resonance imaging (MRI) revealed high signal in the right occipital region suggesting recent ischemia. A concurrent electroencephalogram (EEG) showed a right occipital seizure focus that spread to the opposite occipital lobe. A single photon emission computed tomography (SPECT) performed during the seizure epoch showed bilateral occipital lobe hyperperfusion. This is the second report to document SPECT bi-occipital hyperperfusion in seizure-related cortical blindness.     

Prolonged postictal encephalopathy

Eleven patients (6 males, 5 females; ages 7.5 to 40 years, mean 27.8) had prolonged postictal confusion lasting from 4 to 10 days. During that time, the EEG showed a typical encephalopathic pattern. Comprehensive evaluation ruled out the possibility of metabolic, toxic, drug-related, or ongoing nonconvulsive status epilepticus. We have designated this syndrome as prolonged postictal encephalopathy (PPIE). Nine of 11 patients were mildly to borderline mentally retarded. Ten had previous episodes of status epilepticus. Nine of 11 had minimal structural abnormalities (mainly diffuse cortical atrophy). Nine patients had multiple recurrent episodes of PPIE. All episodes occurred following a cluster of seizures: in 8 patients after a cluster of generalized tonic-clonic seizures, in 2 after complex partial seizures, and in 1 patient after a cluster of atypical absence seizures. This series suggests that vulnerability to develop PPIE exists in patients with diffuse structural abnormalities, mild to borderline mental retardation, a history of status epilepticus, and a tendency of seizures to cluster.     

Subacute postictal aggression in patients with epilepsy

Three men with epilepsy (age range, 38-62) who exhibited brief episodes of violent behavior during the postictal period are described. Disease duration ranged from 27 to 44 years. Patients had both complex partial seizures and secondarily generalized tonic-clonic seizures, which were refractory to antiepileptic drugs. Postictal aggression occurred shortly after a seizure and lasted 5-30 minutes. The patients displayed physically and verbally aggressive behavior toward others, but regained consciousness promptly and showed regret afterward. Interictal EEGs revealed temporal spikes, SPECT showed hypoperfusion in the temporal and frontal areas in two patients, and neuropsychological examination revealed poor frontal lobe function in two patients. Characteristics of our cases are consistent with subacute postictal aggression (SPA) reported previously. Epilepsy of prolonged duration and brain dysfunction involving a broad area including the temporal and frontal lobes may be associated with the occurrence of subacute postictal aggression.     

The postictal electroencephalogram

Postictal phenomena, their laterality and duration, were studied among 51 patients with scalp EEG-recorded seizures whose origin, evolution and postictal phase were clearly depicted. Regional delta was the most common postictal change (PIC), appearing in 29 patients (57%). Regional attenuation occurred in 15 cases (29%) while the EEG reverted immediately to its interictal nature in 16 instances (31%). 'Activation' of spikes postictally occurred after 13 of the 51 seizures (25%), always over the lobe of seizure onset. PIC, whatever its nature, appeared principally or exclusively ipsilateral to seizure origin in all 35 patients. Moreover, when such changes were bilaterally distributed, they persisted longer on the side of seizure origin in all but one case when durations were bilaterally equal. A multiple PIC (greater than 1 phenomenon) occurred after 21 seizures (41%) while a single change appeared after 14 attacks (27%). Multiple changes occurred more commonly when the seizures had evolved to independent bilateral seizures or to grand mal (77%) than when they were confined to the hemisphere of origin (14%). Thus multiple changes were more often distributed bilaterally (90%) than were single changes (29%). Conversely, seizures without any propagation (focal only) were those most likely to show no postictal change. Multiple changes lasted longer (mean 406 sec) than single changes (79 sec), but duration of PIC was unaffected by seizure propagation or its nature, except for grand mal. Seizure duration had no effect on PIC duration except for grand mal attacks whose postictal effects were predictably longer.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hypersensitivity of cortical muscarinic receptors in Parkinson's disease demonstrated by PET

The status of muscarinic receptors (mAChRs) is not clear in Parkinson's disease (PD). We measured mAChR binding in the brain of eight patients with PD and eight, age-matched, healthy controls by positron emission tomography (PET) and [¹¹ C]N-methyl-4-piperidyl benzilate ([¹¹ C]NMPB). PD patients were not demented according to DSM III criteria but showed significant frontal lobe dysfunction in the Modified Wisconsin Card Sorting Test. A mean K₃ value, which is an index of mAChR binding calculated by a graphical method, was 20% higher in the frontal cortex of PD patients than controls (p<0.05). Hypersensitivity of mAChRs in the frontal cortex of PD patients may be a response to a loss of ascending cholinergic input to that region, and may relate to frontal lobe dysfunction in PD.     

Cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy is characterised by ipsilateral headache, hypertension, seizures, and focal neurological deficits. If not treated properly it can result in severe brain oedema, intracerebral or subarachnoid haemorrhage, and death. Knowledge of CHS among physicians is limited. Most studies report incidences of CHS of 0-3% after carotid endarterectomy. CHS is most common in patients with increases of more than 100% in perfusion compared with baseline after carotid endarterectomy and is rare in patients with increases in perfusion less than 100% compared with baseline. The most important risk factors in CHS are diminished cerebrovascular reserve, postoperative hypertension, and hyperperfusion lasting more than several hours after carotid endarterectomy. Impaired autoregulation as a result of endothelial dysfunction mediated by generation of free oxygen radicals is implicated in the pathogenesis of CHS. Treatment strategies are directed towards regulation of blood pressure and limitation of rises in cerebral perfusion. Complete recovery happens in mild cases, but disability and death can occur in more severe cases. More information about CHS and early institution of adequate treatment are of paramount importance in order to prevent these potentially severe complications.     

Central action of benserazide after COMT inhibition demonstrated in vivo by PET

Summary Positron emission tomography (PET) following intravenous administration of -[¹¹ C]-L-DOPA provides a method of assessing regional cerebral uptake and utilization of levodopa. Cerebral levodopa kinetics in the rhesus monkey were investigated after the inhibition of catechol-O-methyltransferase (COMT) with RO 40-7592, and after coadministration of the peripheral aromatic L-amino acid decarboxylase (AADC) inhibitors benserazide and carbidopa. Pretreatment with RO 40-7592 (10 mg/kg), benserazide (10 mg/kg) or carbidopa (3.5 mg/kg) did not change striatal k₃, which mainly reflects the ability for the brain tissue to convert [¹¹C]-L-DOPA to [¹¹C]-dopamine, although the brain's uptake of radioactivity increased substantially after pretreatment with the AADC inhibitors. When benserazide was coadministered with RO 40-7592 (10 mg/kg) a dose-dependent decrease in striatal k₃ was measured with an apparent ED₅₀ of 3 mg/kg. No such effect was indicated after pretreatment with the combination of RO 40-7592 (10 mg/kg) and carbidopa (3.5 mg/kg). The possible negative interactions of coadministration with COMT inhibitors and predominantly peripherally acting AADC inhibitors must be considered when used in the therapy of Parkinson's disease.A contribution from the Uppsala University PET centre     

Paroxysmal arousal in epilepsy associated with cingulate hyperperfusion

A patient with nocturnal frontal lobe epilepsy characterized by paroxysmal motor attacks during sleep had brief paroxysmal arousals (PAs), complex episodes of nocturnal paroxysmal dystonia, and epileptic nocturnal wandering since childhood. Ictal SPECT during an episode of PA demonstrated increased blood flow in the right anterior cingulate gyrus and cerebellar cortex with hypoperfusion in the right temporal and frontal associative cortices.     

A case of atypical type of Sturge-Weber syndrome demonstrated reversible change by MRI FLAIR method in ictus and in postictal state]

We report a patient of atypical type of Sturge-Weber syndrome who demonstrated a reversible change by MRI FLAIR method in ictus and postictal state. A 5-year-old boy was admitted to our hospital because of severe headache, vomiting and loss of consciousness with his eyes conjugated to left for a few minutes. He had no facial nevus and other abnormal findings in physical examination. CT scan showed two small calcifications in the right occipital lobe. Postcontrast T 1-weighted image of MRI demonstrated a right parieto-occipital leptomeningeal enhancement. We diagnosed this case as an atypical type of Sturge-Weber syndrome. Although, on admission, FLAIR method showed the area of high signal intensity, after anticonvulsant therapy, those abnormal area disappeared. It is presumably detected by FLAIR method slight extravasation of plasma element in the surface of the brain due to regional hyperperfusion in ictus.     

Duration of postictal psychotic episodes

PURPOSE: To clarify duration of postictal psychosis (PIP) episodes and identify factors that influence its duration. METHODS: Fifty-eight patients with epilepsy exhibited 151 PIP episodes during a mean follow-up period of 12.8 years. Distribution of the duration of these episodes was determined, and factors potentially affecting were analyzed. Factors analyzed included PIP-related variables (i.e., antecedent seizures and the lucid interval) and patient characteristics (i.e., type of epilepsy, lateralization of EEG abnormalities, and intellectual functioning). RESULTS: The mean duration of the 58 first PIP episodes was 10.5 days, and that of all 151 PIP episodes (including multiple episodes) was 9.2 days. Approximately 95% of the PIP episodes resolved within 1 month. Most PIP-related variables, except for antipsychotic drugs administered, were not associated with duration of the episodes. Several patient characteristics, i.e., history of interictal psychosis, family history of psychosis, and intellectual functioning, were associated with duration of the PIP episodes. CONCLUSIONS: This study showed that most PIP episodes last less than 1 month. PIP episodes appear to be prolonged when individuals have an underlying vulnerability to psychosis. Clinical phenomena that can trigger PIP may not determine the course of the PIP episode.     

Electroclinical analysis of postictal noserubbing

BACKGROUND: Postictal noserubbing (PIN) has been identified as a good, albeit imperfect, lateralizing and localizing sign in human partial epilepsy, possibly related to ictal autonomic activation. METHODS: PIN was studied prospectively in a group of consecutive patients admitted for video-EEG monitoring, with the laterality of noserubbing correlated with electrographic sites of seizure onset, intra- and interhemispheric spread, and sites of seizure termination. RESULTS: PIN was significantly more frequent in temporal than extratemporal epilepsy (p<0.001; 23/41 (56%) patients and 41/197 (21%) seizures in temporal lobe epilepsy compared with 4/34 (12%) patients and 12/167 (7%) seizures in extratemporal epilepsy). The hand used to rub the nose was ipsilateral to the side of seizure onset in 83% of both temporal and extratemporal seizures. Seizures with contralateral PIN correlated with spread to the contralateral temporal lobe on scalp EEG (p<0.04). All extratemporal seizures with PIN showed spread to temporal lobe structures. One patient investigated with intracranial electrodes showed PIN only when ictal activity spread to involve the amygdala: seizures confined to the hippocampus were not associated with PIN. PIN was not observed in 63 nonepileptic events in 17 patients. Unexpectedly, one patient with primary generalized epilepsy showed typical PIN after 1/3 recorded absence seizures. CONCLUSIONS: This study confirms PIN as a good indicator of ipsilateral temporal lobe seizure onset. Instances of false lateralization and localization appear to reflect seizure spread to contralateral or ipsilateral temporal lobe structures, respectively. Involvement of the amygdala appears to be of prime importance for induction of PIN.     

Self-reported characteristics of postictal headaches

We explored the characteristics of postictal headaches (PIH) by telephone survey of 372 patients attending an epilepsy clinic. Overall, 45% experienced PIH and 21% had PIH after every seizure: Of this group, 39% described their headaches as severe. In contrast, 10% of patients with occasional PIH described the headaches as severe. Patients with four or fewer seizures a year were more than twice as likely to have PIH after every seizure than were those with more frequent seizures (p = 0.003). Seventy-three percent of patients with PIH did not have headaches other than seizure-associated headaches. Healthcare providers should consider PIH in assessing the effect of seizures on quality of life (QOL) of patients with epilepsy.     

Impact of periictal interventions on respiratory dysfunction,postictal EEG suppression,and postictal immobility

Purpose: Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy‐related mortality. Seizure‐related respiratory dysfunction (RD), the duration of postictal generalized electroencephalography (EEG) suppression (PGES), and duration of postictal immobility (PI) may be important in the pathophysiology of SUDEP. Periictal interventions may reduce the risk of SUDEP. Methods: We assessed the impact of periictal nursing interventions on RD, PGES, and PI duration in patients with localization‐related epilepsy and secondarily generalized convulsions (GCs) recorded during video‐EEG telemetry in the epilepsy monitoring unit. Video‐EEG data were retrospectively reviewed. Interventions including administration of supplemental oxygen, oropharyngeal suction, and patient repositioning were evaluated. Interventions were performed based on nursing clinical judgment at the bedside and were not randomized. The two‐sided Wilcoxon rank‐sum test was used to compare GCs with and those without intervention. Robust simple linear regression was used to assess the association between timing of intervention and duration of hypoxemia (SaO₂ < 90%), PGES, and PI using data from only the first GC for each patient. Key Findings: Data from 39 patients with 105 GCs were analyzed. PGES >2 s occurred following 31 GCs in 16 patients. There were 21 GCs with no intervention (NOINT) and 84 GC with interventions (INT). In the INT group, the duration of hypoxemia was shorter (p = 0.0014) when intervention occurred before hypoxemia onset (mean duration 53.1 s) than when intervention was delayed (mean duration 132.42 s). Linear regression indicated that in GCs with nursing interventions, earlier intervention was associated with shorter duration of hypoxemia (p < 0.0001) and shorter duration of PGES (p = 0.0012). Seizure duration (p < 0.0001) and convulsion duration (p = 0.0457) were shorter with earlier intervention. PI duration was longer for GCs with PGES than GCs without PGES (p < 0.0001). The mean delay to first active nonrespiratory movement following GCs with PGES was 251.96 s and for GC without PGES was 66.06 s. The duration of PI was positively associated with lower SaO₂ nadir (p = 0.003) and longer duration of oxygen desaturation (p = 0.0026). There was no association between PI duration and seizure duration (p = 0.773), between PI duration and PGES duration (p = 0.758), or between PI duration and the timing of first intervention relative to seizure onset (p = 0.823). PGES did not occur in the NOINT group. The mean duration of desaturation was longer (110.9 vs. 49.9 s) (p < 0.0001), mean SaO₂ nadir was lower (72.8% vs. 79.7%) (p = 0.0086), and mean end‐tidal CO₂ was higher (58.6 vs. 50.3 mmHg) (p = 0.0359) in the INT group compared with the NOINT group. The duration of the seizure or of the convulsive component was not significantly different between the INT and NOINT groups. Significance: Early periictal nursing intervention was associated with reduced duration of RD and reduced duration of PGES. These findings suggest the possibility that such interventions may be effective in reducing the risk of SUDEP in the outpatient setting. Validation of these preliminary data with a prospective study is needed before definitive conclusions can be reached regarding the efficacy of periictal interventions in reducing the risk of SUDEP.     

Late postictal residual perfusion abnormality in epileptogenic zone found on 6-hour postictal SPECT

BACKGROUND: Temporal evolution of regional hyperperfusion in the late postictal stage in epilepsy has not been clearly defined. OBJECTIVE: To establish the late temporal evolution of the perfusion in epileptogenic zones using 6-hour postictal SPECT. METHODS: Ictal 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) SPECT was performed in 10 patients with intractable epilepsy (4 temporal lobe epilepsy, 6 neocortical epilepsy) followed by delayed acquisition and another 6-hour postictal SPECT after reinjection of 99mTc-HMPAO. The delayed acquired SPECT was subtracted from the reinjection SPECT to yield the 6-hour postictal SPECT. Interictal SPECT was acquired on another day. Late postictal perfusion was examined visually, and asymmetric indexes were compared with each other on ictal, 6-hour postictal, and interictal SPECT. RESULTS: Ictal SPECT images of delayed acquisition were visually and quantitatively similar to those of early acquisition. In 7 of 10 patients, 6-hour postictal SPECT showed hyperperfusion. In one patient, the 6-hour postictal SPECT image showed less perfusion than the interictal SPECT image in the epileptogenic zone. CONCLUSIONS: Late postictal hyperperfusion was found in more than half of the patients. Postictal perfusion abnormalities did not come back to the interictal phase 6 hours after ictus and these were identified on ictal/postictal 99mTc- HMPAO SPECT.