Cerebral Hyperperfusion and Delayed Coma Recovery after Subdural Hematoma Evacuation

Acute subdural hematoma is a devastating neurological injury with significant morbidity and mortality. In patients with large subdural hematoma resulting in compression of the underlying brain and lateral brain shift, severe neurological deficits and coma can occur. Emergent neurosurgical decompression is a life-saving intervention which improves mortality and neurological function. Persistent coma despite subdural hematoma evacuation is often the result of persistent midline shift, cerebral infarctions related to initial elevated intracranial pressure and herniation, nonconvulsive seizures, and other metabolic and infectious causes; however, a subset of patients remains comatose without a discernable etiology. In this report, we describe an elderly patient who remained comatose without a known cause for several weeks after subdural hematoma evacuation and was found to have delayed cerebral hyperperfusion on brain imaging. After several days, there was marked recovery of consciousness which occurred in a timeframe that matched improvement in brain imaging findings. Cerebral hyperperfusion following subdural hematoma evacuation requires further investigation, and should be considered as a cause of persistent but potentially recoverable coma.     

Ipsilateral independent periodic lateralized epileptiform discharges

We have identified a previously unreported subtype of periodic lateralized epileptiform discharge (PLED) characterized by periodic discharges arising from ipsilateral independent foci. All 4 patients had acute cerebral lesions, and 3 of them had focal motor seizures with secondary generalization. The site of localization of the PLEDs corresponded to the boundaries of the underlying structural lesion or lesions, and this, together with the variable temporal relationship between them, supports a cortical origin for PLEDs associated with underlying lesions. The spatial and temporal independence of these periodic discharges in combination with their association with (1) acute cerebral lesions, (2) altered consciousness and seizures, and (3) resolution with time leads us to propose the term “IpsiIPs” to describe this subtype of PLEDs.     

Acute subdural hematoma and the periodic lateralized epileptiform discharges.

Focal motor seizures associated with periodic lateralized epileptiform discharges (PLEDs) were observed in two patients with acute subudral hematoma. Following the surgery, one patient continued to exhibit PLEDs but clinical seizures were absent PLEDs recurred in the second patient due to inadequate anticonvulsant medication. Autopsy study in one patient suggests that underlying cerebral contusion was not responsible for the occurrence of PLEDs.     

EEG findings after a cerebral territorial infarct in patients who develop early- and late-onset seizures

BACKGROUND: EEG findings are generally not considered to be very helpful for the diagnosis of poststroke seizures. PURPOSE: This retrospective study investigates the EEG characteristics in patients who develop seizures after a cerebral territorial infarct. PATIENTS AND METHODS: The study population consisted of 110 patients with seizures after a cerebral territorial infarct (12 with early- and 98 with late-onset seizures) and 275 without. All 110 patients had an interictal EEG after their first seizure. The EEG patterns after the stroke were compared between those available from 69 patients who developed seizures and those from 275 who did not. Also the EEG patterns after the seizure (n = 110) were compared to those in the poststroke group without subsequent seizures. RESULTS: Periodic lateralized epileptic discharges (PLEDs) on the EEG after stroke were only found in 5.8% of the patients with early- and late-onset seizures. They were absent in the stroke group without seizures. Frontal intermittent rhythmic delta activities (FIRDAs) were observed in 24.6% of the seizure group, compared to 1.1% in the control group. Diffuse slowing occurred also significantly more often in the former (21.7%) compared to the latter group (5.1%). Normal EEG findings were seen in 53.8% of the stroke patients without seizures, compared to 8.5% in those with seizures. The incidence of focal slowing was the same in both groups. Similar findings were observed when comparing the EEG patterns of the patients after the first poststroke seizure to those of the stroke group without subsequent seizures. In patients with early-onset seizures, PLEDs or FIRDAs were present in 25% each. FIRDAs and diffuse slowing were significantly more frequently observed on the poststroke EEGs of patients who developed late-onset seizures. CONCLUSIONS: FIRDAs, PLEDs and diffuse slowing are the most frequent EEG findings in patients with early-onset seizures. Patients with FIRDAs and diffuse slowing on the poststroke EEG have a high risk to develop late-onset seizures, while the chance is reduced in those with normal EEG findings.     

Mild hypothermia for hemispheric cerebral infarction after evacuation of an acute subdural hematoma in an infant

The use of mild hypothermia to treat hemispheric infarction after evacuation of an acute subdural hematoma in an infant is reported. The patient, a 2-year-old boy, presented with a deteriorating level of consciousness after a fall from a tree. Computed tomography (CT) scan revealed an acute subdural hematoma on the right side with marked midline shift, and emergency evacuation of the hematoma was performed. The postoperative course was uneventful until the patient's intracranial pressure (ICP) rose and his condition deteriorated 3 days after surgery. CT scan revealed a hemispheric infarction on the injured side. Mild hypothermia was induced to control the ICP and protect the brain. While the hypothermia was effective in lowering the elevated ICP, it failed to arrest progression of the infarction. The patient was discharged with mild disability 2 months after the injury. No serious complications occurred during or after the hypothermia. Our experience indicates that hypothermia can be a useful procedure for controlling the ICP in children with severe traumatic brain injury including acute subdural hematoma, although its capability to protect the brain from severe, progressive ischemia appears to be limited.     

Periodic lateralized epileptiform discharges: etiology, clinical aspects, seizures, and evolution in 130 patients.

The purpose of this study was to analyze the clinical aspects in 130 patients presenting periodic lateralized epileptiform discharges (PLEDs) in their EEG and to compare these results with those found in the literature. Etiology, neurologic deficit, seizure occurrence, and evolution were studied in each patient by historical review. The recordings were obtained on 8- or 16-channel EEGs with electrode placement according to the International 10-20 System. Recordings containing PLEDs were selected. PLEDs were defined as repetitive periodic, focal, or hemispheric epileptiform discharges (spikes, spike and waves, polyspikes, sharp waves) usually recurring every 1 to 2 seconds. The statistical study was carried out via the chi(2) test using the computer program SPSS. The main etiology found in this group of patients was stroke (61 of 130 patients). Other processes found were brain infections, tumors, hematomas, and several other entities grouped together as miscellaneous (anoxic encephalopathy, subarachnoid hemorrhage, craniocerebral trauma, Creutzfeldt-Jacob disease, migraine, multiple sclerosis, and aminophylline intoxication). Half of these patients (65 of 130) developed seizures, mostly partial motor seizures. No significant relation between etiology and seizures was found (chi(2) = 2.81, P = 0.4222). Seizures recurred in 14 of 130 patients during a follow-up of 14.5 months. PLEDs were not recorded in any EEG at the time of seizure recurrence. PLEDs constitute a distinctive but uncommon EEG phenomenon of repetitive, periodic, and stereotyped lateralized complexes. In agreement with the literature, PLEDs were associated with an acute process and occurred early during the course of the illness in all patients studied and were usually associated with structural lesions, with stroke being the main etiology. Traditionally, seizures occur with PLEDs but it is also accepted that they can exist in patients who never develop epileptic activity, either clinically or electrically, as demonstrated in 50% of the patients studied. No significant association between seizures and any etiology could be found. It was not demonstrated that the occurrence of seizures may influence the outcome in any way.     

Benign bilateral independent periodic lateralized epileptiform discharges

Bilateral independent periodic lateralized epileptiform discharges (BIPLEDs) usually appear transiently in patients with severe disturbances of consciousness and are indicative of a poor prognosis. Recurrent BIPLEDs have not previously been reported in the literature. We report a 64-year-old patient with bilateral hippocampal lesions (cerebral infarction) who exhibited persistent periodic lateralized epileptiform discharges (PLEDs) (chronic PLEDs) associated with recurrent BIPLEDs. Electroencephalography was recorded for more than 6 months. Left hemispheric PLEDs appeared first. Next, PLEDs shifted to the right hemisphere and BIPLEDs occasionally developed. Brain magnetic resonance imaging and single-photon emission computed tomography with technetium-99-hexamethyl-propyleneamine oxime was performed before and after the appearance of BIPLEDs. The patient had no remarkable clinical symptoms aside from mild memory impairment for this period of time. This is the first case of recurrent 'benign' BIPLEDs, that is, BIPLEDs with a positive prognosis.     

Periodic lateralized epileptiform discharges: association with seizures.

The clinical features and EEGs of 45 consecutive patients (40 adults and 5 children) who had periodic lateralized epileptiform discharges (PLEDs) were reviewed to determine the relationship between seizures and PLEDs. Focal encephalitis and ischemic stroke were the most frequent underlying processes for adult patients. All of the children, but only six of the adults, had long-lasting cerebral disorders whereas the remaining adults had acute or subacute illness. There were 38 patients (84.4%) experiencing a seizure disorder. Twenty-six of them had their first seizure during their acute illness, as the pattern of PLED was encountered. Eight cases had status epilepticus, and seven of them had epilepsia partialis continua. Nineteen patients had a recent seizure in the day when PLEDs were observed but not during EEG recording; 12 patients had their seizures within 10 days before the observation of PLED. PLEDs were grouped into three categories with respect to their extensions: lateralized to one hemisphere (n = 22), localized in one region (n = 17) and being prominent over one side with contralateral spread (n = 6). The last group was found to be more closely associated with frequent seizures or status epilepticus than the other two groups. Our results showed that PLEDs were highly correlated with recent seizures in the majority of the patients. These EEG findings may be considered as a manifestation of an increased neuronal excitability caused by different etiologies; but not an ictal pattern.     

Retrospective inventory of EEG abnormalities in partial status epilepticus.

In this retrospective study, EEG activity in partial status epilepticus (PSE) was classified into different patterns from analysis of both ictal and interictal discharges. In 64 patients with recorded PSE, continuous seizures and closely spaced seizures interrupted by only brief flat periods were uncommon. PLEDs, defined as classic periodic lateralized epileptiform discharges, and PLEDs Plus, defined as PLEDs associated with stereotyped low amplitude, were the most common abnormalities. PLEDs and PLEDs Plus can each occur alone or sequentially (sequential PLEDs) between consecutive seizures. The quantity of ictal activity was significantly lower with PLEDs, sporadic spikes and with the absence of epileptiform abnormalities than with PLEDs Plus and sequential PLEDs. EEG monitoring is important to gauge the effectiveness of treatment, particularly in patients with patterns associated with a high incidence of seizure activity, namely continuous seizures with or without flat periods, sequential PLEDs and PLEDs Plus. From serial recordings, a sequence was reconstructed which may be relied upon to further assess the need for additional energetic therapeutic measures. The reconstructed sequence differed in patients with chronic lesions since sequential PLEDs and PLEDs Plus were identified exclusively in patients with acute or subacute lesions.     

SPECT in periodic lateralized epileptiform discharges (PLEDs): a form of partial status epilepticus?

Periodic lateralized epileptiform discharges (PLEDs) are a well defined electroencephalographic entity but whether PLEDs represent an ictal condition or not remains debated. Much work has been done using electroencephalography (EEG) but new approaches using cerebral perfusion imaging may give more information about this question. We aimed to evaluate if PLEDs were associated with high regional cerebral blood flow (rCBF). We studied 18 patients with PLEDs and different pathologies, and performed brain single-photon-emission computed tomography (SPECT) during and, for three cases, after the disappearance of PLEDs. Qualitative variations and locations of rCBF were compared with PLEDs. Association with seizures and type of seizures were also assessed. SPECT showed high rCBF in 18/18 patients (100%). The location of PLEDs and high rCBF matched in 17/18 cases (94%). In the three cases where SPECT was performed after PLEDs disappeared, the high rCBF had cleared (100%). Eighteen cases (100%) presented seizures before recording of PLEDs, mainly motor (partial motor or generalized tonic-clonic). Where there was a decreased rCBF (related to a lesion) there was little relationship to PLEDs and all patients with decreased rCBF had an adjacent increased rCBF. These results confirm preliminary case reports. Hyperperfusion adds further to the argument that PLEDs may be related to a form of partial status epilepticus.     

EEG periodic lateralized activities associated with ischemic cerebro-vascular strokes: physiopathologic significance and localizing value]

Eleven cases of periodic lateralized epileptiform discharges (PLED) with stroke (9 cases) or transient ischemic attacks are reported. PLEDs are often associated with depression of conscience (81%) or partial pure motor epileptic seizures (90%). PLEDs and seizures seem independent on EEG. Ischemic strokes associated with PLEDs have some characteristic features: old age, vascular risk factors, parieto-occipital areas infarcts and frequent association with TIAs. PLEDs seem to be often associated with watershed infarcts. The relations between PLEDs and cerebral ischemia are discussed.     

Isolated oculomotor palsy. An unusual presentation of chronic subural hematoma

Isolated oculomotor palsy is an unusual symptom in chronic subdural hematomas and it is very rare as initial manifestation. We report a patient with a chronic subdural hematoma that presented with a complete third nerve palsy and normal consciousness. Complete recovery was achieved after surgical evacuation. Rebleeding within the hematoma cavity, most possibly favored by antiaggregating agents, was considered responsible for this rare presentation. In these cases expeditious surgical evacuation is indicated.     

Chronic periodic lateralized epileptiform discharges

Six patients with chronic epilepsy had persistent periodic lateralized epileptiform discharges (PLEDs) in their interictal electroencephalographic recordings. Three patients had complex partial seizures, two had infantile spasms, and one had multifocal seizures. Four patients had cerebral pathologic changes consisting of tuberous sclerosis (two patients), a porencephalic cyst (one patient), and a chronic brain abscess (one patient). Although PLEDs are usually seen in association with an acute or subacute disturbance of cerebral function, the findings in this group of patients show that chronic PLEDs also can occur in patients with long-standing seizure disorders or chronic brain lesions.     

Subdural tension pneumocephalus after trephination for chronic subdural hematoma

Symptomatic tension pneumocephalus developed after an evacuation of chronic subdural hematoma is reported. In this 71 year-old man, a rapid deterioration of consciousness was noted 5 days after a trephination for bilateral chronic subdural hematomas. An evacuation of hematoma was performed under a local anesthesia, and the preoperative and immediate postoperative course was uneventful. Subdural tension pneumocephalus was confirmed by typical CT findings and treated by re-trephination and drainage. The literature on the tension subdural pneumocephalus was reviewed, and the mechanism of its development was briefly discussed.     

Ictal sensory periodic lateralized epileptiform discharges

We describe the case of a 74-year-old man with left parietal arteriovenous malformation (AVM) and cerebral white matter radiation necrosis who developed persistent subjective right-sided groin pulsations. The EEG revealed left parietal periodic lateralized epileptiform discharges (PLEDs) time-locked to these sensations, confirming that the patient's symptoms represented sensory seizures with ictal PLEDs as the electrographic correlate. To our knowledge, this is the first reported case of ictal PLEDs manifesting as sensory seizures.     

PLED pattern and its clinical significance in stroke patients

The pathophysiological connection between periodic lateralized epileptiform discharges (PLED) and epileptic seizures is still not clear. In the study clinical data and EEG findings were analysed in 22 patients aged 43-90 years with a history of stroke in whom EEG disclosed PLED. Eleven patients were studied in the acute phase of stroke and 11 were studied years after stroke when the diagnosis was established of poststroke epilepsy. In 2 patients in acute stroke group single epileptic seizures occurred and 5 had partial status epilepticus. In the group with poststroke epilepsy 4 had single seizures and 4 had epileptic status with partial epilepsy seizures. Thus, in 15 out of 22 patients PLEDs were noted after epileptic seizures. In all cases PLED appearance was connected with consciousness disturbances, lasting 1 to 17 days. In 6 cases PLED pattern was interrupted by seizure activity over one hemisphere, in 3 of them partial epileptic seizures were associated with it. In acute phase of stroke neuroimaging demonstrated the presence of fresh ischaemic foci, but in cases of poststroke epilepsy no such fresh foci were observed. These results suggest that PLED frequently can be associated with epilepsy, and in some patients it can be a bioelectrical manifestation of partial status epileptic.     

The risks of epilepsy after traumatic brain injury.

The aim of this study is to present the incidence of traumatic brain injury (TBI) and identify those characteristics of brain injuries that are associated with the development of seizures. We identified 5984 episodes of TBI (loss of consciousness, post-traumatic amnesia, or skull fracture) in Olmsted County, Minnesota, from 1935 to 1984. Of these, 4541 were followed for seizure. Injuries were classified as mild (loss of consciousness or amnesia less than 30 minutes), moderate (loss of consciousness 30 minutes to 1 day or a skull fracture), or severe (loss of consciousness of more than 1 day, subdural hematoma, or brain contusion). The incidence of TBI in the period from 1975 to 84 peaked at 800 per 100 000 in males aged 15-24. The relative risk of seizures was 1.5 (95 percent confidence interval 1.0-2.2) after mild injuries, but with no increase after 5 years; 2.9 (95 percent confidence interval 1.9-4.1) after moderate injuries; and 17.2 (95 percent confidence interval 12.3-23.6) after severe injuries. Significant risk factors were brain contusion with subdural hematoma, skull fracture, loss of consciousness or amnesia of 1 day or more, and age over 65 years. We conclude that TBI is a major public health problem and contributes to the occurrence of seizures and epilepsy.     

Spontaneously Rapid Resolution of Acute Subdural Hemorrhage with Severe Midline Shift

Acute subdural hematoma is usually a neurological emergency that requires hematoma evacuation or close observation. However, spontaneous resolutions of an acute subdural hematoma without surgical interventions have been reported rarely. We report on a case who showed rapid resolution of an acute subdural hematoma with neurological improvement and review the relevant literatures.     

Incidence of recurrent seizures following hospital discharge in patients with LPDs (PLEDs) and nonconvulsive seizures recorded on continuous EEG in the critical care setting

PurposeContinuous EEG (cEEG) has helped to identify nonconvulsive seizures (NCS) and nonconvulsive status epilepticus (NCSE) along with lateralized periodic patterns (LPDs or PLEDs) in ICU patients with much higher frequency than previously appreciated, but understanding their implications may be more complex. The aim of this study was to investigate the incidence of recurrent seizures after hospital discharge and their associated factors in patients with PLEDs and NCS in the critical care setting.MethodsAfter IRB approval, we used our EEG reporting database to find 200 consecutive patients who had PLEDs and/or NCSs on cEEG. Patients with less than 3 months of follow-up were excluded. Remaining patients were divided into three groups: PLEDs + Seizure (NCS/NCSE), PLEDs only, and Seizures (NCS/NCSE) only. Medical records were reviewed to gather demographical and clinical details. Univariate data analysis was done using JMP 9.0 (Marlow, Buckinghamshire, UK).ResultsThere were 51 patients in ‘PLEDs + Seizure’ group, 45 in ‘PLEDs only’ group, and 22 in ‘Seizure only’ group. Ischemic stroke, hemorrhage, and tumors were the top three etiologies. Nearly 47% of our study population had postdischarge seizures during a mean follow-up period of 11.9 (+/− 6) months. We found that 24.4% of patients in the PLEDs only group had seizures after discharge, which increased to 60.7% if they had seizures as well during their ICU stay. Slightly more than 52% of patients had a postdischarge EEG, of which, 59% was in the form of inpatient cEEG during a rehospitalization, accounting for 30.5% of the total study population. It was an indicator of high readmission rates in this population.ConclusionAlmost every other patient with PLEDs and/or NCS on cEEG had seizures after ICU discharge. A quarter of patients on cEEG in the ICU with PLEDs alone had seizures after discharge, and after excluding prior epilepsy, 17% of patients with PLEDs had seizures on follow-up. This was dramatically increased with the recording of PLEDs with NCS, with 60% of patients having seizures after discharge from the ICU and 48% of patients after excluding prior epilepsy. Patients with NCS on cEEG alone had 63% chance of seizure recurrence that dropped to 38% with exclusion of prior epilepsy. Future studies are needed to define the postdischarge outcomes including seizure recurrence in this patient population.This article is part of a Special Issue entitled “Status Epilepticus”.     

Significance of Epileptiform Discharges in Patients without Epilepsy in the Community

PURPOSE: To determine the frequency of recording epileptiform discharges (EDs) in patients without epilepsy in the community and to assess their risk of seizure disorders subsequently developing. METHODS: We identified all outpatient and inpatient EEGs that were recorded in persons residing in Rochester, Minnesota, from 1979 to 1988. Patients with a history of unprovoked seizure disorders before the index EEG were excluded. Periodic lateralized EDs (PLEDs) were not evaluated, because of their well-established association with seizure disorders. RESULTS: Five hundred twenty-one patients in the community had no history of unprovoked seizure disorders before their EEG. Sixty-four (12.3%) patients had EDs; neither isolated unprovoked seizure nor epilepsy developed during 230.8 person-years of follow-up. Forty-seven (73.4%) of the 64 patients had acute or progressive cerebral disorders when EEG detected EDs. Seizures that were acutely provoked by the underlying disorder (enlarging brain tumor, cerebral infarct, or bilateral subdural hematoma, in one patient each) subsequently developed in three (6.3%) of the 64 patients. Seizures of any type did not develop in the 17 patients without acute or progressive cerebral disorders. CONCLUSIONS: In a community setting, EDs are sometimes observed in patients without epilepsy. However, nearly three fourths have underlying acute or progressive cerebral disorders. Acutely provoked seizures may develop in a small proportion of patients. Although none of our patients developed isolated unprovoked seizures or epilepsy, a longer period of follow-up is needed to determine their risks relative to the general population.