Brain SPECT imaging in temporal lobe epilepsy

Epilepsy, mental health disorder, or both?

Temporal lobe epilepsy (TLE), a subset of the seizure disorder family, represents a complex neuropsychiatric illness, where the neurological presentation may be complemented by varying severity of affective, behavioral, psychotic, or personality abnormalities, which, in turn, may not only lead to misdiagnosis, but also affect the management. This paper outlines a spectrum of mental health presentations, including psychosis, mood, anxiety, panic, and dissociative states, associated with epilepsy that make the correct diagnosis a challenge.

Neuroimaging of epilepsy: therapeutic implications

Neuroimaging has important applications in the diagnosis and treatment of patients with seizures and epilepsy. Having replaced computed tomography (CT) in many situations, MRI is the preferred imaging technique for patients with epilepsy. Advances in radionuclide-based techniques such as single-photon emission CT/positron emission tomography and electromagnetic source imaging with magnetoencephalography are providing new insights into the pathophysiology of epilepsy. In addition, techniques such as magnetic resonance spectroscopy are beginning to impact treatment. In this review, I discuss how these techniques are used in clinical practice but more importantly, how imaging findings play an increasing role in neurotherapeutics.

Epileptic falling spells after epidural haematoma in adult Down's syndrome

A 35-year-old man with Down's syndrome showed epileptic falling spells. He had suffered from a traumatic right-sided epidural haematoma 3 years before. It had been neurosurgically treated, but MRI taken 5 days later had revealed a small contracoup contusion at the left temporal lobe. His falling spell was a brief tonic seizure without disturbance of consciousness. Background activities of EEG consisted of slow alpha waves interspersed with sporadic theta waves and the amplitude at the left temporal area was lower than the opposite one. Interictal EEG showed sharp waves or sharp and slow wave complexes predominantly at the right temporo-centro-parietal area as well as diffuse, though predominantly at frontal areas, bursts of slow waves with high amplitude. The EEG suggested focal epileptic activities evolving into secondary generalization. SPECT of the brain showed the hypoperfusion at the left temporal area and at the right posterotemporo-parietal area, where the hypoperfusion was somewhat reduced after the improvement of seizures. Seizures were well controlled with phenytoin combined with phenobarbital. The incidence of epilepsy in the Down's syndrome has been reported to increase after the middle age in association with the development of Alzheimer's neuropathology. When those people would sustain head injuries, it was necessary to follow carefully using SPECT and EEG.

Brain imaging during seizure: ictal brain SPECT

The role of single photon computed tomography (SPECT) in presurgical localization of medically intractable complex partial epilepsy (CPE) in children is reviewed. 99mTechnetium Neurolite, a newer lipophylic agent with a high first pass brain extraction and little or no redistribution is injected during a seizure, while the child is monitored with a video recording and continuous EEG and SPECT imaging is performed in the next 1-3 hours with the images representing regional cerebral profusion at the time of injection. On SPECT studies performed with radiopharmaceutical injected during a seizure, ictal focus is generally hypervascular. Other findings on ictal brain SPECT include hypoperfusion of adjacent cerebral cortex and white matter, hyperperfusion of contralateral motor cortex, hyperperfusion of ipsilateral basal ganglia and thalamus, brain stem and contralateral cerebellum. Ictal brain SPECT is non-invasive, cost effective and highly sensitive for localization of epileptic focus in patients with intractable CPE.

Usefulness of ictal and interictal 99mTc ethyl cysteinate dimer single photon emission computed tomography in patients with refractory partial epilepsy

PURPOSE

Ictal perfusion single photon emission computed tomography (SPECT), using HMPAO, has been shown to localize epileptic foci in approximately 90% of studies. Unfortunately, HMPAO decomposes rapidly, precluding the performance of ictal studies. Ethyl cysteinate dimer (ECD) is a SPECT perfusion agent recently approved by the Food and Drug Administration. After preparation, this compound is stable for approximately 6 h. facilitating the performance of ictal studies.

METHODS

In a prospective, open-label, uncontrolled, non randomized study, we evaluated the potential benefits of the use of 99mTc-ECD SPECT for lateralization of the epileptic focus. Ten consecutive adult epilepsy surgery candidates were studied with ictal and interictal 99mTc-ECD SPECT.

RESULTS

The mean delay between seizure onset and ictal SPECT injection was 23.2 s. The mean seizure duration was 84.1 s. Ictal studies agreement between the epilepsy focus and area of hyperperfusion was evident in 8 of 10 cases. In one case, SPECT was lateralized in a patient with bilateral temporal lobe epilepsy (TLE); however, hyperperfusion was observed on the same side of that particular seizure. In another case, there was location disagreement. Interictal SPECT showed focal hypoperfusion in three cases.

CONCLUSIONS

99mTc-ECD proved to be an optimal tracer for ictal studies. Although this is a small series, the results of ictal and interictal findings using 99mTc-ECD are similar to those reported with 99mTc-HMPAO. Because 99mTc-ECD has a longer decomposition time, true ictal studies are easier to obtain. This new tracer will probably allow the use of ictal SPECT to become widely accepted in most epilepsy centers.

Brain SPECT imaging of neuropsychiatric disorders

Brain imaging has become an integral part of the evaluation of neurological and psychiatric disorders. Functional imaging techniques, SPECT and PET, together with structural modalities, CT and MRI, are widely employed. Functional imaging studies are routinely used in the diagnostic workup of patients with well-characterized neurological disorders, such as epilepsy and brain tumors, and have a growing role in research on psychiatric disorders without known mechanisms such as depression and schizophrenia. Furthermore, many well-defined neurological disorders manifest prominent psychiatric symptomatology which may pose difficulties in differential diagnosis. This review addresses the current knowledge of SPECT findings in patients who present with psychiatric phenomena, associated with disorders at the interface of neurology and psychiatry.

SPECT (Single Photon Emission Computed Tomography) in 31 children and adolescents with autism and autistic-like conditions

SPECT with Tc-99m-HM-PAO was used in examining 31 patients with autism and autistic-like conditions. Sixteen of these had autistic disorder/autistic-like conditions with associated epilepsy. The autistic disorder group without epilepsy was relatively high functioning. All 31 patients showed reduction of regional cerebral blood flow in the temporal lobes. There was no clear difference between the groups with and without epilepsy, suggesting that seizure disorder per se could not account for the findings.