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Magnetic resonance imaging (MRI) was performed after complex febrile convulsions (CFCs) in 27 infants. Definite MRI abnormalities were seen in 6 of the 15 infants with focal or lateralized CFCs and in none of the 12 infants with generalized CFCs. In 2 of the 6 infants with lateralized CFCs and abnormal MRIs, the MR images showed preexisting bilateral hippocampal atrophy consistent with the history of perinatal insults in these infants. However, the remaining 4 infants with MRI abnormalities and lateralized CFCs had significantly longer seizures than other infants and had MRI changes suggesting acute edema with increased hippocampal T2-weighted signal intensity and increased volume predominantly in the hippocampus in the hemisphere of seizure origin. Of those with acute edema, 1 had electrographical seizure activity recorded in the temporal region and another had a choroid fissure cyst displacing the affected hippocampus; both infants had follow-up MRIs showing that hippocampal atrophy had developed. These patients demonstrate that prolonged and focal CFCs can occasionally produce acute hippocampal injury that evolves to hippocampal atrophy. Finally, evidence of preexisting hippocampal abnormalities in several infants and electrographical temporal lobe seizure activity in 1 suggests the possibility that CFCs actually originated in the temporal lobes in some patients.

The limbic system seems to be involved in the pathophysiology of neuropsychiatric disorders, including dementia, schizophrenia, affective disorders, and amnestic disorders. These findings are subtle and largely went undetected until the advent of modern neuroimaging. This article discusses some of the neuroimaging findings in these disorders.

Leptomeningeal enhancement on CT and MR imaging studies secondary to cryptococcal meningitis is an uncommon finding. In immunocompromised patients, this meningitis incites only a mild inflammatory reaction and abnormalities are often absent on imaging studies. We recently encountered two patients with cryptococcal meningitis in whom postcontrast MR imaging showed thick enhancing subarachnoid spaces. Both had cryptococcal meningitis at autopsy. In a different patient with cryptococcal meningitis, postmortem MR imaging and pathologic examinations showed that these areas of enhancement correspond to abundant mucoid material secreted by the yeasts.

Congenital anomalies of the vertebral artery, including aneurysms and fenestrations, or partial duplication of the extracranial vertebral artery are rarely seen. Presented here is an unusual case of bilateral congenital anomalies of the extracranial vertebral arteries. The right vertebral artery demonstrated an aneurysm and the left a partial duplication. The aneurysm was felt to be the source of the embolic phenomenon to the posterior circulation. This was treated with detachable balloon catheter placement.

A 5-year-old girl presenting with acute middle cerebral artery stroke was diagnosed as having intracranial fibromuscular dysplasia by angiographic findings of focal changes in the proximal right middle cerebral artery and pathological dilatation of the right internal carotid artery at the base of the skull, as well as dissection of at least one of the middle cerebral artery branches and nonfilling of two or perhaps three remaining middle cerebral artery segmental branches. Her clinical condition improved after management of the increased intracranial pressure. She did not receive any medication after discharge and had virtually no residual sequelae. Our case documents an unusual location and age of onset of a patient with fibromuscular dysplasia.

A 32-month-old child presented in status epilepticus (SE) involving the left side of the body. Fast spin-echo magnetic resonance imaging (FSE-MRI) with hippocampal volumetry performed < or = 24 h after the seizure showed increased T2 signal of the right hippocampus, but no atrophy. Complex partial seizures (CPS) appeared at age 33 months, and three more episodes of SE occurred between 33 and 37 months of age. Follow-up FSE-MRI at 34 and at 45 months of age demonstrated progressive hippocampal atrophy with resolution of the increased T2 signal. Her CPS became intractable and, at age 51 months, she underwent right temporal lobectomy. In the ensuing 5 months, she has had only one major motor seizure. This case demonstrates that acute increased hippocampal T2 signal intensity can occur soon after SE and hippocampal sclerosis (HS) may become evident within months in the setting of recurrent early childhood SE. This observation may support the hypothesis that early childhood SE can lead to HS. Furthermore, this case suggests that years of temporal lobe CPS may not be necessary for development of HS.

The limbic system refers to the part of the brain that is involved in emotional expression and in cognitive and somatomotor control systems; it most likely also has a significant role in the pathogenesis of certain dementias, neuropsychiatric disturbances, and seizure disorders. This system, as originally defined, has no clear anatomic boundaries. Limbic regions of the telencephalon include a continuous medial zone of cortical regions, including the hippocampal formation; a perihippocampal zone, including the cingulate gyrus, prefrontal region, and perirhinal region; along with subcortical areas, including the septum pellucidum and the amygdala. A distinguishing characteristic of the limbic region is that it is highly interconnected and appears to form the only major route for information transfer between the neocortex and the hypothalamus. With the multiplanar capability and resolution of MR imaging, the individual parts of the limbic system and the diseases that affect them can be studied. In this review, we discuss MR imaging of the diseases that affect this system.

Neurological endemic cretinism, resulting from severe iodine deficiency, is characterized by mental deficiency, deafmutism, and a spastic-rigid motor disorder. Its neuropathology and pathophysiology have been investigated very little. We report the clinical and magnetic resonance imaging brain scan findings of 3 adult Chinese cretins. All show an apparent magnetic resonance imaging abnormality in the globus pallidus and substantia nigra, with hyperintensity on T1-weighted images and hypointensity on T2-weighted images. The motor abnormality, characterized by truncal and proximal limb-girdle rigidity and spasticity, with relative sparing of the hands and feet, is analogous to other extrapyramidal disorders. Endemic cretinism is a unique form of cerebral palsy of potential interest for students of human neuromotor development.