The authors investigated the spectrum of radiologic findings in a large series (n = 47) of patients seropositive to human immunodeficiency virus (HIV) 1 and with pathologically proved progressive multifocal leukoencephalopathy, to determine the characteristic imaging pattern of the disease. Thirty-six computed tomographic (CT) scans and 29 magnetic resonance (MR) imaging studies obtained in the 47 patients were retrospectively reviewed and correlated with pathologic and clinical findings. Contrast agents were used in 32 CT procedures and 13 MR imaging studies. Lesions typically were hypoattenuating on CT scans and were characterized by areas of increased signal intensity without mass effect on dual-echo MR images. Lesions most often involved periventricular and subcortical white matter in parietooccipital or frontal lobes. Fifteen patients had posterior fossa lesions, and disease was limited to the posterior fossa in two. Lesions were also in the corpus callosum (seven patients), thalamus (eight patients), and basal ganglia (seven patients). In comparison with CT, MR imaging demonstrated greater sensitivity for the extent and number of lesions.

The development of cerebral aneurysmal arteriopathy in childhood AIDS tends to occur after a prolonged delay and is usually followed by death in a short period of time. The etiology for the vasculitis is unknown. Varicella zoster virus may be the etiology in some of the cases because of its potential to cause this pathology and the striking unilateral arterial involvement found in Case 5. HIV vasculitis is also a possibility, as suggested by the detection of HIV protein or genomic material in two of the four autopsy cases.

The acute traumatic central cord syndrome (ATCCS) is commonly stated to result from an injury which affects primarily the center of the spinal cord and is frequently hemorrhagic. To test the validity of this widely disseminated hypothesis, the magnetic resonance images [MRI] of 11 consecutive cases of ATCCS caused by closed injury to the spine were analyzed and correlated with the gross pathological and histological features of 3 cervical spinal cords obtained at post mortem from patients with ATCCS, including 2 of patients studied by MRI. The MRI studies were performed acutely (18 h to 2 days after injury) in 7 patients and subacutely (3-10 days after injury) in 4. Ten of the 11 patients had pre-existing spondylosis and/or canal stenosis. The 11th suffered a cervical fracture. All patients exhibited hyperintense signal within the parenchyma of the cervical spinal cord on gradient echo MRI. None showed MRI features characteristic of hemorrhage on T1-weighted spin echo or T2-weighted gradient echo studies. Gross and histological examination of the necropsy specimens showed no evidence of blood or blood products within the cord parenchyma: the primary finding was diffuse disruption of axons, especially within the lateral columns of the cervical cord in the region occupied by the corticospinal tracts. The central gray matter was intact. In patients with ATCCS, the predominant loss of motor function in the distal muscles of the upper limbs may reflect the importance of the corticospinal tract for hand and finger function in the primate. In this study, the MRI and pathological observations indicate that ATCCS is predominantly a white matter injury and that intramedullary hemorrhage is not a necessary feature of the syndrome; indeed, it is probably an uncommon event in ATCCS. We suggest that the most common mechanism of injury in ATCCS may be direct compression of the cervical spinal cord by buckling of the ligamenta flava into an already narrowed cervical spinal canal; this would explain the predominance of axonal injury in the white matter of the lateral columns.

DILATED EPISCLERAL ARTERIES/Cow/»ee et al. 45carotid artery occlusion. Dilated episcleral arteries, particularly in the absence of other stigmata of ocular ischemia, strongly suggest that the external carotid artery is the major source of blood supply to the homolateral cerebral hemisphere. Consequently, maintaining patency of the external carotid artery in these situations is important. OVER 50 YEARS AGO, Sydensticker 1 established that sickle cell anemia (SCA) could have prominent neurologic manifestations. A recent review of 89 cases of SCA, proven by electrophoresis to be homozygous for hemoglobin (SS), showed that 29% of the patients had developed neurological complications, and that 17% had had strokes. References2 The patient with SCA we studied arrived in coma as the result of bilateral carotid artery occlusion. Angiography revealed a pattern which is consistent with Moyamoya disease. An autopsy showed thrombosis of major intracranial vessels while intimal hyperplasia, unusual in SCA, was also present. Clinical FeaturesA 7-year-old black boy was admitted to Jackson Memorial Hospital with an acute alteration of consciousness. The patient was originally diagnosed as having sickle cell anemia at the age of 7 months. Originally he had edema of both hands and feet, was anemic, and had a positive sickle cell preparation. Subsequently, he had several hemolytic crises. Seven months before this last admission, the child developed a right hemiparesis with hemianesthesia and Broca's aphasia. This was accompanied by focal myoclonic seizures involving his right arm and the right side of his face. He was given phenytoin and improved, but 4 months later he suffered a similar episode, which left him with moderately severe expressive aphasia. A Tc99 (Technetium) brain scan was diagnostic for occlusion of the left middle cerebral artery. His hemoglobin ranged between 6-8 gm/dl, and his reticulocyte count between 10-40%. Prior to his last admission he had been irritable and was later found comatose. In the emergency room, he was stuporous, and had right spastic hemiparesis, a right gaze preference and right-beating jerk nystagmus. His hemoglobin was 6.9 gm/dl, with a white cell count of 17,400 per mm 3 and 16% reticulocytes. The cerebrospinal fluid contained 11 white blood cells per mm, 8 (45% granulocytes). He was treated with phenobarbital and diazepam and became more alert. Subsequently, an EEG revealed bilateral slowing, more marked on the left. Three days later, he became febrile (102.4°F) and more lethargic. Examination revealed nuchal rigidity and a positive Brudzinski sign. A second spinal tap showed 6850 red cells and 340 white cells per mm 3 with 55% granulocytes and a protein of 322 mg/dl; CSF glucose levels were normal. Cultures of spinal fluid, blood and urine were all negative. A brain scan (Tc99) showed another area of increased uptake in the posterior right hemisphere. The child was treated with penicillin and a transfusion of 1000 ml packed cells after which he improved slightly. Hemoglobin electrophoresis...

Cidofovir did not improve neurological examination scores at week 8. However, such scores were significantly better in subjects who entered with suppressed plasma HIV-1-RNA levels, which could be the result of control of HIV-1 infection itself or cidofovir.

Findings on cranial magnetic resonance (MR) images were correlated with known histopathologic findings in 42 patients with tuberous sclerosis (TS), 17 of whom received gadopentetate dimeglumine, to extend the range of signs on MR images. Four neuroradiologists recorded the number, sites, configurations, and relative signal intensities of intracranial abnormalities. White matter lesions, found in 39 patients (93%), showed four distinct patterns: (a) straight or curvilinear bands extending radially from the ventricle through the cerebral mantle toward the cortex, (b) wedge-shaped lesions, (c) nonspecific conglomerate foci, and (d) cerebellar radial bands. It is concluded that cortical tubers, white matter lesions, subependymal nodules, and sub-ependymal giant cell astrocytomas (SGCAs) may be enhanced after administration of gadopenetetate dimeglumine. Enhancement of a TS lesion does not indicate neoplastic transformation into SGCA. Imaging surveillance every 12 months appears indicated during the peak ages (8-18 years) of occurrence of SGCA. The appearance of white matter lesions supports the theory that the cerebral lesions of TS may be caused by disordered migration of dysgenetic cells.

Evaluation of intracranial and intraspinal CSF flow was accomplished by the use of cardiac gated gradient echo magnetic resonance (MR) technique. Normal patterns of pulsatile flow within the ventricles, cisterns and cervical subarachnoid space were established by this technique and these observations were compared to prior description of CSF flow. With systole there is downward (caudal) flow of CSF in the aqueduct of Sylvius, the foramen of Magendie, the basal cisterns and the dorsal and ventral subarachnoid spaces while during diastole, upward (cranial) flow of CSF in these same structures is seen. The relationships between the cardiac cycle and the CSF pulsations are demonstrated on both magnitude reconstruction and phase reconstruction MR images. Calculations of actual fluid velocity within CSF containing spaces can be obtained from the phase reconstruction images and holds promise for a more accurate analysis of CSF flow. In conditions which result in alterations of flow, cine MR dramatically shows either obstruction or excessively turbulent flow within the CSF pathways. The site of obstructed flow whether in the third ventricle, aqueduct, fourth ventricle, or subarachnoid space can be appreciated by changes in or absence of the normal hypointense signal. Cystic cord lesions such as congenital syringohydromyelia and posttraumatic spinal cord cysts may show pulsatile flow of CSF, a fact which can relate to progressive enlargement of these cysts. The distinction between myelomalacia and cyst formation in the cord is facilitated by the technique. Although the use of cine MR for the analysis of CSF flow is in its infancy, our experience indicates that this technique is useful in a wide range of pathological conditions including, but not limited to, conditions resulting in hydrocephalus or cystic cord lesions.

Our study showed that toxoplasmosis exhibits a wide spectrum of diffusion characteristics with ADC ratios which have significant overlap with those of lymphoma. Therefore, in the majority of patients, ADC ratios are not definitive in making the distinction between toxoplasmosis and lymphoma.