Postcontrast MRI of cranial meninges: leptomeningitis versus pachymeningitis.

OBJECTIVE: Our goal was to characterize the patterns of meningeal enhancement in postcontrast MR images and correlate these patterns with the clinical disorders. MATERIALS AND METHODS: The MR scans, medical records, and laboratory findings of 83 patients, whose postcontrast MR studies of the head demonstrated meningeal enhancement, were reviewed retrospectively. The patterns of enhancement of the different layers of the meninges were divided into two types: leptomeningeal (pia and arachnoid), when enhancement of the meninges followed the convolutions of the gyri and/or involved the meninges around the basal cisterns; and pachymeningeal (dura), when the enhancement was thick and linear or nodular along the inner surface of the calvarium, falx, or tentorium without extension into the cortical gyri or basal cistern involvement. Enhancement around the basal cistern was considered leptomeningeal, since the dura-arachnoid is widely separated from the pia-arachnoid in this region. Further, the meningeal enhancement was divided into five etiologic subgroups, i.e., carcinomatous, infectious, inflammatory, reactive, and chemical. The medical history, clinical presentation, and findings on CSF analysis were used to distinguish infectious from carcinomatous meningitis. Meningeal enhancement due to surgery, shunt, or trauma was considered reactive, while ruptured cysts (dermoid or cysticercoid) or intrathecal chemotherapy were classified as chemical meningitis. Meningitis secondary to involvement by collagen vascular disease or sarcoidosis was considered to be inflammatory. RESULTS: Thirty of the 83 subjects had carcinomatous, 28 infectious, 14 reactive, 8 chemical, and 3 inflammatory etiology for meningitis. Twenty-five cases (83%) of the carcinomatous, 14 (100%) of the reactive, 3 (100%) of the inflammatory, and 1 (12%) of the chemical meningitis subgroups demonstrated pachymeningeal enhancement, while 28 cases (100%) of the infectious meningitis and 7 (78%) of the chemical meningitis subgroups had leptomeningeal enhancement. Only five cases (17%) of the carcinomatous meningitis subgroup showed leptomeningeal enhancement. Four of these five cases were as a result of direct spread of intraparenchymal tumors or through perineural extension, rather than hematogenous involvement. Only one patient with carcinomatous meningitis demonstrated leptomeningeal enhancement without clear intraparenchymal lesion. CONCLUSION: The recognition of various patterns of meningeal enhancement (leptomeningitis versus pachymeningitis) may help in differentiating between infectious and carcinomatous meningitis. This study demonstrated that infectious meningitis presents mostly as leptomeningitis, while carcinomatous meningitis presents as pachymeningitis.

Central nervous system tuberculosis: MRI.

The MRI findings of 18 proven cases of central nervous system (CNS) tuberculosis were reviewed; 10 patients were seropositive for HIV. All had medical, laboratory, or surgical proof of CNS tuberculosis. Eleven patients had meningitis, of whom two also had arachnoiditis. Five patients had focal intra-axial tuberculomas: four brain masses and one an intramedullary spinal lesion. Two patients had focal extra-axial tuberculomas: one in the pontine cistern, and one in the spine. In all 11 patients with meningitis MRI showed diffuse, thick, meningeal enhancement. All intraparenchymal tuberculomas showed low signal intensity on T2-weighted images and ring or nodular enhancement. The extra-axial tuberculomas had areas isointense or hypointense relative to normal brain and spinal cord on T2-weighted images. Although tuberculous meningitis cannot be differentiated from other meningitides on the basis of MR findings, intraparenchymal tuberculomas show characteristic T2 shortening, not found in most other space-occupying lesions. In the appropriate clinical setting, tuberculoma should be considered.

Imaging of pregnancy-related complications.

Thirty-six cases of pregnancy-related complications were studied with plain radiography, ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging alone or in combination. Among the complications diagnosed with these various techniques were venous thromboembolic disorders, deep vein thrombosis, ovarian vein thrombosis, endometritis and pyometra, HELLP syndrome (hemolysis, elevated liver enzyme levels, and low platelet counts), hepatic hematoma and rupture, fatty liver, uterine rupture, various hematomas and a foreign body, tubo-ovarian abscess, cerebral venous thrombosis, cerebral ischemia, and cerebral edema. Prompt detection and appropriate management of many of these complications could result in decreased maternal and fetal mortality and morbidity. Although US should be considered first because it can be performed bedside, does not require use of ionizing radiation, and is cost-effective, CT is superior in demonstrating the extent of the abnormality and MR imaging is best for detection of neurologic complications of pregnancy. The radiologist should select the best available method and tailor the examination according to the presumptive clinical diagnosis and the individual problem to be solved.

Value of acute-phase angiography in the detection of vascular injuries caused by gunshot wounds to the head: analysis of 12 cases.

A study of the angiographic findings in consecutive civilian patients with cranial gunshot wounds examined in the acute stage has not been done. Most prior clinical studies have evaluated the findings in survivors in the subacute or chronic stages and have often been of war-time casualties. We determined the clinicoradiologic features of six cases of posttraumatic intracranial aneurysm, vascular occlusion, or arteriovenous fistula caused by penetrating missiles among 12 civilian patients who were examined in the acute posttraumatic stage (within 48 hr of injury) during a 1-year period. Three internal carotid/vertebral artery aneurysms, one external carotid artery aneurysm, one combined aneurysm/arteriovenous fistula of the vertebrobasilar circulation, and one cerebral venous occlusion were identified. The 50% overall prevalence of major vascular lesions in this series of civilian patients with penetrating missile injuries examined in the acute stage suggests these injuries are more common than previously suspected. It may indicate that selective cerebral angiography should be considered in the evaluation of the cranial vascular system of such persons.

Cauda equina syndrome of long-standing ankylosing spondylitis. Case report and review of the literature.

Cauda equina syndrome as a neurological complication of long-standing ankylosing spondylitis was first reported in 1961. The syndrome is relatively uncommon and its pathophysiology is still poorly understood. Based on their experience with such a case, the authors review the clinical, electrographic, histological, and radiographic features of the syndrome, including the findings of magnetic resonance (MR) imaging. The addition of MR imaging to the evaluation of patients with ankylosing spondylitis and the cauda equina syndrome not only aids in the diagnosis of the syndrome but may also provide valuable insight into the pathophysiology of this condition.

Peripheral vascular gunshot bullet embolus migration to the cerebral circulation. Report and literature review.

Bullet embolization to intracranial branches of the major cerebral arteries is a rare complication of gunshot wounds. A review of the literature on cerebral vascular bullet embolization from peripheral sources revealed a number of single case reports that included 12 cases involving the anterior cerebral circulation, and one which involved the posterior circulation. This communication details two additional subjects who were treated at our institution.

Rotational vertebrobasilar insufficiency secondary to vertebral artery occlusion from fibrous band of the longus coli muscle.

Rotation-induced vertebrobasilar artery hypoperfusion causes transient ischemic attacks (TIAs), affecting the cerebellum, brainstem and spinal cord. When these symptoms occur transiently due to head movement, compression of the vertebral artery by an extraluminal lesion should be suspected. Cervical spondylotic spurs and anterior scalene muscle or deep cervical fascia are among the factors which can compress the vertebral artery. When symptoms of vertebrobasilar insufficiency occur with rotational head movement, subclavian angiography for visualization of the entire vertebral artery in both neutral and rotated head positions should be undertaken.