Ultrasonografía del diámetro de la vaina del nervio óptico en paciente con meningoencefalitis complicada / Ultrasonography of the optic nerve sheath diameter in patient with complicated meningoencephalitis

RESUMEN La ultrasonografía del diámetro de la vaina del nervio óptico es un método no invasivo para monitorizar la presión intracraneal. Se ha utilizado en múltiples patologías neurocríticas, incluyendo la infección complicada del sistema nervioso central. Se presenta el caso de una paciente femenina de 47 años, quien ingresó en la Unidad de Cuidados Intensivos luego de presentar progresión al estado comatoso secundario a cuadro de meningoencefalitis bacteriana. Al ingreso se constata midriasis bilateral arreactiva, ausencia parcial de reflejos del tallo encefálico y bradicardia. Ante la sospecha clínica de hipertensión intracraneal, se indica ultrasonografía del diámetro de la vaina del nervio óptico en plano axial. Se realizaron tres mediciones para cada ojo, mostrando un valor de 6,3, 6,6 y 6,00 mm en ojo derecho, y 6,8, 6,6 y 6,8 mm en el izquierdo (promedio biocular: 6,5 mm). Con esta medición se complementó el diagnóstico sospechado. Esta técnica representa un proceder seguro y no invasivo. Su uso completa los datos recogidos en el examen clínico. El punto de corte universalmente aceptado para el diagnóstico es de 5,0 mm o más para un valor de presión intracraneal > 20 mmHg.

ABSTRACT The optic nerve sheath ultrasonography is a non-invasive method for monitoring intracranial pressure. It has been used in multiple neurocritical pathologies, including the complicated infection of the central nervous system. The case of a 47-year-old female patient is presented; she was admitted to the Intensive Care Unit after presenting progression to comatose state secondary to bacterial meningoencephalitis. On admission, bilateral arreactive mydriasis, partial absence of brainstem reflexes and bradycardia are confirmed. Given the clinical suspicion of intracranial hypertension, ultrasonography of the optic nerve sheath diameter in the axial plane is indicated. Three measurements were made for each eye, showing a value of 6.3, 6.6 and 6.00 in the right eye, and 6.8, 6.6 and 6.8 in the left one (biocular average: 6.5 mm). With this measurement the suspected diagnosis was completed. This technique represents a secure and non-invasive procedure. Its use completes the data collected in the clinical examination. The universally accepted cut-off point for diagnosis is 5.0 mm or more for an intracranial pressure value of > 20 mmHg.

Rapidly Aggravated Creutzfeldt-Jacob Disease: Autopsy-Proven Case

Creutzfeldt-Jakob disease (CJD) is one of the transmissible spongiform encephalopathies, which is mediated by what has been known as "prion". It is a rare and fatal progressive neurodegenerative disease that affects the middle and old aged. There are a number of subtypes of CJD, one of which is the sporadic type characterized by rapidly progressing clinical symptoms, including progressive dementia, myoclonic jerk, and pyramidal or extrapyramidal syndrome. Patients usually end up dying within 1 to 2 years of contacting the disease. We report an autopsy-proven case of sporadic CJD with clinical symptoms that progressed within several days, along with dramatic changes on diffusion weighted magnetic resonance images.

The principle and clinical application of diffusion-weighted MR imaging / 医学研究生学报

Different from conventional MRI, Diffusion-weighted(DW) magnetic resonance(MR)imaging is dependent on the molecular motion of water, and provides information on the physiologic state of the brain. In the diagnosis of acute cerebral infarction,the sensitivity is 94% and specificity is 100%. On MRDW imaging, the epidermoid tumors and cerebrospinal fluid or arachnoid cysts, subdura effusions and subdural empyemas,abscess cavities or empyemas and necrotic tumors could be differentiated accurately. MRDW imaging also provides adjunctive information for the diagnosis and evaluation of other cerebral diseases including neoplasms, intracranial infections, traumatic brain injury, and demyelinating processes. As a valuable technique, diffusion-weighted MR imaging should be considered an essential sequence on the diagnosis of brain stroke, and its use in most brain MR studies is recommended.

Congenital Cytomegalovirus Infection of the Brain: MR Imaging and Ultrasonographic Findings of Paraventricular Cysts

PURPOSE: Although the neuroradiological findings of congenital cytomegalovirus (CMV) infection are well known, little has been reported concerning the imaging findings of paraventricular cysts occurring in patients with cytomegalovirus infection involving the brain. The purpose of this study is to describe the features of paraventricular cysts observed at MRI and ultrasonography. MATERIALS AND METHODS: MR and ultrasonographic studies of ten patients with congenital cytomegalovirus infections involving the brain were retrospectively reviewed. Diagnosis was confirmed by positive culture of the virus in urine (n=4), the presence of CMV Ig G antibody (n=4), or positive CMV Ig M antibody (n=2), and on the basis of characteristic MR imaging findings. Initial MRI in all patients and initial ultrasonography in four of five with paraventricular cysts were performed. Three patients underwent follow-up MRI and ultrasonography for the evaluation of cystic change, and the size, location, bilaterality and morphology of the cysts were evaluated. RESULTS: Bilateral paraventricular cysts averaging 15 (range. 10-23) mm in size were found in five of the ten patients (50%). They were adjacent to the foramen of Monro in three cases, the occipital horn in one, and the temporal horn in one. MR imaging showed that the fluid content of all cysts was of similar signal intensity to cerebrospinal fluid (T1-WI, hypointense; T2-WI, hyperintense). The ultrasonographic findings varied: there was one pure cyst and one with a thick wall and septations, and two contained complex fluid. In three patients, follow up MRI and ultrasonography showed that the cysts disappeared after 4-23 months. CONCLUSION: Although paraventricular cysts may appear at MRI to be purely cystic, ultrasonography may indicate that their contents are more complex, or that septations are present.

Diffusion-Weighted MR Imaging in Biopsy-Proven Creutzfeldt-Jakob Disease

OBJECTIVE: To compare conventional and diffusion-weighted MR imaging in terms of their depiction of the abnormalities occurring in Creutzfeldt-Jakob disease. MATERIALS AND METHODS: We retrospectively analyzed the findings of conventional (T2-weighted and fluid-attenuated inversion recovery) and diffusion-weighted MR imaging in four patients with biopsy-proven Creutzfeldt-Jakob disease. The signal intensity of the lesion was classified by visual assessment as markedly high, slightly high, or isointense, relative to normal brain parenchyma. RESULTS: Both conventional and diffusion-weighted MR images demonstrated bilateral high signal intensity in the basal ganglia in all four patients. Cortical lesions were observed on diffusion-weighted MR images in all four, and on fluid-attenuated inversion recovery MR images in one, but in no patient on T2-weighted images. Conventional MR images showed slightly high signal intensity in all lesions, while diffusion-weighted images showed markedly high signal intensity in most. CONCLUSION: Diffusion-weighted MR imaging is more sensitive than its conventional counterpart in the depiction of Creutzfeldt-Jakob disease, and permits better detection of the lesion in both the cerebral cortices and basal ganglia.

Unusual Acute Encephalitis Involving the Thalamus: Imaging Features

OBJECTIVE: To describe the brain CT and MR imaging findings of unusual acute encephalitis involving the thalamus. MATERIALS AND METHODS: We retrospectively reviewed the medical records and CT and/or MR imaging findings of six patients with acute encephalitis involving the thalamus. CT (n=6) and MR imaging (n=6) were performed during the acute and/or convalescent stage of the illness. RESULTS: Brain CT showed brain swelling (n=2), low attenuation of both thalami (n=1) or normal findings (n=3). Initial MR imaging indicated that in all patients the thalamus was involved either bilaterally (n=5) or unilaterally (n=1). Lesions were also present in the midbrain (n=5), medial temporal lobe (n=4), pons (n=3), both hippocampi (n=3) the insular cortex (n=2), medulla (n=2), lateral temporal lobe cortex (n=1), both cingulate gyri (n=1), both basal ganglia (n=1), and the left hemispheric cortex (n=1). CONCLUSION: These CT or MR imaging findings of acute encephalitis of unknown etiology were similar to a combination of those of Japanese encephalitis and herpes simplex encephalitis. In order to document the specific causative agents which lead to the appearance of these imaging features, further investigation is required.

CT Findings of Diffuse Pneumocephalus due to Bacterial Meningitis: A Case Report

We report a case of diffuse pneumocephalus due to infection. Brain CT revealed diffuse brain swelling and diffuse pneumocephalus in the ventricular system, subarachnoid space, subdural/epidural space and superior sagittal sinus. CSF disclosed the presence of a yellowish-green pus-like liquid. Polymerase chain reaction was positive for Haemophilus influenza Ag.

US and MR Imaging of Candidiasis of the Nervous System in Premature Infants: Two Case Reports

Candidiasis of the central nervous system (CNS) is a rare condition and like other opportunistic fungal infections, most commonly occurs in immune-compromised patients. Because of the increasing use of antibiotics and the improving survival rate of premature infants requiring intensive care, the incidence of fungal infections in the brain has increased. We report the findings of ultrasonography and MR imaging in two cases of candidiasis of the CNS in premature infants.

MRI and CT Findings of Intracranial Neurosyphilis

PURPOSE: To evaluate the CT and MRI findings of neurosyphilis. MATERIALS AND METHODS: We retrospectivelyreviewed the CT and MR imaging findings in five patients with intracranial neurosyphilis confirmed by CSF, VDRL,TPHA, and clinical follow-up. MR imaging was performed in all five cases, and CT in two. RESULTS: The MRI and CTfindings of intracranial neurosyphilis included infarction (n=3), focal inflammation (n=1) and encephalopathy(n=1). There was a total of ten infaretions : three of the basal ganglia, two each of the frontal lobe, watershedzone, and cerebellum, and one of the occipital lobe. Intaretion was most common in MCA territory (n=9; 50%),followed by the watershed zone (16.6%), posterior cerebral artery territory (16.6%), and posterior inferiorcerebellar artery territory (11.1%), The size of the lesion varied from 1cm to larger than one lobe. One patientshowed diffuse high signal intensity in the left temporal lobe, but on follow-up MRI, this had resolved. CONCLUSION: The most common finding of neurosyphilis, as seen on MRI and CT, was infarction in middle cerebralarterial territory.

Usefulness of MR Imaging in the Staging of Brain Abscess: Comparison between Experimental Models and Clinical Cases

PURPOSE: The purpose of this study is to evaluate the usefulness of MR imaging in the staging of brain abscesses and to determine the correlations between pathologic and MR findings. MATERIALS AND METHODS: Experimental brain abscesses were induced by direct inoculation of 1ml suspension of l06/ml Streptococcus pneumoniae into the brain parenchyma of ten New Zealand white rabbits. The evolution of abscess formation was divided into four stages, based on pathological criteria: early cerebritis (days 1 to 5), late cerebritis (days 6 to 10), early capsular (days 11 to 15), and late capsular (day 16 and later). The brain abscess of each animal was examined by MR imaging and light microscopy at 3, 8, 13, and 28 days; T1-weighted, T2-weighted and Gd-enhanced images were obtained. The MR images and pathologic findings of 13 pathologically confirmed clinical cases were compared to MR images of the experimental model. RESULTS: In the experimental model, signal intensity of the abscess content was at all stages hypointense on T1-weighted and hyperintense on T2-weighted images. In all ten cases, Gd-enhanced images showed an ill-defined contrast-enhanced lesion at the early cerebritis stage, and in four of seven cases, irregular ring enhancement at the late cerebritis stage. Pathologic specimens at this latter stage revealed prominent vascular proliferation and infiltration of chronic inflammatory cells. Signal intensity of the abscess wall during the capsular stage showed isointense relative brain parenchyma on T1-weighted images and this was hypointense on T2-weighted images. Gd-enhanced images demonstrated smooth ring enhancement of the abscess wall. At the early capsular stage, pathologic specimens revealed a discrete necrotic center surrounded by infiltration of reticulin and some collagen; at the late capsular stage, these specimens showed marked infiltration of collagen. In clinical cases, the signal intensity of abscess content was at all stages hypointenseon T1-weighted and hyperintense on T2-weighted images. Gd-enhanced images demonstrated ill-defined subtle contrast enhancement at the early cerebritis stage and irregular ring enhancement at the late cerebritis stage. In all cases, signal intensity of the abscess wall during the capsular stage was hypointense on T2-weighted images; at this stage, the abscess wall was showed a pattern of smooth ring enhancement. In clinical cases, hypointensity of the abscess wall, as seen on T2-weighted images, and the enhancement pattern of this wall were identical to these findings in the experimental model. CONCLUSION: In an experimental model, correlation between sequential MR findings can be used to predict the stage of a brain abscess; in clinical cases essential indicators are hypointensity and enhancement pattern of the abscess wall, as seen on T2-weighted images. In cases of brain abscess, MRI is a useful diagnostic modality, and in such cases, also helps determine the most suitable treatment.