Non-neoplastic intracranial cystic lesions: not everything is an arachnoid cyst / Lesões císticas intracranianas não neoplásicas: nem tudo são cistos aracnoides

Abstract Intracranial cystic lesions are common findings on neuroimaging examinations, arachnoid cysts being the most common type of such lesions. However, various lesions of congenital, infectious, or vascular origin can present with cysts. In this pictorial essay, we illustrate the main causes of non-neoplastic intracranial cystic lesions, discussing their possible differential diagnoses as well as their most relevant imaging aspects.

Resumo Lesões císticas intracranianas são achados comuns nos exames de neuroimagem, sendo os cistos aracnoides os mais comuns. Porém, muitas outras lesões, de origem congênita, infecciosa e vascular, podem se apresentar com cistos. Neste ensaio ilustramos as principais causas de lesões císticas intracranianas não neoplásicas, discutindo seus possíveis diagnósticos diferenciais, bem como seus aspectos de imagem mais relevantes.

Hypopituitarism Secondary to an Arachnoid Cyst ­ Case Report

Arachnoid cysts (ACs) are a rare condition of mass effect injury and are usually found in the Sylvian fissure. However, rarely, they can appear in the sellar area, causing symptoms of compression. Due to the mass effect, the sellar arachnoid cyst (SAC) may cause headaches, visual disturbances, hypopituitarism, precocious puberty, and the "bobble-head doll" syndrome. We present the case of JNS, 61 years old, male. The patient presented with hypotestosteronism, hypothyroidism, hypocortisolism and bitemporal hemianopsia. The magnetic resonance imaging scans revealed a mass above the pituitary gland, compatible with a SAC. A surgical excision was performed with removal of the capsule and fenestration within the subarachnoid spaces for emptying the cyst. After the procedure, the patient presented great clinical improvement. The rarity of the case calls attention to the fact that SACs should be thought of as a differential diagnosis in cases of hypopituitarism.

Cistos aracnoides são uma condição rara de lesão de efeito de massa e que comumente aparecem na região da fissura silviana. No entanto, raramente, podem aparecer na região selar, ocasionando sintomas de compressão. Devido ao efeito de massa, podem causar dores de cabeça, distúrbios visuais, hipopituitarismo, puberdade precoce e síndrome da "bobble-head doll. " Apresentamos o caso de JNS, 61 anos, do sexo masculino. Paciente com hipotestosteronismo, hipotiroidismo, hipocortisolismo e hemianopsia bitemporal. As imagens de ressonância magnética (RM) revelaram uma massa acima da hipófise, mostrando um cisto aracnoide selar. O paciente foi submetido a excisão cirúrgica com fenestração dentro dos espaços subaracnoides para esvaziamento do cisto e apresentou grande melhora clínica após o procedimento. A raridade deste caso chama atenção para o fato de que o cisto aracnoide selar deve ser considerado como um diagnóstico diferencial em casos de hipopituitarismo.

A retrospective study of quadrigeminal arachnoid cysts diagnosed by Magnetic Resonance Imaging and Computed Tomography in 26 dogs / Estudo retrospectivo de cistos aracnoides da cisterna quadrigeminal diagnosticados pela ressonância magnética e tomografia computadorizada em 26 cães

Arachnoid cysts are accumulations of cerebrospinal fluid that occur within the arachnoid membrane due to the splitting or duplication of this structure. The aim of this retrospective study is to report the occurrence of this condition in 26 dogs, as well as to describe the findings of computed tomography imaging and magnetic resonance image scans and to correlate these with the clinical signs. A prevalence of the condition was observed in males, predominantly in the small breeds Miniature Pinscher and Shih Tzu, with age raging from 2 months to 9 years. The mainly clinical signs observed in these dogs were seizures and cerebellar ataxia. The study concluded that in 17 dogs the quadrigeminal arachnoid cyst was regarded as an incidental finding, in 6 dogs this condition was regarded as the determinant cause of the clinical signs, and in 3 dogs some clinical signs were associated with arachnoid cyst, but they also presented clinical signs involving others sites of intracranial lesion. (AU)

Cistos aracnoide são acúmulos de líquido cefalorraquidiano que ocorre dentro da membrana aracnoide devido à divisão ou duplicação desta estrutura. O objetivo desse estudo retrospectivo é relatar a ocorrência dessa condição em 26 cães, assim como descrever os aspectos de imagem pela tomografia computadorizada e ressonância magnética e correlacionar com os sinais clínicos. No estudo observamos a prevalência em machos, em raças de pequeno porte, com predomínio de Pinscher miniatura e Shih Tzu, com idade variando de dois meses a nove anos. Os principais sinais neurológicos observados nestes animais foram crises epiléticas e ataxia cerebelar. Foi possível concluir que em 17 cães o cisto aracnoide quadrigeminal foi considerado um achado incidental, em seis cães essa condição foi considerada a causa determinante dos sinais clínicos, e em três cães alguns sinais estavam associados com o cisto aracnoide, porém esses animais apresentaram sinais clínicos relacionados a outros sítios de lesão intracraniana.

Aracnoidocele selar como causa de hiponatremia severa. Presentación de un caso y revisión de la literatura

El síndrome primario de la silla turca vacía o aracnoidocele selar se presenta cuando una de las capas que cubre la parte externa del cerebro protruye hacia abajo en la silla y ejerce presión sobre la hipófisis. En el caso del hipopituitarismo, como causa de aracnoidocele, las manifestaciones clínicas dependen del aumento o disminución de la producción de hormonas, lo que lleva a la aparición de trastornos hidrominerales severos como la hiponatremia. Se presenta el caso de una paciente que acudió al Hospital Dr. Gustavo Aldereguía Lima con cuadro clínico de vómitos, decaimiento, malestar general, pérdida del apetito y ureas escasas. Durante su ingreso, la paciente presentó un cuadro de estado convulsivo que llevó a la ventilación mecánica. Se realizaron estudios tomográficos que fueron negativos y al analizar el resto de los exámenes de laboratorio, se diagnosticó un hipotiroidismo con hiponatremia severa para lo cual se indicó tratamiento. Se realizó una resonancia magnética nuclear donde se determinó un aracnoidocele selar grado III. Se presenta este reporte por la importancia del diagnóstico y tratamiento oportunos de esta entidad.

The primary syndrome of the ¨empty¨ sella turcica or sellar diaphragm herniation appears when one of the layers which cover the outside of the brain protrudes down into the sella and puts pressure on the pituitary. In the case of hypopituitarism, as a cause of arachnoid hernia, clinical manifestations depend on increased or decreased production of hormones, leading to the appearance of severe hydromineral disorders such as hyponatremia. It is presented a case of a patient who came to Dr. Gustavo Aldereguía Lima Hospital with clinical symptoms of vomiting, decay, general malaise, loss of appetite and scarce urination. During admission, the patient had a convulsive status which led to mechanical ventilation. We performed tomography studies that were negative and when analyzing the rest of the laboratory tests, hypothyroidism with severe hyponatremia was diagnosed for which treatment was indicated. A nuclear magnetic resonance was performed where a grade III sellar diaphragm herniation was diagnosed. This report is presented because of the importance of timely diagnosis and treatment of this entity.

Caracterización del realce meníngeo intracraneal / Intracranial Meningeal Enhancement Characterization

Objetivo: Describir las características del realce meníngeo intracraneal (RMI) como hallazgo en resonancia magnética y su comportamiento según las diferentes patologías asociadas descritas en la literatura científica. Materiales y métodos: Estudio descriptivo de corte transversal realizado con información recolectada de 89 estudios, entre enero y diciembre de 2011, en los cuales se encontró realce meníngeo como hallazgo positivo en la lectura original. Cada estudio fue sometido a nueva revisión por un neurorradiólogo para la caracterización morfológica del realce meníngeo. Resultados: Las causas más frecuentes de RMI fueron enfermedad metastásica (21,3 %), etiología infecciosa (21,3 %), antecedente de cirugía intracraneal (20,2 %) y neoplasias primarias (13,5 %). Del total de las infecciones del sistema nervioso central (19 casos) se documentó infección por VIH en 12 pacientes (70,6 %). El paciente con antecedente quirúrgico de mayor antigüedad fue sometido a craneotomía 17 años antes de la toma de la resonancia magnética incluida en el estudio, en la cual persiste el realce aunque no se han definido signos de recidiva por imagen o por clínica hasta 2015. El tipo de realce más frecuente fue el leptomeníngeo (46,1 %), seguido del mixto (43,8 %) y el paquimeníngeo (10,1 %). En el subgrupo de realce leptomeníngeo, las etiologías más frecuentes fueron infecciosa (31,7 %), enfermedad metastásica (19,5 %) y neoplasias primarias (17,1 %), persistiendo esta tendencia en el subgrupo de realce paquimeníngeo. En el subgrupo de realce mixto, la etiología posquirúrgica fue la primera causa (35,9 %), seguida de la enfermedad metastásica (23,1 %) y las infecciones (18 %). En los casos de etiología infecciosa se encontró un predominio del patrón de realce leptomeníngeo, nodular y difuso, sin realce paquimeníngeo, como único tipo de realce. Conclusión: Aunque un patrón de realce meníngeo determinado no es indicativo de una patología específica, el estudio detallado de sus características puede aportar información que permite plantear grupos diagnósticos, particularmente en casos de etiología neoplásica o infecciosa, aporte de relevancia en casos en que el realce meníngeo anormal es la única alteración evidente en una resonancia magnética.

Objective: To describe the characteristics of intracranial meningeal enhancement (IME) as magnetic resonance imaging findings and their behavior under different associated conditions as described in the scientific literature. Materials and methods: Descriptive cross-sectional study with data collected from the images archive between January and December of 2011, obtaining 89 eligible studies in which it was determined, in the original reading, presence of IME as positive finding. Each study was subjected to further review by a neuroradiologist of the institution for morphological characterization of the IME. Results: The most common causes of IME were: metastatic disease (21.3%), infectious etiology (21.3%), history of intracranial surgery (20.2%) and primary neoplasms (13.5%). Of total CNS infections (19 cases), HIV infection was documented in 12 patients (70.6%). The patient with the oldest surgical history underwent craniotomy 17 years before performing the MRI included in the study, with persistance of IME with no signs of recurrence defined by image or clinical manifestations up to 2015. The most frequent IME type was leptomeningeal (LME) (46.1%), followed by mixed (MME) (43.8%) and pachymeningeal (PME) (10.1%) enhancements. In the subgroup of LME, the most common etiologies were: infectious (31.7%), metastatic disease (19.5%) and primary neoplasms (17.1%). This trend persisted in the subgroup of PME. In the subgroup of MME, post-surgical etiology was the leading cause (35.9%), followed by metastatic disease (23.1%) and infections etiologies (18%). Conclusion: Although a particular pattern of meningeal enhancement is not indicative of a specific pathology, detailed study of its features can provide information that allow the proposal of diagnostic groups, particularly in cases of neoplastic or infectious etiology, relevant contribution in cases where the abnormal meningeal enhancement is the only anormality in MRI.