The Role of Aquaporin 1 in Water Retention Mechanism of Arachnoid Cysts: Insights from 3 Case Reports.

BACKGROUND Although arachnoid cysts are common lesions, the pathogenesis of their continuous growth remains unclear. We aimed to identify the role of aquaporins in arachnoid cyst specimens. CASE REPORT We selected 3 cases from our own facility and examined arachnoid cyst wall specimens, which were sampled intraoperatively. Patients presented with variable symptoms, a 52-year-old man with a "heavy sensation" in the head and dysesthesia on the left hand, a 68-year-old man with unsteady gait, and finally a 26-year-old woman with a history of intermittent headaches for 10 years. Intraoperative specimens were obtained and examined. Evaluation techniques were light microscopy, immunohistochemical staining for aquaporin, and electron microscopy. Light microscopy showed that cells were arranged in epithelium-like structures forming several thick lamellae, with visible connective tissue among them. Under electron microscopic examination, cells with many or few cell organelles and with spindle-like nuclei were arranged in lamellar or flattened structures. Many vacuolizations were seen in between. Interdigitation of cells and many desmosomes were observed. All 3 cases were positive for aquaporin 1. CONCLUSIONS Our study showed that water transportation through aquaporin 1 has a potential role in the formation and expansion of arachnoid cysts.

How to understand an enlarged Meckel's cave? An anatomical study.

PURPOSE: Dilatation of the trigeminal cavum, or Meckel's cave (MC), is usually considered a radiological sign of idiopathic intracranial hypertension. However, the normal size of the trigeminal cavum is poorly characterized. In this study, we describe the anatomy of this meningeal structure. METHODS: We dissected 18 MCs and measured the length and width of the arachnoid web and its extension along the trigeminal nerve. RESULTS: Arachnoid cysts were clearly attached to the ophthalmic (V1) and maxillary (V2) branches until they entered the cavernous sinus and foramen rotundum, respectively, without extension to the skull base. Arachnoid cysts were close to the mandibular branch toward the foramen ovale, with a median anteromedial extension of 2.5 [2.0-3.0] mm, lateral extension of 4.5 [3.0-6.0] mm, and posterior extension of 4.0 [3.2-6.0] mm. The trigeminal cavum arachnoid had a total width of 20.0 [17.5-25.0] mm and length of 24.5 [22.5-29.0] mm. CONCLUSION: Our anatomical study revealed variable arachnoid extension, which may explain the variability in size of the trigeminal cavum in images and calls into question the value of this structure as a sign of idiopathic intracranial hypertension. The arachnoid web extends beyond the limits described previously, reaching almost double the radiological size of the cavum, particularly at the level of V3 afference of the trigeminal nerve. It is possible that strong adhesion of the arachnoid to the nerve elements prevents the formation of a true subarachnoid space that can be visualized by magnetic resonance imaging.

Intracranial cysts: incidental or neurodevelopmental?

OBJECTIVES: Intracranial cysts are fluid-filled sacs within the brain. There is a diversity of intracranial cysts with different incidences in addition to the growing awareness about comorbidities and the consequences. The present study aimed to evaluate cystic findings in children who were admitted to the department of pediatric neurology. METHODS: Children who were admitted to the Clinic of Pediatric Neurology and who had an MRI between 2016 and 2021 were evaluated. The MRI examination was performed with the pediatric epilepsy protocol. Children with primary intracranial cysts were enrolled in the study. Demographic and clinical findings were evaluated from the hospital's database and patients' files. RESULTS: Among the 78 patients, 36 (46.2%) were male and 42 (53.8%) were female. The mean age was 7 ± 5.4 years. The most frequent presenting complaint was a seizure (47.4%). Approximately one-quarter (28.2%) had mental and/or motor retardation. Nine (11.5%) of the children had a neuropsychiatric diagnosis. Most of the cysts were located at the midline (41%) with the majority located extra-axial (71.8%) and supratentorial (78.2%). Arachnoid cysts were observed most frequently with a percentage of 64.1%, followed by pineal cysts (15.4%). The history of seizure, epilepsy, presence of mental retardation, and neuropsychiatric problems were evaluated according to the population ratios based on z approximation in which significantly higher rates were observed among cases with intracranial cysts. CONCLUSION: Intracranial cysts should be taken into consideration for comorbid pathologies, especially in the childhood period. Early evaluation in patients with intracranial cysts for developmental delay and neuropsychiatric problems is important.

Familial and syndromic forms of arachnoid cyst implicate genetic factors in disease pathogenesis.

Arachnoid cysts (ACs) are the most common space-occupying lesions in the human brain and present significant challenges for clinical management. While most cases of ACs are sporadic, nearly 40 familial forms have been reported. Moreover, ACs are seen with increased frequency in multiple Mendelian syndromes, including Chudley-McCullough syndrome, acrocallosal syndrome, and autosomal recessive primary ciliary dyskinesia. These findings suggest that genetic factors contribute to AC pathogenesis. However, traditional linkage and segregation approaches have been limited in their ability to identify causative genes for ACs because the disease is genetically heterogeneous and often presents asymptomatically and sporadically. Here, we comprehensively review theories of AC pathogenesis, the genetic evidence for AC formation, and discuss a different approach to AC genomics that could help elucidate this perplexing lesion and shed light on the associated neurodevelopmental phenotypes seen in a significant subset of these patients.

[Symptomatic arachnoid cyst in an elderly patient who developed motor aphasia].

The patient was an 83-year-old woman with a history of breast cancer, distal right radial edge bone fracture, and cervical spine symptoms who had been diagnosed with an arachnoid cyst 9 years previously. She was examined by a nearby doctor, because of an approximately 1-year history of reduced verbal output; she also begun experiencing difficulties with walking. However, she was diagnosed with aging, a history of cervical spondylosis, and the effects of past fractures.At the time of this consultation, she was conscious and lucid, with mild right-sided hemiparesis, was unable to write, and had mild motor aphasia. Head magnetic resonance imaging revealed an arachnoid cyst (longer axis: 10 cm) in the left frontal lobe that did not take up contrast media. There was also a midline shift. The cause of the right hemiparesis and motor aphasia was probably compression of the left frontal lobe by the arachnoid cyst.We performed excision of the cyst wall by craniotomy and placed a cyst-peritoneal shunt under general anesthesia. At approximately one week after surgery, the patient was able to write and her motor aphasia improved. She was discharged 20 days after the operation.It is rare for an arachnoid cyst to increase in size after childhood. In the present case, surgical treatment led to a good outcome in an elderly patient with a symptomatic arachnoid cyst. Arachnoid cysts rarely increase in size. These cysts may become symptomatic in elderly people after lying clinically dormant for a long time.

Optic nerve ultrasonography in the evaluation of the relationship between arachnoid cyst and headache.

AIM: This study is aimed to show the difference between optic nerve sheath diameter (ONSD) values in migraine patients with and without arachnoid cysts from migraine patients and control groups, and to evaluate the relationship with the arachnoid cyst size on magnetic resonance imaging (MRI) and their clinical severity. METHODS: This cross-sectional study included pediatric patients who were previously diagnosed with migraine and the control group. The patients consist of 3 groups. The first group was 24 patients with arachnoid cysts on brain magnetic resonance imaging (MRI) who met the diagnostic criteria for migraine (group 1); the second group was 20 patients with only headache without arachnoid cysts or other findings on brain magnetic resonance imaging (MRI) (group 2); the third group was completely healthy 20 control group. Demographic data of the patients, the onset of headache time, clinical severity, electroencephalography (EEG) findings, optic nerve sheath diameter (ONSD) measurements by ultrasonography, and the volume of arachnoid cyst on brain MRI were determined and compared. RESULTS: The optic nerve sheath diameter (ONSD) value was the highest in group 1 and the lowest in the control group (p: 0.001). The clinical severity was statistically different between the groups (p: 0.038). Accordingly, the majority of the clinical severity of group 1 was determined in grades 3 and 4. A weak positive correlation was found between the arachnoid cyst size on MRI and the ONSD measurement (r = 0.410, p = 0.047). The ONSD value statistically significantly increased with clinical severity in group 1 (p: 0.003). CONCLUSION: The reliability of the optic nerve sheath diameter (ONSD) measurements in determining the increase of the intracranial pressure was shown in previous studies. This is the first study in the literature presenting that the intracranial pressure effects of arachnoid cysts can be demonstrated by ONSD. We have considered that arachnoid cysts detected in headaches can create a compression effect and cause the pain to intensify.

Incidental Intracranial Cysts in Children.

With increasing use of intracranial imaging, the diagnosis of benign intracranial cysts is becoming more frequent in the pediatric population. These lesions are usually incidentally discovered during the work-up of unrelated symptoms. Most do not require treatment and many do not even require imaging follow-up. When symptomatic, symptoms of these lesions are usually caused by local mass effect. Symptomatic lesions warrant neurosurgical evaluation, and may require surgical intervention in rare, well-selected cases. This article describes three common benign intracranial cysts found in the pediatric population: arachnoid cysts, choroid cysts, and pineal cysts.

Intradural Spinal Arachnoid Cyst in a Pediatric Patient: A Case Report

The present case reports a 13-year-old patient with an intradural arachnoid cyst, which manifested itself with a sudden loss of strength and sensitivity in the lower and upper limbs and a severe pain in the cervical and thoracic region. On examination, a lesion displayed as an intradural hematoma; however, a laminotomy was performed and it was realized that the lesion was an arachnoid spinal cyst of the cervical-dorsal spine.

Resolution of the large middle fossa arachnoid cyst without any identifiable cause: Case report.

Although the possibility of spontaneous regression of intracranial arachnoid cysts (AC) during observational follow-up is widely recognized, the number of reports documenting such clinical course, often associated with the mild head trauma, is rather limited. We present a case of nearly complete resolution of the large middle fossa AC in a 5-year-old boy without any identifiable cause in 2.3 years after the initial diagnosis. It once again justifies observational strategy for AC not accompanying by mass effect and manifesting with minimal symptoms or diagnosed incidentally.

Space-occupying brain lesions, trauma-related tau astrogliopathy, and ARTAG: a report of two cases and a literature review.

Astrocytes with intracellular accumulations of misfolded phosphorylated tau protein have been observed in advanced-stage chronic traumatic encephalopathy (CTE) and in other neurodegenerative conditions. There is a growing awareness that astrocytic tau inclusions are also relatively common in the brains of persons over 70 years of age-affecting approximately one-third of autopsied individuals. The pathologic hallmarks of aging-related tau astrogliopathy (ARTAG) include phosphorylated tau protein within thorn-shaped astrocytes (TSA) in subpial, subependymal, perivascular, and white matter regions, whereas granular-fuzzy astrocytes are often seen in gray matter. CTE and ARTAG share molecular and histopathologic characteristics, suggesting that trauma-related mechanism(s) may predispose to the development of tau astrogliopathy. There are presently few experimental systems to study the pathobiology of astrocytic-tau aggregation, but human studies have made recent progress. For example, leucotomy (also referred to as lobotomy) is associated with a localized ARTAG-like neuropathology decades after the surgical brain injury, suggesting that chronic brain injury of any type may predispose to later life ARTAG. To examine this idea in a different context, we report clinical and pathologic features of two middle-aged men who came to autopsy with large (> 6 cm in greatest dimension) arachnoid cysts that had physically displaced and injured the subjects' left temporal lobes through chronic mechanical stress. Despite the similarity of the size and location of the arachnoid cysts, these individuals had dissimilar neurologic outcomes and neuropathologic findings. We review the evidence for ARTAG in response to brain injury, and discuss how the location and molecular properties of astroglial tau inclusions might alter the physiology of resident astrocytes. These cases and literature review point toward possible mechanism(s) of tau aggregation in astrocytes in response to chronic brain trauma.

Paediatric arachnoid cysts: Surgical outcomes from a Singapore children's hospital.

Arachnoid cysts (AC) are reported to have a prevalence of up to 2.6% in children. Most AC remain indolent, but others may expand or rupture to cause life-threatening symptoms of raised intracranial pressure. Currently, there are 2 controversial topics with regards to the management of ACs: the indications for surgery and the choice of surgical procedure. We therein report our institution's neurosurgical experience for symptomatic AC over a 22-year period and corroborate our results with published literature. This is a single institution, retrospective study conducted at KK Women's and Children's Hospital from 01 January 1998 to 31 December 2019. A total of 38 patients with ACs that required surgery were recruited. The 3 most common anatomical locations were in the middle cranial fossa (40.5%), posterior fossa (24.3%) and interhemispheric (13.5%). Typical clinical presentations included symptoms of raised intracranial pressure (34.2%), obstructive hydrocephalus (28.9%) and AC rupture (21.1%). Surgical approaches included 17 craniotomy-based procedures, 7 endoscopic fenestrations, 11 cystoperitoneal shunts, 2 burrhole drainage operations and 1 excision of spinal AC. Thirteen patients (34.2%) underwent either another operation due to the lack of resolution of their AC-related symptoms or secondary to complications directly related to their initial surgery. Average length of followup from time of first operation was 84.1 months. Overall, our results demonstrate similarities in epidemiology, clinical presentation and surgical experience, in comparison to larger cohort studies. We advocate collaborative efforts to better understanding of the pathophysiology of paediatric ACs, particularly for deciding between the various surgical treatment modalities.

Chudley-McCullough Syndrome: A Recognizable Clinical Entity Characterized by Deafness and Typical Brain Malformations.

Chudley-McCullough syndrome, a rare autosomal recessive disorder due to pathogenic variants in the GPSM2 (G-protein signaling modulator 2) gene, is characterized by early-onset sensorineural deafness and a typical combination of brain malformations, including ventriculomegaly, (partial) agenesis of the corpus callosum, cerebellar dysplasia, arachnoid cysts, frontal subcortical heterotopia, and midline polymicrogyria. When hearing loss is managed early, most patients have minor or no impairment of motor and cognitive development, despite the presence of brain malformations. We report 2 cases of Chudley-McCullough syndrome, one presenting with congenital deafness and normal development except for speech delay and one presenting prenatally with ventriculomegaly and an atypical postnatal course characterized by epileptic spasms, deafness, and moderate intellectual disability. These highlight the challenges faced by clinicians when predicting prognosis based on pre- or postnatal imaging of brain malformations. We have also reviewed the phenotype and genotype of previous published cases to better understand Chudley-McCullough syndrome.

Endoscopic treatment of suprasellar arachnoid cysts indenting third ventricle with obstructive hydrocephalus in children: Thirteen cases.

AIMS: The present study aimed to evaluate the clinical usefulness of endoscopic treatment of suprasellar arachnoid cysts indenting the third ventricle with obstructive hydrocephalus and discuss the clinical features and outcomes of thirteen children treated at our institution. METHOD: We treated thirteen pediatric cases of suprasellar arachnoid cysts indenting the third ventricle with obstructive hydrocephalus between January 2012 and September 2018. Five female and eight male patients were enrolled in the study. The patients had increased intracranial pressure symptoms due to hydrocephaly. Endoscopic treatment was performed in all cases. RESULTS: The patients were followed-up for an average of 36.8 months. The postoperative intracranial pressure findings improved. There was a reduction in the size of the cyst and ventricles and enlargement of the cortical sulci. One patient suffered transient oculomotor nerve deficit. No further surgical interventions, such as shunt placement, were required during the follow-up period. The head circumference of two of the patients with macrocephaly were stable during the follow-up. There were no postoperative recurrences detected. CONCLUSIONS: Endoscopic cyst fenestration and third ventriculostomy are less invasive, safer, and more effective ways to treat suprasellar arachnoid cysts indenting the third ventricle with obstructive hydrocephalus in children with hydrocephaly.

Recurrent Spinal Intramedullary Arachnoid Cyst: Case Report and Literature Review.

BACKGROUND: Symptomatic intramedullary arachnoid cysts are rarely observed lesions, particularly in the pediatric age group. Treatment includes cyst fenestration or resection of the cyst wall, and recurrence after surgery has never been reported. We report a rare case of a spinal intramedullary arachnoid cyst, which recurred after cyst fenestration and required reoperation after a certain period. CASE DESCRIPTION: A 4-year-old boy presented to our hospital with tetraparesis and bladder and rectum disorder. A cystic intramedullary lesion in the cervical spinal cord was detected in preoperative imaging. An emergency fenestration of cyst was performed, and his symptoms were resolved immediately. One month after the operation, the symptoms and cyst recurred. The symptoms improved in the natural course without reoperation. However, the cyst increased in size and the symptoms recurred after 27 months from the first relapse and the cyst was removed urgently. The diagnosis was an arachnoid cyst. After the reoperation, the cyst has disappeared and not recurred. CONCLUSIONS: To the best of our knowledge, this is the first report of recurrence of an intramedullary arachnoid cyst. This case indicates the importance of considering the resection of cyst wall as possible because of the probability of cyst recurrence after fenestration, while careful observation is the option in the short term, especially for children or high-risk cases.

Low-grade developmental and epilepsy associated brain tumors: a critical update 2020.

Brain tumors represent the second most frequent etiology in patients with focal seizure onset before 18 years of age and submitted to epilepsy surgery. Hence, this category of brain tumors, herein defined as low-grade, developmental, epilepsy-associated brain tumors (LEAT) is different from those frequently encountered in adults as (A): 77% of LEAT occur in the temporal lobe; (B): the vast majority of LEAT are of low malignancy and classified as WHO I°; (C): LEAT are often composed of mixed glial and neuronal cell components and present with variable growth patterns including small cysts or nodules; (D): LEAT do not share common gene driving mutations, such as IDH1 or 1p/19q co-deletions. Characteristic entities comprise the ganglioglioma (GG), the dysembryoplastic neuroepithelial tumor (DNT), the angiocentric glioma (AG), the isomorphic diffuse glioma (IDG) and the papillary glio-neuronal tumor (PGNT), representing 73.2% of 1680 tumors collected in a large German series of 6747 patients submitted to epilepsy surgery. In the realm of exciting discoveries of genetic drivers of brain tumors new genes have been also reported for LEAT. BRAF V600E mutations were linked to GG with CD34 expression, FGFR1 mutations to DNT, MYB alterations to AG and also IDG and PRKCA fusions to PGNT, suggesting the possibility to also develop a genetically driven tumor classification scheme for LEAT. Rare availability of LEAT in a single center is a challenging obstacle, however, to systematically unravel the neurobiological nature and clinical behavior of LEAT. Other challenges in need of clarification include malignant tumor progression of LEAT entities, seizure relapse in patients following bulk tumor resection and the controversial issue of associated focal cortical dysplasia as additional pathomechanism. In order to advance our understanding and promote reliable diagnostic work-up of LEAT, we recommend, therefore, international collaboration to achieve our goals.

Diagnostic Dilemma in Discriminating Between Spinal Neurenteric Cysts and Simple Arachnoid Cysts Based on Embryogenesis and Surgical Correlation.

BACKGROUND: Neurenteric cyst (NEC) is a rare intradural spinal tumor, but a correct preoperative diagnosis remains challenging. A misdiagnosis of arachnoid cyst (AC) often leads to conflicting surgical management and significantly higher recurrence. CASE DESCRIPTION: We report the case of a 26-year-old woman who presented with progressive spastic quadriparesis with myelopathy below the C4 level, which was caused by a ventral intradural extramedullary cystic tumor at the C3-4 level. Magnetic resonance images showed the cystic content as identical to cerebrospinal fluid, which prompted the tentative diagnosis of spinal AC. Surgical fenestration was scheduled. However, intraoperative findings of a thick-walled cyst and severe adhesion to the neural structure without a history of trauma and inflammation were more compatible with the pathogenesis of an NEC. Because of the high recurrence rate after an incomplete resection of an NEC, we did a complete resection of the cyst with adhesive rootlets instead. Pathology analysis and immunohistochemical staining confirmed the diagnosis of an endodermal-derived NEC. CONCLUSIONS: NECs must be differentiated from ACs because they are different diseases and require different surgical management. In cases with clear cystic content, however, the diagnosis is likely to be AC, but a thick cystic wall and structural adhesions should suggest the differential diagnosis of NEC. Gross total removal of NECs should be attempted to reduce NEC recurrence.

True Dural Spinal Epidural Cysts: Report of 5 Cases.

BACKGROUND: Spinal arachnoid cysts are a rare cause of compressive myelopathy. Spinal extradural arachnoid cysts (SEACs) are even rarer. METHODS: We retrospectively reviewed the SEACs operated on in our hospital between 2015 and 2019, according to their clinical and radiologic findings, treatments performed, and outcomes. RESULTS: We identified 5 cases (2 males and 3 females), ranging in age from 21 months to 78 years. Except for the pediatric case, all patients presented with pain and 3 had some grade of neurologic impairment. Preoperative magnetic resonance imaging showed multiloculated cyst in 4 cases, and the communication with the dura was properly identified in only 1 case. The patients were operated through a laminectomy or laminoplasty and total removal of the cyst, and the communication with the dura was identified and repaired in all cases. In all cases, the defect was near the exit of a nerve root, and rootlets were seen through it, producing a ball-like valve mechanism. Histology of the cyst wall showed true dura in every case. One patient needed a reoperation for evacuation of a fluid collection (related to the dural sealant). Following Odom's criteria, 3 patients had an excellent outcome and 2 had a fair outcome. CONCLUSIONS: Total excision of a symptomatic SEAC through either laminectomy or laminoplasty is a safe and effective treatment option. Although isolated repair of the dural communication without cyst removal may seem appealing, we have found it very difficult to identify the point of communication preoperatively.

When the brain looks imperfect: An example of neuroplasticity as seen in a patient with arachnoid cysts - a case study.

Objective: This study presents a case of a teenager (J.J.) prenatally diagnosed with large arachnoid cysts which did not allow parts of his brain to develop correctly. It aims to establish whether the congenital malformation affected the boy's cognitive development.Method: In order to assess his cognitive development, the authors analyzed J.J.'s medical history, interviewed him and his parents and conducted neuropsychological examination.Results: Despite major parts of his brain undeveloped, the boy achieved average to outstanding scores in all tests.Conclusions: The scores achieved by J.J. suggest that normal development of cognitive abilities is possible even for a person whose central nervous system differs structurally from what is expected in a healthy subject.

Volume change of cranial arachnoid cysts after successful endoscopic fenestration in symptomatic children.

INTRODUCTION: Endoscopic fenestration remains a first-line treatment option for symptomatic arachnoid cysts. After fenestration, the cyst does not collapse but reaches an equilibrium state. The aim of this study was to evaluate the change in cyst volume following successful fenestration and symptomatic improvement. METHODS: Cyst volume was measured on serial MR scans of 4 children (1 female, 3 males) with symptomatic arachnoid cysts (middle fossa n = 2, choroidal fissure n = 1 and posterior fossa n = 1), who experienced symptom resolution after endoscopic fenestration. Average follow-up was 20.5 months (range 3-48). RESULTS: Significant cyst volume reduction was seen in all four patients. In patient 1, preoperative cyst volume was 336 cm3 and decreased to 194 cm3 at 7 months (42% reduction). In patient 2, preoperative volume was 12.64 cm3 and reduced to 1.51 cm3 at 3 months (88% reduction). In patient 3, preoperative volume was 105 cm3 and reduced to 72 cm3 in 2 months (30% reduction). In patient 4, preoperative volume was 125 cm3 and reduced to 54 cm3 at 7 months (56% reduction). All remained stable after 7 months and there has been no late increase in volume. CONCLUSIONS: Significant reduction in arachnoid cyst volume at the order of 30-40% is seen after successful endoscopic fenestration. The cyst volume appears to decrease gradually in the first 3-7 months and reaches a plateau after that. Complete resolution of symptoms in the presence of residual volume may indicate that cyst volume below a threshold may not correlate directly with clinical status.