Posterior Fossa Mass Lesion Research Articles

An Unusual Case of CNS Tuberculoma in a 19-Year-Old Man

Background: Tuberculosis (TB) is ranked as one of the top 10 causes of death. Mycobacterium tuberculosis (M. TB) infection, the causative organism for TB affects approximately a quarter of the global population placing a burden on the healthcare system. Central nervous system tuberculosis (CNS TB) is seen in 5 to 10% of extrapulmonary TB cases and has the highest mortality. CNS tuberculoma is one of its manifestation. Clinical presentation of CNS tuberculoma depends on its location within the CNS and commonly include headache, seizures, and focal neurological deficits, due to the presence of a space occupying lesion, although patients can be asymptomatic. We report the case of a 19yr old man who had an unusual presentation of CNS tuberculoma, highlighting its clinical presentation, diagnosis and treatment. Case Presentation: Index patient is a 19-year-old male college student who resides in a city. He presented with 15 days history of fever, headache, vomiting, vertigo, ataxia, and inability to concentrate. He received antimalarial, anti typhoid and body booster medications but had no improvement and had a history of weight loss despite no dietary change. He had never been diagnosed with TB and had all his childhood vaccinations given. Plain Magnetic Resonance Imaging (MRI) brain scan done revealed a posterior fossa mass lesion with perilesional edema. Futher, a contrast MRI brain scan showed multiple ring-enhancing conglomerates of lesion around the tentorium on the posterior fossa with intense contrast enhancement. The largest of this mass measured 4.5 cm x 2.5 cm x 2.5 cm in the right superior cerebellum compressing the 4th ventricle and with effacement of the cerebellopontine angle. Lastly, an MRI spectrometry revealed elevated lipid lactate peak. His chest x-ray was unremarkable. Other blood parameters were essentially within range with the exception of Erythrocyte ESR and mantoux test. He received antitubercular drug (Isoniazid, Rifampin, Pyrazinamide, Ethambutol, Levoflox and Streptomycin) for 18th months with complete remission. Conclusion: CNS tuberculomas are tuberculous masses that can be located anywhere from the brain to spinal cord. Advanced diagnostic modalities may guide clinicians towards making it's diagnosis. Treatment maybe medical (use of antitubercular drugs) or surgical excision with medical therapy being first choice. While the index patient had no obvious risk factors for his disease, his BCG vaccination pose a possible source of his exposure to TB infection. More research is needed on this however.

Role of bedside video-oculography in selecting neuroimaging in patients with acute vertigo and ataxia posterior fossa mass lesions

The acute vestibular syndrome ((AVS) is the sudden onset of continuous vertigo, nausea, vomiting and head motion intolerance [1]. The most common peripheral cause is a vestibular neuritis [2], and the most frequent central lesion associated with an AVS is an ischemic stroke in about 10 to 15% of cases [3–5]; less frequently demyelinating plaques (multiple sclerosis (MS) and neuromyelitis optica (NMO)) [6], and inflammatory lesions associated with infectious and paraneoplastic disorders may be responsible.

An anatomical model for studying cerebellar tonsillar herniation related to raised intracranial pressure

Brain herniation is one of the most feared complications of many neurological pathologies. However, current understanding of the mechanisms behind brain herniation syndromes is poor. By investigating the correlations between raised intracranial pressure (ICP) and herniation of the cerebellar tonsils, we hope to develop a model that can be used to study intracranial fluid dynamics and its effects on brain tissue. This will facilitate evaluation of patients with elevated ICP and development of novel treatments including surgical approaches for decompressing the posterior cranial fossa and upper cervical spine. A standard suboccipital surgical approach was used to expose the foramen magnum and observe movements of the cerebellar tonsils in fresh cadavers. A urinary Foley catheter balloon in the parietal extradural space was used to simulate a mass effect while ICP was monitored. The baseline anatomy differed widely among the cadaver specimens. However, and overall, we found that as ICP rises, the cerebellar tonsils descend through the foramen magnum at a rate of 0.3 mm per 1 mmHg increase in ICP. A mean descent of 6.2 mm was observed for a mean ICP increase of 17 mmHg. In this cadaveric study, we present a method and model for exploring brain herniation syndromes in the context of ICP changes. This could allow for further models to study the effects of other neuropathologies on the cerebellar tonsils, including posterior cranial fossa mass lesions and cerebellar hemorrhage.

Ventriculostomy and Risk of Upward Herniation in Patients with Obstructive Hydrocephalus from Posterior Fossa Mass Lesions.

Patients with posterior fossa lesions causing obstructive hydrocephalus present a unique clinical challenge, as relief of hydrocephalus can improve symptoms, but the perceived risk of upward herniation must also be weighed against the risk of worsening or continued hydrocephalus and its consequences. The aim of our study was to evaluate for clinically relevant upward herniation following external ventricular drainage (EVD) in patients with obstructive hydrocephalus due to posterior fossa lesions. We performed a retrospective review of patients undergoing urgent/emergent EVD placement at our institution between 2007 and 2014, evaluating the radiographic and clinical changes following treatment of obstructive hydrocephalus. Even prior to EVD placement, radiographic upward herniation was present in 22 of 25 (88%) patients. The average Glasgow Coma Scale of patients before and after EVD placement was 10 and 11, respectively. Radiographic worsening of upward herniation occurred in two patients, and upward herniation in general persisted in 21 patients. Clinical worsening occurred in two patients (8%), though in all others the clinical examination remained stable (44%) or improved (48%) following EVD placement. Of the patients who had a worsening clinical exam, other variables likely also contributed to their decline, and cerebrospinal fluid diversion was likely not the main factor that prompted the clinical change. Radiographic presence of upward herniation was often present prior to EVD placement. Clinically relevant upward herniation was rare, with only two patients worsening after the procedure, in the presence of other clinical confounders that likely contributed as well.

Using the Physical Examination to Diagnose Patients with Acute Dizziness and Vertigo

BackgroundEmergency department (ED) patients who present with acute dizziness or vertigo can be challenging to diagnose. Roughly half have general medical disorders that are usually apparent from the context, associated symptoms, or initial laboratory tests. The rest include a mix of common inner ear disorders and uncommon neurologic ones, particularly vertebrobasilar strokes or posterior fossa mass lesions. In these latter cases, misdiagnosis can lead to serious adverse consequences for patients. ObjectiveOur aim was to assist emergency physicians to use the physical examination effectively to make a specific diagnosis in patients with acute dizziness or vertigo. DiscussionRecent evidence indicates that the physical examination can help physicians accurately discriminate between benign inner ear conditions and dangerous central ones, enabling correct management of peripheral vestibular disease and avoiding dangerous misdiagnoses of central ones. Patients with the acute vestibular syndrome mostly have vestibular neuritis, but some have stroke. Data suggest that focused eye movement examinations, at least when performed by specialists, are more sensitive for detecting early stroke than brain imaging, including diffusion-weighted magnetic resonance imaging. Patients with the triggered episodic vestibular syndrome mostly have benign paroxysmal positional vertigo (BPPV), but some have posterior fossa mass lesions. Specific positional tests to provoke nystagmus can confirm a BPPV diagnosis at the bedside, enabling immediate curative therapy, or indicate the need for imaging. ConclusionsEmergency physicians can effectively use the physical examination to make a specific diagnosis in patients with acute dizziness or vertigo. They must understand the limitations of brain imaging. This may reduce misdiagnosis of serious central causes of dizziness, including posterior circulation stroke and posterior fossa mass lesions, and improve resource utilization.

Frontal lobe signs after posterior fossa surgery: Is hypoperfusion ignored?

Sir, Behavioral manifestations constitute major burden of patients suffering from brain tumors.[2] Cerebellar mutism syndrome, known to occur following surgery for posterior fossa tumors, is not commonly associated with behavioral symptoms. A 12-year-old boy, diagnosed with posterior fossa mass lesion underwent ventriculoperitoneal shunt followed by definitive surgery. He developed acute mutism symptoms after the surgery and presented with hyperactivity, inattention, and inappropriate social behavior in the form of soiling and urinating in public. Single-photon emission computed tomography was performed 15 days after surgery for these symptoms and it showed cerebral hypoperfusion in right frontal and thalamoganglionic regions [Figure 1]. Figure 1 Brain single-photon emission computed tomography showing moderately reduced perfusion in right inferior orbitofrontal region, right lateral temporal, right thalamic, right basal ganglia, and bilateral occipito-parietal regions (right > left) Altered speech and other manifestations after posterior fossa surgery are often secondary to edema or hypoperfusion adjacent to the surgical trauma.[4] Remote localized deficits after posterior fossa surgery are however not common, though crossed cerebello-cerebral diaschisis due to involvement of dentato-thalamo-cortical pathway has been occasionally reported.[1] Some of these atypical remote presentations were described possibly due to vascular phenomena.[3] However, extensive remote hypoperfusion as described above have not been reported much. Perfusion deficits in these atypical presentations indicate the impact of surgery on brain is more generalized than the operated area similar to the systemic nature of head injury.[4] In addition, perfusion tests may not only help to evaluate patients with atypical postoperative symptoms, but also open up therapeutic avenues as well as for prognosis. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

MB-37 * METACHRONOUS SUPRATENTORIAL INTRACRANIAL MALIGNANT TUMORS IN TWO PEDIATRIC PATIENTS WITH INFRATENTORIAL MEDULLOBLASTOMA ON HORMONE THERAPY

INTRODUCTION: Medulloblastomas are classified by the WHO as embryonal tumors and comprise the most common of the malignant pediatric brain tumors while accounting for twenty percent of all pediatric brain tumors. The phenomenon of second malignancy is uncommonly seen in cases of uniform histology and are more rare when they are of a different histological type. The authors report two cases of infratentorial medulloblastomas that subsequently developed a grade IV glioma in one case, and a second medulloblastoma in the other. PRESENTATION: An eleven year-old female had been experiencing vision difficulty with right eye deviation and emesis. MRI showed a partially-enhancing posterior fossa mass lesion. Four years later, she was discovered to have a right parietal ring-enhancing lesion on routine surveillance. A four year-old female presented to our institution with a one-month history of headaches and emesis and a posterior fossa mass lesion. Three and a half years later, subsequent routine surveillance revealed a new enhancing lesion of the left temporal region with a higher Ki-67 labeling index. TREATMENT: Our first patient underwent sub-occipital craniotomy and gross-total resection for her medulloblatoma followed by chemoradiation under a COG protocol consisting of Vincristine, Cisplatin, and Cyclophosphamide and 23.4 Gy with a posterior fossa boost of 30.6 Gy. She underwent craniotomy for the GBM with GTR followed by maintenance chemotherapy. Our second patient underwent similar therapy with GTR for both lesions then was initiated after the second resection on a COG trial consisting of Bevacizumab, Temodar, and Irinotecan. Of note, both patients were on hormone therapy: GH and Lupron. CONCLUSIONS: We report two cases of infratentorial medulloblastoma with subsequent development of supratentorial lesions with discrepant histological profiles. A second malignancy of different cellular origin is rare, and molecular profiling of the two metachronous medulloblastomas will reveal whether they represent unique entities.

Giant posterior fossa arachnoid cyst causing tonsillar herniation and cervical syringomyelia

Acquired cerebellar tonsillar herniation and syringomyelia associated with posterior fossa mass lesions is an exception rather than the rule. In the present article, we describe the neuroimaging findings in a case of 28-year-old female patient presented with a history of paraesthesia involving right upper limb of 8-month duration. Magnetic resonance imaging showed a giant retrocerebellar arachnoid causing tonsillar herniation with cervical syringomyelia. The findings in the present case supports that the one of the primary mechanism for the development of syringomyelia may be the obstruction to the flow of cerebrospinal fluid causing alterations in the passage of extracellular fluid in the spinal cord and leading to syringomyelia.

Multiple myeloma presenting as solitary mass in the posterior fossa

Intracranial plasma cell tumors are extremely rare and can either be solitary lesions or part of systemic multiple myeloma. We report a 42-year-old woman who presented with a posterior fossa mass and successfully underwent surgical resection, leading to the diagnosis of multiple myeloma. To our knowledge, this is the first reported case of multiple myeloma presenting as a posterior fossa mass lesion. This report highlights the importance of maintaining plasma cell tumor in the differential of intracranial mass with bony involvement. Furthermore, once the diagnosis is established, further work up is critical to evaluate for systemic disease.

Medulloblastoma: atypical CT and MRI findings in children

Posterior fossa mass lesions in children usually present a diagnostic challenge despite their high frequency and the limited number of differential diagnostic possibilities. Consideration of medulloblastoma within the differential diagnosis of such lesions mandates an aggressive surgical approach as residual tumor is a known risk factor for poor prognosis. Preoperative imaging of the entire neuroaxis is critical given the high propensity of drop metastases. In this pictorial presentation, we review and demonstrate less common features of medulloblastomas to facilitate diagnosis in challenging cases.

Lhermitte-Duclos disease with atypical vascularization – case report and review of the literature

A case of Lhermitte-Duclos disease (LDD, dysplastic gangliocytoma) with atypical vascularization is reported. LDD is a rare cerebellar mass lesion which may be associated with Cowden's syndrome and the PTEN germline mutation. A 61-year-old male presented 15 years before with a transient episode of unspecific gait disturbance. Initial magnetic resonance (MR) imaging revealed a right-sided, diffuse, nonenhancing cerebellar mass lesion. No definitive diagnosis was made at that time, and the symptoms resolved spontaneously. 15 years later, the patient presented with acute onset of vomiting associated with headache and ataxic gait. MR imaging showed a progression of the lesion with occlusive hydrocephalus. The lesion depicted a striated pattern characteristic for LDD with T1-hypointense and T2-hyperintense bands, nonenhancing with contrast. After resection of the mass lesion, the cerebellar and hydrocephalic symptoms improved rapidly. The pathological examination confirmed the diagnosis of dysplastic gangliocytoma (WHO Grade I) with enlarged granular and molecular cell layers, reactive gliosis and dysplastic blood vessels. No other clinical features associated with Cowden's syndrome were present. This case illustrates that LDD with atypical vascularization is a slow-growing posterior fossa mass lesion which may remain asymptomatic for many years. Timing of surgical treatment and extent of resection in patients with LDD is controversial. The typical features on standard T1-/T2-weighted MR imaging allow a diagnosis without surgery in most cases. The authors believe that the decision to treat in these cases should be based on clinical deterioration.

Cemento-ossifying fibroma presenting as a posterior fossa mass lesion

Cemento-ossifying fibromas are benign lesions of the jaw, which arise from the periodontal membrane. Histopathologically these are composed of fibrous tissues with calcified structures resembling bone and cementum. Surgical resection is the treatment of choice. They have rarely been reported in the ethmoid sinus, maxillary sinus and sphenoid sinus Mastoid bone is an extremely rare site of such tumors. Only one case of cemento-ossifying fibroma of petromastoid bone has been reported before. We present a case of cementoossifying fibroma involving the petromastoid bone, with the large intracranial component causing compression on the cerebellum. This unique case may provide insight into the etiopathogenesis of these tumors.

Treatment of cerebellar masses

Cerebellar masses are a heterogenous group of conditions that can cause compression of the aqueduct or fourth ventricle, resulting in obstructive hydrocephalus, brainstem compression, and upward/downward herniation as a direct result of mass effect. Untreated lesions can be fatal in a few hours, but prompt and appropriate treatment of the mass effect can produce very good outcomes. These patients should be closely followed in a critical care setting that has rapid access to neurosurgical expertise. Medical measures to decrease brain edema should be taken, including elevation of the head of the bed and avoidance of hypo-osmolar solutions, hypercarbia, or hyperthermia. Osmotic diuretics should be initiated promptly in patients with clinical worsening and radiographic evidence of edema resulting in mass effect. However, medical measures should not delay surgical intervention, which should proceed as rapidly as possible when indicated. Cerebellar hemorrhages more than 3 cm in diameter and cerebellar hemispheric strokes involving more than one third of the hemisphere should be considered for early suboccipital craniotomy with decompression. Regardless of lesion size, neurologic deterioration and radiologic signs of obstructive hydrocephalus should call for emergency decompressive surgery with resection of hematoma or necrotic brain tissue. Ventriculostomy should be considered as a bridge to surgical decompression, given the theoretical concern of upward herniation mediated by supratentorial drainage in the face of an underlying posterior fossa mass lesion. Steroids are not indicated for cerebrovascular disease but should be used to treat vasogenic edema induced by tumor. Anticoagulation is reserved for cerebellar venous and dural sinus thrombosis. Specific treatments targeting the underlying pathology should be used aggressively: thrombolysis and endovascular interventions for eligible stroke patients, antibiotic therapy for abscesses, and radiotherapy, chemotherapy, or both for tumors.

Abscess-a rare fourth ventricular mass

Midline posterior fossa mass lesions in young adults are usually medulloblastomas, pilocytic astrocytomas, haemangioblastomas or ependymomas. We present clinical, imaging and intraoperative findings of an abscess occurring within the fourth ventricle which was associated with right chronic suppurative otitis media and right transverse sinus thrombosis. The possible pathogenesis is discussed.

Primary intracranial squamous cell carcinoma arising in an epidermoid cyst—A case report and review of literature

Primary intracranial squamous cell carcinoma is extremely rare, with most of the cases arising from malignant transformation of an epidermoid or a dermoid cyst. We report here a case of a 45-year-old male patient who presented with 1-month history of intermittent headache and recent onset of altered sensorium. Imaging revealed a midline posterior fossa mass lesion compressing the fourth ventricle and causing hydrocephalus. A provisional diagnosis of dermoid cyst was considered. Histopathological examination revealed a squamous cell carcinoma possibly arising from an underlying epidermoid cyst. This entity is being reported for its rarity.

Surgical Management of Posterior Fossa Mass Lesions

Patients with mass effect on computed tomographic (CT) scan or with neurological dysfunction or deterioration referable to the lesion should undergo operative intervention. Mass effect on CT scan is defined as distortion, dislocation, or obliteration of the fourth ventricle; compression or loss of visualization of the basal cisterns, or the presence of obstructive hydrocephalus. Patients with lesions and no significant mass effect on CT scan and without signs of neurological dysfunction may be managed by close observation and serial imaging. In patients with indications for surgical intervention, evacuation should be performed as soon as possible because these patients can deteriorate rapidly, thus, worsening their prognosis. Suboccipital craniectomy is the predominant method reported for evacuation of posterior fossa mass lesions, and is therefore recommended.

Management of Traumatic Brain Injury

In the past years several recommendations have been published concerning the diagnostic work-up and treatment of patients with traumatic brain injury (TBI). They show that with regard to the surgical management of acute epidural hematomas, acute subdural hematomas, traumatic parenchymal lesions, posterior fossa mass lesions, as well as depressed skull fractures there is a lack of controlled studies, which would allow to define standards of treatment or guidelines, respectively. Nonetheless, treatment protocols serve an important purpose, because they may improve management of TBI patients by promoting uniform decision-making in the treatment of these patients, namely in • the identification of the few patients likely to suffer from complications among the large number of patients who sustain a mild to moderate head injury and • strategies for avoiding posttraumatic cerebral ischemia. In this context, the authors focus on the importance of plain skull X-rays and CT scan, respectively, in the work-up of mild TBI patients and on the indications for decompressive craniectomy for the relief of intractable elevation of intracranial pressure following severe TBI.

Management strategies for treatment of the trapped fourth ventricle.

An isolated or trapped fourth ventricle (TFV) is an occasional, serious sequela of hemorrhagic, infectious, or inflammatory conditions of the central nervous system. The TFV usually occurs after successful shunting of the lateral ventricles. It may be heralded by delayed clinical deterioration after an initial period of symptomatic improvement. The typical clinical findings suggest an expanding posterior fossa mass lesion. Surgical treatments include CSF diversionary procedures as well as open and endoscopic approaches. Complications related to the treatment of the TFV are common and relate to catheter obstruction and cranial nerve or brainstem dysfunction. The author reviews the clinical features, pathophysiology, and available treatment options for the TFV, with special reference to complication avoidance and advances in ventriculoscopy and frameless stereotaxy. Treatment of the TFV remains a formidable challenge. However, prompt recognition and intervention may aid in the preservation of life and neurological function.

CT stereotaxy guided lateral trans-cerebellar programmable fourth ventriculo–peritoneal shunting for symptomatic trapped fourth ventricle

A trapped fourth ventricle is a rare clinico-radiological entity producing symptoms suggestive of a progressive posterior fossa mass lesion. It is mainly reported in children as a late complication of lateral ventricular shunting to relieve infantile post-meningitic or post-hemorrhagic hydrocephalus. Optional treatment of the trapped fourth ventricle remains controversial. Placement of fourth ventricular shunting via a conventional midline approach can be fraught with complications in about 40% of the patients. Authors report a successful CT Stereotaxy guided high pressure (80 mm H 2O) programmable fourth ventriculo–peritoneal shunting via a lateral trans-cerebellar approach in a 14-year-old girl with a trapped fourth ventricle, which occurred as a late complication of ventriculo-peritoneal shunting in her infancy. Her preoperative symptoms of raised intracranial pressure, bobble-head doll syndrome and bilateral abducens palsies completely improved following the surgery. Lateral trans-cerebellar stereotactic placement of the fourth ventricular catheter and the use of high-pressure (low flow) programmable shunt (to avoid complications associated with over drainage) are beneficial in some patients with trapped fourth ventricle.

Mutism and Pseudobulbar Symptoms after Resection of Posterior Fossa Tumors in Children

MUTISM AND A variety of other neurobehavioral symptoms have been reported anecdotally after the removal of posterior fossa mass lesions. To determine the incidence and clinical spectrum of this syndrome, a detailed review was performed of patients undergoing resection of infratentorial tumors at our institution during the last 9 years; 12 of 142 patients (8.5%) manifested this syndrome, the largest series of such patients reported to date. Each child had a lesion that involved the vermis; seven had medulloblastomas, three had astrocytomas, and two had ependymomas. The incidence among children with vermian neoplasms was 13%. Ten children underwent division of the inferior vermis during tumor resection, and three had a superior vermian incision; one child underwent both superior and inferior vermian incisions. In 10 children, mutism developed in a delayed fashion postoperatively. The speech disturbance was associated with poor oral intake in 9 children, urinary retention in 5, long-tract signs in 6, and bizarre personality changes, emotional lability, and/or decreased initiation of voluntary movements in all 12. Neuropsychiatric testing, performed in seven children, confirmed impairments not only in speech but also in initiation of other motor activities. Ten children regained normal speech, bladder control, and neurological functioning, other than ataxia and mild dysarthria, within 1 to 16 weeks; two children had significant residual deficits. Characteristically, affect and oral intake returned to their preoperative baseline before the speech difficulties began to resolve. A detailed radiological review of these cases in parallel with 24 cases of vermian tumors without mutism identified only one factor that was significantly associated with the mutism syndrome, bilateral edema within the brachium pontis (P < 0.01). Neither the size of the tumor nor the length of vermian incision was associated with the development of mutism. The clinical features of this syndrome in the context of these imaging findings suggest that the mutism syndrome results from transient impairment of the afferent and/or efferent pathways of the dendate nuclei that are involved in initiating complex volitional movements. The clinical courses of our patients are presented and compared with those of similar cases in the literature in an attempt to evaluate the validity of this hypothesis.