Intracanalicular optic nerve meningioma: a serious diagnostic pitfall

We describe six cases of cannalicular optic nerve meningioma in which the diagnosis was missed for more than 1 year after the onset of symptoms. Clinical features led to a misdiagnosis of optic neuritis in all cases. Although atypical clinical progression led to further imaging studies, they did not provide the diagnosis because of inappropriate imaging protocols. Diagnosis was eventually made on the basis of high-spatial-resolution contrast-enhanced MR findings. Radiologists should have a high suspicion for the diagnosis of optic canal meningioma in patients with unexplained visual loss, particularly when visual loss is progressive. Investigation in these cases should include high-spatial-resolution MR imaging of the orbit before and after contrast medium administration, and fat suppression should be used in combination with contrast enhancement whenever possible.     

Intratumoral microhemorrhages on T2*-weighted gradient-echo imaging helps differentiate vestibular schwannoma from meningioma

BACKGROUND AND PURPOSE: Vestibular schwannomas (VS) may be difficult to differentiate from cerebellopontine angle (CPA) meningiomas. Demonstration of microhemorrhages in VS on T2*-weighted gradient-echo (GRE) sequences may have potential value to differentiate VS from CPA meningiomas.Materials and METHODS: In this prospective study of 20 patients, MR imaging was performed with T2*-weighted GRE in addition to all basic sequences. Histopathologic examination was performed after surgery. Intratumoral hemosiderin was confirmed by pigment staining.RESULTS: There were 15 patients in the VS group with 16 VS and 5 in the meningioma group with 5 posterior fossa meningiomas. Fourteen of the 16 VS and all 5 meningiomas were treated surgically and were confirmed on histopathologic examination. T2*-weighted GRE identified microhemorrhages on T2*-weighted sequence in 15 (93.75%) of the 16 VS. CT excluded calcification in all VS. T2-weighted turbo spin-echo (TSE) and fluid-attenuated inversion recovery (FLAIR) images recognized microhemorrhages in 2 cases. Pigment staining confirmed hemosiderin in all 14 surgically treated VS, and none of the meningiomas showed microhemorrhages on MR imaging. For the detection of microhemorrhages, T2*-weighted GRE showed a sensitivity of 93.8%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 83.3%. The sensitivity of T2 TSE and FLAIR for microhemorrhage was 12.5%. The Fisher exact test showed a statistically significant difference in the differentiation of VS from meningioma on the basis of detection of microhemorrhages (P < .01).CONCLUSION: Most VS demonstrate microhemorrhages on T2*-weighted GRE. This finding is useful to differentiate VS from CPA meningiomas. T2*-weighted GRE should be used as a basic sequence to evaluate CPA tumors. Identification of microhemorrhages may have the potential to assess the aggressive biologic behavior of VS.

Vestibular schwannomas (VS) and meningiomas comprise most cerebellopontine angle (CPA) tumors. VS constitute 80% to 90% and meningiomas 10% to 15% of CPA tumors.¹ It is essential to distinguish these 2 lesions accurately before surgery because the outcome with preservation of hearing is better with meningiomas.¹ MR imaging is considered the imaging method of choice to assess CPA tumors and to distinguish VS from meningiomas. A tumor in the internal auditory canal (IAC) with dilation of the canal is highly suggestive of VS. Signs such as the presence of hyperostosis, calcification, broad base of the tumor against the tentorium, and a dural tail may favor the diagnosis of a meningioma.² However, both VS and meningioma may show similar imaging features, and hence it is not surprising that approximately 25% of CPA meningiomas are mistaken for VS.³ Identification of microhemorrhages may be of interest to assess its relationship to the development of cystic changes in VS and to identify cases at risk of developing clinically significant intratumoral bleed. To our knowledge, no previous study has been done with T2*-weighted gradient-echo (GRE) sequence to assess the presence of intratumoral microhemorrhages and its diagnostic potential in identifying VS.     

Intracanalicular arachnoid cyst mimicking acoustic neuroma: CT and MRI.

A patient with a surgically proven intracanalicular arachnoid cyst was studied using computed tomography, magnetic resonance imaging, and air CT cisternography. The lesion had a similar radiographic appearance to acoustic neuroma and therefore, although rare, must be considered in the differential diagnosis of intracanalicular mass lesions. We report a case in which examination was performed, in evaluating the lesion, utilizing high-resolution air CT cisternography and magnetic resonance imaging (MRI).     

Stereotactic radiotherapy of vestibular schwannoma

Objective

The aim of this publication is to present long-term data on functional outcomes and tumor control in a cohort of 107 patients treated with stereotactic radiotherapy (RT) for vestibular schwannoma.

Patients and methods

Included were 107 patients with vestibular schwannoma (primary or recurrent following resection) treated with stereotactic RT (either fractioned or single-dose radiosurgery) between October 2002 and December 2013. Local control and functional outcomes were determined. Analysis of hearing preservation was limited to a subgroup of patients with complete audiometric data collected before treatment and during follow-up. Vestibular function test (FVT) results could be analyzed in a subset of patients and were compared to patient-reported dizziness.

Results

After a mean follow-up of 46.3 months, actuarial local control for the whole cohort was 100% after 2, 97.6% after 5, and 94.1% after 10 years. In patients with primary RT, serviceable hearing was preserved in 72%. Predictors for preservation of serviceable hearing in multivariate analysis were time of follow-up (odds ratio, OR = 0.93 per month; p = 0.021) and pre-RT tumor size (Koos stage I–IIa vs. IIb–IV; OR = 0.15; p = 0.031). Worsening of FVT results was recorded in 17.6% (N = 3). Profound discrepancy of patient-reported dizziness and FVT results was observed after RT. In patients with primary RT, worsening of facial nerve function occurred in 1.7% (N = 1).

Conclusion

Stereotactic RT of vestibular schwannoma provides good functional outcomes and high control rates. Dependence of hearing preservation on time of follow-up and initial tumor stage has to be considered.

     

Flow ghost artifact in slice-encoding direction mimicking vestibular schwannoma in contrast-enhanced 3D spoiled gradient-echo sequence

The value of MR imaging by post-contrast T1-weighted 3D spoiled gradient-echo (3D SPGR) is well established for the detection of small vestibular schwannomas in the cerebellopontine angle region. We describe a case in which a flow ghost artifact in the slice-encoding direction mimicked a vestibular schwannoma and heavily T2-weighted MR cisternography and multiplanar reconstruction images helped us to reach the correct diagnosis. In addition, we conducted a volunteer study to demonstrate that changing the k-space trajectory can reduce this artifact in post-contrast 3D SPGR images.     

Cystic schwannoma mimicking adrenal tumor

The CT and ultrasound findings in a case of cystic schwannoma mimicking a left adrenal tumor are reported. The differential diagnosis of cystic lesions arising in the adrenal region is discussed.     

Primary cranial vault lymphoma mimicking meningioma

Primary lymphomas of the cranial vault are rare; only six patients have been described in the literature. We report a 75-year-old woman who was admitted to our hospital after a focal seizure. CT showed a homogeneous mass which, on contrast enhancement, was similar to a meningioma. The tumour was excised and found to be a centroblastic, centrocytic non-Hodgkin's lymphoma. Treatment was completed with radiotherapy and chemotherapy.     

Cerebellopontine angle pilocytic astrocytoma mimicking acoustic schwannoma

We describe a case of pilocytic astrocytoma of the cerebellum mimicking an acoustic schwannoma. The tumour protruded into the porus acusticus and enlarged the internal auditory meatus, which is a quite unusual characteristic of glial tumours. Received: 2 February 1999 Accepted: 21 April 1999     

Dynamical analysis of balance in vestibular schwannoma patients

The analysis of the complexity of postural fluctuations is a recent method for assessing postural control. Complexity relates to the irregularity of the center of pressure time series and characterizes the ability of postural control to meet a changing environment. In our study, we used the sample entropy (SampEn) parameter to evaluate the complexity of postural sway velocity time series in patients with vestibular schwannoma (n = 19) compared to healthy controls (n = 20), using the sensory organization test. Patients performed postural assessments three days before surgical ablation of the tumor, then three times after surgery, at eight, thirty, and ninety days. The control group underwent posturographic tests only once. Our results demonstrated that SampEn values distinguished both groups before surgery only in postural tasks where vestibular afferences significantly contribute to maintaining balance. We also found an immediate decrease of complexity after the surgical resection of the tumor. Our results are in line with the theory of complexity loss of physiological systems stating that reducing the number of their structural components or altering their coupling leads to a decrease in complexity. Finally, our findings showed that progressive restoration of complexity over time was such that no difference was found between the two groups ninety days after surgery, due to the implementation of central adaptive mechanisms and the substitution by other sensory afferences. Thus, the SampEn parameter can highlight the postural effects of vestibular pathology, and complexity analysis appears to be a valuable tool for investigating the temporal structure of CoP time series.     

Image-guided stereotactic radiotherapy for patients with vestibular schwannoma

Strahlentherapie und Onkologie - Local tumor control and functional outcome after linac-based stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (FSRT) for vestibular...     

A vascular sarcoid mass mimicking a convexity meningioma

We report a 48-year-old woman with a left posterior temporal extra-axial mass that had the imaging characteristics of a meningioma on preoperative CT, MRI and angiography. However, a biopsy diagnosis of sarcoidosis was made. This case illustrates that dural-based sarcoid masses can be very vascular and radiographically indistinguishable from meningiomas. Characteristic imaging features of extra- and intra-axial sarcoid lesions are discussed. Received: 4 March 1999/Accepted: 11 June 1999     

Prevalence of hydrocephalus in 157 patients with vestibular schwannoma

The purpose of this study was to determine the prevalence of hydrocephalus in patients with vestibular schwannoma. A second objective was to investigate possible etiologies for hydrocephalus in this population by attempting to correlate the incidence and severity of hydrocephalus with tumor volume and extent of fourth ventricular compression. The MRI examinations of 157 adult patients with vestibular schwannoma were retrospectively reviewed. Tumor size was quantified, and the presence of accompanying hydrocephalus was assessed, categorized as communicating type or non-communicating type and then rated as mild, moderate or severe (grades 1–3). Next, the degree of fourth ventricular distortion caused by tumor mass effect was evaluated and categorized as mild, moderate or severe (grades 1–3). Spearmans rank correlation coefficient was used to test the relationships between tumor volume and (1) the extent of fourth ventricular effacement and (2) severity of hydrocephalus. Hydrocephalus was present in 28/157 (18%) cases and was categorized as mild in 11/28 (39%), moderate in 15/28 (54%) and severe in 2/28 (7%). Communicating-type hydrocephalus was present in 17/28 (61%) and non-communicating type in 11/28 (39%). There was a positive correlation between the grade of non-communicating hydrocephalus and tumor volume (r=0.38; P<0.001) and between the severity of fourth ventricular compression and extent of hydrocephalus in this group(r=0.43; P<0.001). In patients who were classified as having communicating hydrocephalus, the correlation between tumor volume and the severity of hydrocephalus was poor (r=0.19; P=0.02) as was the correlation between the extent of fourth ventricular distortion and the severity of hydrocephalus (r=0.21; P<0.01). There is a high prevalence of hydrocephalus in patients with vestibular schwannoma. In a minority of cases non-communicating type hydrocephalus is present and the severity of hydrocephalus can be attributed to the affect of tumor volume on fourth ventricular compression. More commonly, however, communicating-type hydrocephalus exists and the correlation between the severity of fourth ventricular compression and extent of hydrocephalus is poor. Therefore, other etiologies for hydrocephalus, such as tumor protein sloughing, are likely relevant.     

Chordoma mimicking the trigeminal schwannoma: a case report

Intracranial chordomas are rare tumor arising from the remnants of embryologic notochord. Bony destruction and tumor calcification are their characters. Now we represent an extra-axial tumor with an unusual dumbbell shape in the right Meckel's cave and the appearance mimics the trigeminal schwannomas. However, the histopathological findings reveal a chordoma. Bony destruction in the right petrous bone and clivus provides a hint to make appropriate diagnosis.     

Cystic schwannoma mimicking a brain stem tumor: MR features

A case of cystic schwannoma that presented as an intraaxial lesion on CT is reported. Magnetic resonance was able to detect the extraaxial origin of the tumor.     

A case report of pilocytic astrocytoma mimicking meningioma on imaging

Pilocytic astrocytoma (PA) is categorized as grade I gliomas with a good prognosis. Although PA mostly occurs in the cerebellum, it also can occur in the orbital and mostly presents as a cystic tumor with a mural nodule. PA often presents in the second decade of life, with 75% occurring under the age of 20 years. This case report describes a 10-year-old boy presented a left eye tumor for over 3 years. MRI examination showed unrestricted intraconal lesions in the optic nerve, visible from the optic canal to the anterior with well-defined borders. The excised tumor specimen depicted a nodular tumor tissue, measuring 35 × 28 × 20 mm, weighing 11 grams, solid with gray and white. The microscopic examination showed a classical biphasic pattern including combinations of loose glial tissue and compact pyloid tissue. Hispathology result revealed a pilocytic astrocytoma.     

Serial follow-up MR imaging after gamma knife radiosurgery for vestibular schwannoma

BACKGROUND AND PURPOSE: Gamma knife radiosurgery has become an important treatment option for vestibular schwannoma. The effect of treatment can be assessed only by neuroimaging. We analyzed the evolution of follow-up MR imaging findings after gamma knife radiosurgery to provide information for the clinical management of these tumors. METHODS: Changes in tumor volume and enhancement were assessed visually on 341 follow-up MR studies obtained in 78 of 86 consecutive patients with unilateral vestibular schwannoma who underwent gamma knife radiosurgery. RESULTS: Follow-up MR studies were obtained between 10 and 63 months (mean, 34 months) after treatment. Tumor control rate was 81%. Changes in tumor volume were classified as temporary enlargement (41%), no change or sustained regression (34%), alternating enlargement and regression (13%), or continuous enlargement (12%). Temporary enlargement occurred within 2 years after radiosurgery. Changes in tumor enhancement were classified as transient loss of enhancement (84%), continuous increase in enhancement (5%), or no change in enhancement (11%). There was no significant correlation between changes in tumor volume and tumor enhancement. Areas of T2 hyperintensity in adjacent brain tissue appeared in 31% of patients. CONCLUSION: Dynamic changes in vestibular schwannoma are seen on serial follow-up MR studies obtained after gamma knife radiosurgery. An increase in tumor size up to 2 years after radiosurgery is likely to be followed by regression. Changes in contrast enhancement are not predictive of clinical outcome. Neuroimaging follow-up is recommended.     

Fractionated vs. single-fraction stereotactic radiotherapy in patients with vestibular schwannoma

Background

Stereotactic radiotherapy (RT) has been established as a valid treatment alternative in patients with vestibular schwannoma (VS). There is ongoing controversy regarding the optimal fractionation. Hearing preservation may be the primary goal for patients with VS, followed by maintenance of quality of life (QoL).

Methods

From 2002 to 2015, 184 patients with VS were treated with radiosurgery (RS) or fractionated stereotactic radiotherapy (FSRT). A survey on current symptoms and QoL was conducted between February and June 2016.

Results

Median follow-up after RT was 7.5 years (range 0–14.4 years). Mean overall survival (OS) after RT was 31.1 years, with 94 and 87% survival at 5 and 10 years, respectively. Mean progression-free survival (PFS) was 13.3 years, with 5? and 10-year PFS of 92%. Hearing could be preserved in RS patients for a median of 36.3 months (range 2.3–13.7 years). Hearing worsened in 17 (30%) cases. Median hearing preservation for FSRT was 48.7 months (range 0.0–13.8 years); 29 (23%) showed hearing deterioration. The difference in hearing preservation was not significant between RS and FSRT (p = 0.3). A total of 123/162 patients participated in the patient survey (return rate 76%). The results correlate well with the information documented in the patient files for tinnitus and facial and trigeminal nerve toxicity. Significant differences appeared regarding hearing impairment, gait uncertainty, and imbalance.

Conclusion

These data confirm that RS and FSRT are comparable in terms of local control for VS. RS should be reserved for smaller lesions, while FSRT can be offered independently of tumor size. Patient self-reported outcome during follow-up is of high value. The established questionnaire could be validated in the independent cohort.