Eighty eight patients with increased intracranial symptoms were diagnosed during the study time period. Of them, 6 patients (3 males, 3 females) with an average age of 52 years (mean standard deviation 52 ± 14, range 27–67) were diagnosed with OT that causes venous outflow obstruction (study group). The control group included 6 patients (2 males, 4 females) average age of 52 years (mean standard deviation 52 ± 18, range 20–72).

Past medical history of the study group included: one had carcinoma of the breast, one had prostate cancer, and one was post-resection and radiotherapy for frontal anaplastic meningioma. The past medical history of the patients with meningiomas in the study group included one patient who received radiation because of tinea capitis during childhood, and one patient who sustained a cerebrovascular accident 16 years earlier. Past medical history of the control group included: asthma, hypertension, hyperlipidemia.

The mean (± SD) body mass index (BMI) of the study group was 26.45±5.57 while for the control group it was 26.96±0.70 (t-test, p = 0.892).

The mean duration of symptoms, for the study group, before diagnosis was 22±21.36 days (range 0–60) while for the control group 156.67±159.36 days (0-365) (t-test, p = 0.047). In the study group, only one patient had no symptoms and optic disc edema was found incidentally during a routine eye examination while in the control group all patients had a clinical presenting symptom.

The neurological and ophthalmological symptoms and signs at presentation for both groups are summarized in Tables 1 and 2.

In the study group, one patient had Freisen grade + 1, 3 Freisen grade + 2 and 2 patients had Freisen grade + 4 while in the control group 1 patient had Freisen grade + 1 (Fig. 1A-D).

Optic disc and visual fields. A Patient 3- OU: Freisen + 2; VF: Enlarged BS and residual old small homonymous from old stroke as 15 years prior. B Patient 4- OU: Freisen + 1; VF: Not significant VF disturbance (very mild enlarged BS). C Patient 5- OU: Freisen + 4; VF: Enlarged BS and nasal defect. D Patient 6- OU: Freisen + 2; VF: Enlarged BS and Constricted VF. Abbreviations: OU- both eyes; VF- Visual Fields; BS-Blind spot

Visual fields of the study group, at presentation, included: an enlarged blind spot for all patients, nasal or arcuate depression for three patients, generalized field constriction for one patient (Fig. 1A-D). None had a homonymous VF defect at presentation, with the exception of the patient with a history of cerebrovascular accident who had a small residual VF defect (Fig. 1A). In the control group, 4 patients had homonymous VF defect at presentation (chi_squ, p = 0.041) (Fig. 1B).

All patients underwent MRI and MRV or CTV. In the study group, an occlusion of the venous drainage system was found in all patients while in the control group it was not found. Tumor-compressed venous drainage was observed in all study patients. Secondary thrombosis was detected in 3 patients, and meningioma appeared to infiltrate the venous system of one patient. The tumor in the study group was a meningioma in 4 patients with several locations (bilateral infra- and supratentorial patient # 1 right parasagittal patient #2, left parasagittal patient #3, left occipital anaplastic meningioma patient#6). The other 2 patients were diagnosed with occipital lobe metastasis whose primary sites were prostate (patient #5) and thyroid (patient #4). In the control group, 4 patients had meningioma in the occipital lobe, 1 patient had Glioblastoma multiforme (GBM)- CNS WHO grade 4 in the parieto-occipital lobe and one patient had Papillary Glioneuronal Tumor (PGNT) in the occipital lobe. The average volume of the tumor in the study group was 41,221 mm [3] while in the control group 31,264 mm [3] (t-test, p = 0.624). No empty Sella turcica were demonstrated in the study group while one patient had empty Sella turcica in the control group (chi_squ, p = 0.296). None of the patients, in both groups had flattening of the posterior optic globe.

Five of the study patients underwent lumbar puncture (the sixth refused), and the mean opening pressure was 297.5 mmH2O (mean 297.5 ± 46.5, range 250–360). The cerebrospinal fluid composition was within normal limits except mild elevation of protein level 50 mg/dl(upper limit < 45 mg/dl.) in one meningioma patient.

During the follow-up period of the study group, which lasted an average of 5.38 years (mean 5.38±4.73, range 1.3–14), all 6 patients (100%) were treated with acetazolamide and 5 patients (83.33%) were treated with dexamethasone. Three patients were also treated with enoxaparin for thrombosis. The surgical management for the acute elevated ICP, was discussion with the neurosurgery team. Five (83.33%) patients underwent insertion of a ventriculoperitoneal shunt because of visual function deterioration despite maximal tolerated medical treatment. Two patients (33.33%) were treated with continuous drainage of, and one patient (16.67%) underwent optic nerve fenestration due to visual function deterioration. Following those acute treatments, all 6 study group patients underwent radiosurgery for tumor treatment, while 3 also underwent partial resection followed by radiotherapy.

The follow- up period of the control group was 5.30 years (mean 5.30±3.37, range 0.8–10). During this period of time, all patients underwent resection of the tumor and 2 patients underwent radiosurgery.

At the end of follow-up, 2 patients, from the study group, died: one from anaplastic meningioma and one from GBM, and the remaining 4 patients from the study group, were stable. In the control group, all patients were alive at the end of follow- up but one patient developed epilepsy and deterioration in cognitive status.

None of the study group patients, with the exception of one who developed optic disc atrophy and visual deterioration, had visual complaints at the end of follow-up. In the control group, 3 patients had deterioration in the visual field at the end of follow up. There were no significant differences at the end of follow up in the clinical signs between groups (Table 3).

A comparison between clinical signs at presentation vs. at the end of follow-up did not show significant differences in clinical characteristics at the study group. Atrophy of the disc at the end of follow-up was found in 1 of the 6 patients and no patient had disc edema.

We report 2 of the cases from the study group in detail to demonstrate their clinical course.

This was a 47-year-old male who presented to the ophthalmology emergency room complaining of headache during the preceding 2 months and the onset of blurred vision during last few days. His past medical history was significant for having donated a kidney to his son 2 years prior. His visual functions at presentation were abnormal. The dilated fundus examination revealed optic disc edema (Fig. 2A), the MRI showed large bilateral infra and supra-tentorial meningiomas and the CTV demonstrated penetration of the meningioma to the confluent (Fig. 2B) and sagittal sinuses (Fig. 2C) but he refused to undergo LP. He was treated with acetazolamide and dexamethasone. Due to his damaged VF, VP shunting was recommended but he declined and left the hospital. Subsequently, he returned while sustaining deterioration of his vision and underwent an urgent VP shunt surgery and bilateral optic nerve sheath fenestration followed by radiotherapy for the meningioma. His vision continued to deteriorate to 20/400 in his right eye and hand movement in his left eye, despite all the above procedures to avoid optic atrophy and blindness.

Case number 1. Fundus examination: Bilateral optic discs edema (A). CTV examination: meningioma penetration to the confluent sinus (B). CTV examination: meningioma penetration to the sagittal sinus (C)

This was a 62-year-old female with recent diagnosis of breast carcinoma. She was referred to the ophthalmology emergency room due to bilateral optic disc edema found incidentally during a routine examination. The MRI showed a space-occupying lesion in the occipital lobe, and the MRV showed compression of the sigmoid and transverse venous sinuses (Fig. 3A-B). She was treated with prednisone and acetazolamide which led to improvement in the disc edema. The neurosurgical consultant recommended a follow-up MRI under the presumption that the tumor was a meningioma, while another neurosurgeon recommended resection. Finally, she decided to be treated medically. However, in the meantime, a thyroid nodule was diagnosed and so she underwent partial thyroidectomy that revealed follicular thyroid carcinoma. After 8 months since presentation to the ophthalmology service the size of the occipital lesion increased on follow-up MRI and resection was again recommended. She then underwent craniotomy and biopsy of the occipital SOL. The histopathological result was follicular thyroid carcinoma metastasis. Consequently, she underwent radiosurgery for the brain lesion and thyroidectomy 2 weeks later and then started radioactive iodine therapy. Four months after radiosurgery the optic disc edema worsened and the blind spot in the VF has increased. She underwent the insertion of a VP shunt which resulted in stabilization of the tumor size and resolution of the disc edema.

Case number 2. MRI examination: space-occupying lesion in the occipital lobe (A). MRV examination: compression of the sigmoid and transverse venous sinus (B)