Good Visual Outcomes After Pituitary Tumor Surgery Are Associated With Increased Visual Cortex Functional Connectivity.

BACKGROUND: Patients presenting with visual impairment secondary to pituitary macroadenomas often experience variable recovery after surgery. Several factors may impact visual outcomes including the extent of neuroaxonal damage in the afferent visual pathway and cortical plasticity. Optical coherence tomography (OCT) measures of retinal structure and resting-state functional MRI (rsfMRI) can be used to evaluate the impact of neuroaxonal injury and cortical adaptive processes, respectively. The purpose of this study was to determine whether rsfMRI patterns of functional connectivity (FC) distinguish patients with good vs poor visual outcomes after surgical decompression of pituitary adenomas. METHODS: In this retrospective cohort study, we compared FC patterns between patients who manifested good (GO) vs poor (PO) visual outcomes after pituitary tumor surgery. Patients (n = 21) underwent postoperative rsfMRI a minimum of 1 year after tumor surgery. Seed-based connectivity of the visual cortex (primary [V1], prestriate [V2], and extrastriate [V5]) was compared between GO and PO patients and between patients and healthy controls (HCs) (n = 19). Demographics, visual function, and OCT data were compared preoperatively and postoperatively between patient groups. The threshold for GO was visual field mean deviation equal or less than -5.00 dB and/or visual acuity equal to or better than 20/40. RESULTS: Increased postoperative FC of the visual system was noted for GO relative to PO patients. Specifically, good visual outcomes were associated with increased connectivity of right V5 to the bilateral frontal cortices. Compared with HCs, GO patients showed increased connectivity of V1 and left V2 to sensorimotor cortex, increased connectivity of right and left V2 to medial prefrontal cortex, and increased connectivity of right V5 the right temporal and frontal cortices. CONCLUSIONS: Increased visual cortex connectivity is associated with good visual outcomes in patients with pituitary tumor, at late phase of recovery. Our findings suggest that rsfMRI does distinguish GO and PO patients after pituitary tumor surgery. This imaging modality may have a future role in characterizing the impact of cortical adaptation on visual recovery.

Endoscopic transnasal resection of optic pathway pilocytic astrocytoma.

PURPOSE: Optic pathway gliomas (OPGs) are low-grade neoplasms that primarily affect children. The management of OPGs remains controversial. Reports on the use of the endoscopic endonasal approach (EEA) in OPGs are extremely limited, and no such reports exist on its utility for pediatric OPGs. Here, we report our results and experience with OPGs treated with the EEA. METHODS: We retrospectively reviewed the medical records of OPG patients who were treated surgically via the EEA at our institutions from 2015 to 2017. Data on the demographics, clinical presentation, surgical complications, clinical outcomes, radiological imaging, and visual outcomes were recorded for each patient. RESULTS: Four cases were identified, with visual disturbances being the predominant complaint. The mean patient age was 15.5 years. Three cases showed normal preoperative hormonal profiles, but one patient had hypothyroidism. All tumors identified in this study were World Health Organization grade I pilocytic astrocytomas. Surgical complications included hypopituitarism in two patients, meningitis in two patients, cerebrospinal fluid leak in one patient, and transient diabetes insipidus in one patient. No patient experienced worsening neurological or visual symptoms postoperatively. CONCLUSIONS: Although our data are preliminary, the EEA provides a direct corridor to OPG with acceptable results in terms of tumor resection and visual outcomes. Hypothalamic-pituitary axis dysfunction remains a limitation of any treatment modality for OPGs and should be considered whenever possible. Definitive conclusions are pending as the learning curve of this approach is steep. Further work is needed to understand patient selection for such an approach.

Meyer's loop tractography for image-guided surgery depends on imaging protocol and hardware.

Introduction: Surgical resection is an effective treatment for temporal lobe epilepsy but can result in visual field defects. This could be minimized if surgeons knew the exact location of the anterior part of the optic radiation (OR), the Meyer's loop. To this end, there is increasing prevalence of image-guided surgery using diffusion MRI tractography. Despite considerable effort in developing analysis methods, a wide discrepancy in Meyer's loop reconstructions is observed in the literature. Moreover, the impact of differences in image acquisition on Meyer's loop tractography remains unclear. Here, while employing the same state-of-the-art analysis protocol, we explored the extent to which variance in data acquisition leads to variance in OR reconstruction. Methods: Diffusion MRI data were acquired for the same thirteen healthy subjects using standard and state-of-the-art protocols on three scanners with different maximum gradient amplitudes (MGA): Siemens Connectom (MGA = 300 mT/m); Siemens Prisma (MGA = 80 mT/m) and GE Excite-HD (MGA = 40 mT/m). Meyer's loop was reconstructed on all subjects and its distance to the temporal pole (ML-TP) was compared across protocols. Results: A significant effect of data acquisition on the ML-TP distance was observed between protocols (p < .01 to 0.0001). The biggest inter-acquisition discrepancy for the same subject across different protocols was 16.5 mm (mean: 9.4 mm, range: 3.7-16.5 mm). Conclusion: We showed that variance in data acquisition leads to substantive variance in OR tractography. This has direct implications for neurosurgical planning, where part of the OR is at risk due to an under-estimation of its location using conventional acquisition protocols.

Optical coherence tomography impacts the evaluation of visual pathway tumors.

The objective of this systematic literature review is to assess the role of retinal optical coherence tomography (OCT) in the evaluation of patients with tumors of the visual pathway. We performed a PubMed database search according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The search was restricted to articles published in English between 2000 and 2016, with at least 10 human adult participants enrolled. Twenty-seven articles met the eligibility criteria. All studies investigated tumors of the anterior visual pathway. Both time-domain and spectral-domain OCT technologies were used and the role of OCT as diagnostic and/or prognostic tool was studied. Retinal OCT provides structural information about ganglion cell axon integrity and is complementary to visual function examination. OCT is a prognostic factor for post-operative visual outcome.

Monocular denervation of visual nuclei modulates APP processing and sAPPα production: A possible role on neural plasticity.

Amyloid precursor protein (APP) is essential to physiological processes such as synapse formation and neural plasticity. Sequential proteolysis of APP by beta- and gamma-secretases generates amyloid-beta peptide (Aß), the main component of senile plaques in Alzheimer Disease. Alternative APP cleavage by alpha-secretase occurs within Aß domain, releasing soluble α-APP (sAPPα), a neurotrophic fragment. Among other functions, sAPPα is important to synaptogenesis, neural survival and axonal growth. APP and sAPPα levels are increased in models of neuroplasticity, which suggests an important role for APP and its metabolites, especially sAPPα, in the rearranging brain. In this work we analyzed the effects of monocular enucleation (ME), a classical model of lesion-induced plasticity, upon APP content, processing and also in secretases levels. Besides, we addressed whether α-secretase activity is crucial for retinotectal remodeling after ME. Our results showed that ME induced a transient reduction in total APP content. We also detected an increase in α-secretase expression and in sAPP production concomitant with a reduction in Aß and ß-secretase contents. These data suggest that ME facilitates APP processing by the non-amyloidogenic pathway, increasing sAPPα levels. Indeed, the pharmacological inhibition of α-secretase activity reduced the axonal sprouting of ipsilateral retinocollicular projections from the intact eye after ME, suggesting that sAPPα is necessary for synaptic structural rearrangement. Understanding how APP processing is regulated under lesion conditions may provide new insights into APP physiological role on neural plasticity.

Functional Magnetic Resonance Imaging (fMRI), Pre-intraoperative Tractography in Neurosurgery: The Experience of Sant' Andrea Rome University Hospital.

BACKGROUND: The goal of neurosurgery for cerebral intraparenchymal neoplasms of the eloquent areas is maximal resection with the preservation of normal functions, and minimizing operative risk and postoperative morbidity. Currently, modern technological advances in neuroradiological tools, neuronavigation, and intraoperative magnetic resonance imaging (MRI) have produced great improvements in postoperative morbidity after the surgery of cerebral eloquent areas. The integration of preoperative functional MRI (fMRI), intraoperative MRI (volumetric and diffusion tensor imaging [DTI]), and neuronavigation, defined as "functional neuronavigation" has improved the intraoperative detection of the eloquent areas. METHODS: We reviewed 142 patients operated between 2004 and 2010 for intraparenchymal neoplasms involving or close to one or more major white matter tracts (corticospinal tract [CST], arcuate fasciculus [AF], optic radiation). All the patients underwent neurosurgery in a BrainSUITE equipped with a 1.5 T MR scanner and were preoperatively studied with fMRI and DTI for tractography for surgical planning. The patients underwent MRI and DTI during surgery after dural opening, after the gross total resection close to the white matter tracts, and at the end of the procedure. We evaluated the impact of fMRI on surgical planning and on the selection of the entry point on the cortical surface. We also evaluated the impact of preoperative and intraoperative DTI, in order to modify the surgical approach, to define the borders of resection, and to correlate this modality with subcortical neurophysiological monitoring. We evaluated the impact of the preoperative fMRI by intraoperative neurophysiological monitoring, performing "neuronavigational" brain mapping, following its data to localize the previously elicited areas after brain shift correction by intraoperative MRI. RESULTS: The mean age of the 142 patients (89 M/53 F) was 59.1 years and the lesion involved the CST in 66 patients (57 %), the language pathways in 24 (21 %), and the optic radiations in 25 (22 %). The integration of tractographic data into the volumetric dataset for neuronavigation was technically possible in all cases. In all patients intraoperative DTI demonstrated a shift of the bundle position caused by the surgical procedure; its dislocation was both outward and inward in the range of +6 mm and -2 mm. CONCLUSION: We found a high concordance between fMRI/DTI and intraoperative brain mapping; their combination improves the sensitivity of each technique, reducing pitfalls and so defining "functional neuronavigation", increasing the definition of eloquent areas and also reducing the time of surgery.

Elaboration of the Visual Pathways from the Study of War-Related Cranial Injuries: The Period from the Russo-Japanese War to World War I.

As a result of the wars in the early 20th century, elaboration of the visual pathways was greatly facilitated by the meticulous study of visual defects in soldiers who had suffered focal injuries to the visual cortex. Using relatively crude techniques, often under difficult wartime circumstances, investigators successfully mapped key features of the visual pathways. Studies during the Russo- Japanese War (1904-1905) by Tatsuji Inouye (1881-1976) and during World War I by Gordon Holmes (1876-1965), William Lister (1868-1944), and others produced increasingly refined retinotopic maps of the primary visual cortex, which were later supported and refined by studies during and after World War II. Studies by George Riddoch (1888-1947) during World War I also demonstrated that some patients could still perceive motion despite blindness caused by damage to their visual cortex and helped to establish the concept of functional partitioning of visual processes in the occipital cortex.

Distinct displacements of the optic radiation based on tumor location revealed using preoperative diffusion tensor imaging.

OBJECT Visual field defects (VFDs) due to optic radiation (OR) injury are a common complication of temporal lobe surgery. The authors analyzed whether preoperative visualization of the optic tract would reduce this complication by influencing the surgeon's decisions about surgical approaches. The authors also determined whether white matter shifts caused by temporal lobe tumors would follow predetermined patterns based on the tumor's topography. METHODS One hundred thirteen patients with intraaxial tumors of the temporal lobe underwent preoperative diffusion tensor imaging (DTI) fiber tracking. In 54 of those patients, both pre- and postoperative VFDs were documented using computerized perimetry. Brainlab's iPlan 2.5 navigation software was used for tumor reconstruction and fiber visualization after the fusion of DTI studies with their respective magnetization-prepared rapid gradient-echo (MP-RAGE) images. The tracking algorithm was as follows: minimum fiber length 100 mm, fractional anisotropy threshold 0.1. The lateral geniculate body and the calcarine cortex were employed as tract seeding points. Shifts of the OR caused by tumor were visualized in comparison with the fiber tracking of the patient's healthy hemisphere. RESULTS Temporal tumors produced a dislocation of the OR but no apparent fiber destruction. The shift of white matter tracts followed fixed patterns dependent on tumor location: Temporolateral tumors resulted in a medial fiber shift, and thus a lateral transcortical approach is recommended. Temporopolar tumors led to a posterior shift, always including Meyer's loop; therefore, a pterional transcortical approach is recommended. Temporomesial tumors produced a lateral and superior shift; thus, a transsylvian-transcisternal approach will result in maximum sparing of the fibers. Temporocentric tumors also induced a lateral fiber shift. For those tumors, a transsylvian-transopercular approach is recommended. Tumors of the fusiform gyrus generated a superior (and lateral) shift; consequently, a subtemporal approach is recommended to avoid white matter injury. In applying the approaches recommended above, new or worsened VFDs occurred in 4% of the patient cohort. Total neurological and surgical morbidity were less than 10%. In 90% of patients, gross-total resection was accomplished. CONCLUSIONS Preoperative visualization of the OR may help in avoiding postoperative VFDs.

Diffusion tensor imaging--arcuate fasciculus and the importance for the neurosurgeon.

OBJECTIVE: Tumors in eloquent areas of the brain like Broca or Wernicke might have disastrous consequences for patients. We intended to visualize the arcuate fasciculus (AF) and to demonstrate his relation with the corticospinal tract and the visual pathway using diffusion tensor imaging (DTI). METHODS: We depicted between 2012 and 2014 the AF in 71 patients. Men and women of all ages were included. Eleven patients had postoperative controls also. We used a 3DT1-sequence for the navigation. Furthermore T2- and DTI-sequences were performed. The FOV was 200 × 200 mm(2), slice thickness 2mm, and an acquisition matrix of 96 × 96 yielding nearly isotropic voxels of 2 × 2 × 2 mm. 3-Tesla-MRI was carried out strictly axial using 32 gradient directions and one b0-image. We used Echo-Planar-Imaging (EPI) and ASSET parallel imaging with an acceleration factor of 2. b-Value was 800 s/mm(2). Additional scanning time was less than 9 min. RESULTS: AF was portrayed in 63 patients bilaterally. In one glioblastoma patient it was impossible to visualize the left AF and in seven other patients we could not portray the right one. The lesions affected AF by disrupting or displacing the fibers. CONCLUSIONS: DTI might be a useful tool to portray AF. It is time-saving and can be used to preserve morbidity in patients with lesions in eloquent brain areas. It might give deeper insights of the white matter and the reorganization of AF-fibers postoperatively.

Diffusion tensor imaging tractography of Meyer's loop in planning resective surgery for drug-resistant temporal lobe epilepsy.

PURPOSE: Whether Meyer's loop (ML) tracking using diffusion tensor imaging tractography (DTIT) can be utilized to avoid post-operative visual field deficits (VFD) after anterior temporal lobectomy (ATL) for drug-resistant temporal lobe epilepsy (TLE) using a large cohort of controls and patients. Also, we wanted to create a normative atlas of ML in normal population. METHODS: DTIT was used to study ML in 75 healthy subjects and 25 patients with and without VFD following ATL. 1.5T MRI echo-planar DTI sequences with DTI data were processed in Nordic ICE using a probabilistic method; a multiple region of interest technique was used for reconstruction of optic radiation trajectory. Visual fields were assessed in patients pre- and post-operatively. RESULTS: Results of ANOVA showed that the left ML-TP distance was less than right across all groups (p = 0.01). The average distance of ML from left temporal pole was 37.44 ± 4.7 mm (range: 32.2-46.6 mm) and from right temporal pole 39.08 ± 4.9 mm (range: 34.3-49.7 mm). Average distance of left and right temporal pole to tip of temporal horn was 28.32 ± 2.03 mm (range: 26.4-32.8 mm) and was 28.92 ± 2.09 mm, respectively (range: 25.9-33.3 mm). If the anterior limit of the Meyer's loop was ≤38 mm on the right and ≤35 mm on the left from the temporal pole, they are at a greater risk of developing VFDs. CONCLUSIONS: DTIT is a novel technique to delineate ML and plays an important role in planning surgical resection in TLE to predict post-operative visual performance and disability.

DTI of the visual pathway - white matter tracts and cerebral lesions.

DTI is a technique that identifies white matter tracts (WMT) non-invasively in healthy and non-healthy patients using diffusion measurements. Similar to visual pathways (VP), WMT are not visible with classical MRI or intra-operatively with microscope. DIT will help neurosurgeons to prevent destruction of the VP while removing lesions adjacent to this WMT. We have performed DTI on fifty patients before and after surgery between March 2012 to January 2014. To navigate we used a 3DT1-weighted sequence. Additionally, we performed a T2-weighted and DTI-sequences. The parameters used were, FOV: 200 x 200 mm, slice thickness: 2 mm, and acquisition matrix: 96 x 96 yielding nearly isotropic voxels of 2 x 2 x 2 mm. Axial MRI was carried out using a 32 gradient direction and one b0-image. We used Echo-Planar-Imaging (EPI) and ASSET parallel imaging with an acceleration factor of 2 and b-value of 800 s/mm². The scanning time was less than 9 min. The DTI-data obtained were processed using a FDA approved surgical navigation system program which uses a straightforward fiber-tracking approach known as fiber assignment by continuous tracking (FACT). This is based on the propagation of lines between regions of interest (ROI) which is defined by a physician. A maximum angle of 50, FA start value of 0.10 and ADC stop value of 0.20 mm²/s were the parameters used for tractography. There are some limitations to this technique. The limited acquisition time frame enforces trade-offs in the image quality. Another important point not to be neglected is the brain shift during surgery. As for the latter intra-operative MRI might be helpful. Furthermore the risk of false positive or false negative tracts needs to be taken into account which might compromise the final results.

Preventing visual field deficits from neurosurgery.

OBJECTIVE: We assessed whether display of optic radiation tractography during anterior temporal lobe resection (ATLR) for refractory temporal lobe epilepsy (TLE) can reduce the severity of postoperative visual field deficits (VFD) and increase the proportion of patients who can drive and whether correction for brain shift using intraoperative MRI (iMRI) is beneficial. METHODS: A cohort of 21 patients underwent ATLR in an iMRI suite. Preoperative tractography of the optic radiation was displayed on the navigation and operating microscope displays either without (9 patients) or with (12 patients) correction for brain shift. VFD were quantified using Goldmann perimetry and eligibility to drive was assessed by binocular Esterman perimetry 3 months after surgery. Secondary outcomes included seizure freedom and extent of hippocampal resection. The comparator was a cohort of 44 patients who underwent ATLR without iMRI. RESULTS: The VFD in the contralateral superior quadrant were significantly less (p = 0.043) with iMRI guidance (0%-49.2%, median 14.5%) than without (0%-90.9%, median 24.0%). No patient in the iMRI cohort developed a VFD that precluded driving whereas 13% of the non-iMRI cohort failed to meet UK driving criteria. Outcome did not differ between iMRI guidance with and without brain shift correction. Seizure outcome and degree of hippocampal resection were unchanged. CONCLUSIONS: Display of the optic radiation with image guidance reduces the severity of VFD and did not affect seizure outcome or hippocampal resection. Correction for brain shift is possible but did not further improve outcome. Future work to incorporate tractography into conventional neuronavigation systems will make the work more widely applicable.

Fractionated stereotactic radiosurgery for patients with skull base metastases from systemic cancer involving the anterior visual pathway.

BACKGROUND: To analyze the tumor control, survival outcomes, and toxicity after stereotactic radiosurgery (SRS) for skull base metastases from systemic cancer involving the anterior visual pathway. PATIENTS AND METHODS: We have analyzed 34 patients (23 females and 11 males, median age 59 years) who underwent multi-fraction SRS for a skull base metastasis compressing or in close proximity of optic nerves and chiasm. All metastases were treated with frameless LINAC-based multi-fraction SRS in 5 daily fractions of 5 Gy each. Local control, distant failure, and overall survival were estimated using the Kaplan-Meier method calculated from the time of SRS. Prognostic variables were assessed using log-rank and Cox regression analyses. RESULTS: At a median follow-up of 13 months (range, 2-36.5 months), twenty-five patients had died and 9 were alive. The 1-year and 2-year local control rates were 89% and 72%, and respective actuarial survival rates were 63% and 30%. Four patients recurred with a median time to progression of 12 months (range, 6-27 months), and 17 patients had new brain metastases at distant brain sites. The 1-year and 2-year distant failure rates were 50% and 77%, respectively. On multivariate analysis, a Karnofsky performance status (KPS) >70 and the absence of extracranial metastases were prognostic factors associated with lower distant failure rates and longer survival. After multi-fraction SRS, 15 (51%) out of 29 patients had a clinical improvement of their preexisting cranial deficits. No patients developed radiation-induced optic neuropathy during the follow-up. CONCLUSIONS: Multi-fraction SRS (5 x 5 Gy) is a safe treatment option associated with good local control and improved cranial nerve symptoms for patients with a skull base metastasis involving the anterior visual pathway.

Nonthermal ablation with microbubble-enhanced focused ultrasound close to the optic tract without affecting nerve function.

OBJECT: Tumors at the skull base are challenging for both resection and radiosurgery given the presence of critical adjacent structures, such as cranial nerves, blood vessels, and brainstem. Magnetic resonance imaging-guided thermal ablation via laser or other methods has been evaluated as a minimally invasive alternative to these techniques in the brain. Focused ultrasound (FUS) offers a noninvasive method of thermal ablation; however, skull heating limits currently available technology to ablation at regions distant from the skull bone. Here, the authors evaluated a method that circumvents this problem by combining the FUS exposures with injected microbubble-based ultrasound contrast agent. These microbubbles concentrate the ultrasound-induced effects on the vasculature, enabling an ablation method that does not cause significant heating of the brain or skull. METHODS: In 29 rats, a 525-kHz FUS transducer was used to ablate tissue structures at the skull base that were centered on or adjacent to the optic tract or chiasm. Low-intensity, low-duty-cycle ultrasound exposures (sonications) were applied for 5 minutes after intravenous injection of an ultrasound contrast agent (Definity, Lantheus Medical Imaging Inc.). Using histological analysis and visual evoked potential (VEP) measurements, the authors determined whether structural or functional damage was induced in the optic tract or chiasm. RESULTS: Overall, while the sonications produced a well-defined lesion in the gray matter targets, the adjacent tract and chiasm had comparatively little or no damage. No significant changes (p > 0.05) were found in the magnitude or latency of the VEP recordings, either immediately after sonication or at later times up to 4 weeks after sonication, and no delayed effects were evident in the histological features of the optic nerve and retina. CONCLUSIONS: This technique, which selectively targets the intravascular microbubbles, appears to be a promising method of noninvasively producing sharply demarcated lesions in deep brain structures while preserving function in adjacent nerves. Because of low vascularity--and thus a low microbubble concentration--some large white matter tracts appear to have some natural resistance to this type of ablation compared with gray matter. While future work is needed to develop methods of monitoring the procedure and establishing its safety at deep brain targets, the technique does appear to be a potential solution that allows FUS ablation of deep brain targets while sparing adjacent nerve structures.

Presence of fusion in albinism after strabismus surgery augmented with botulinum toxin (type a) injection.

It is commonly accepted that albino patients with strabismus rarely achieve binocularity and depth perception after strabismus surgery. The presence of retino-geniculo-cortical misrouting, a hallmark of the visual system in albinism, does not necessarily cause total loss of binocular vision, however, not even in albino patients with strabismus. Recently some degrees of stereopsis were reported in albinism patients with minimal clinical nystagmus, if any, in the absence of strabismus. It is possible that patients with albinism and strabismus have binocular visual potential which appears after strabismus correction and provides appropriate postoperative alignment in the long term. Here we present two cases of clinically diagnosed oculocutaneous albinism, an 18-year-old girl and a 16-year-old boy, both with exotropia ≥40 prism diopter, who gained acceptable alignment and fusion after surgical correction of their strabismus as demonstrated on Bagolini testing. In cases of albinism accompanied by visual pathway abnormalities and strabismus, binocular visual potential is not impossible, and some levels can be expected. Thus, these patients, like other cases of strabismus, may benefit from treatment of strabismus at an earlier age to achieve appropriate alignment, cosmetic satisfaction, and a possibly increased chance of fusion.

Imaging of the optic chiasm and retrochiasmal visual pathways.

The exploration of the chiasmal and retrochiasmal visual pathways is based on magnetic resonance imaging. A bitemporal hemianopsis suggests a lesion of the optic chiasm while homonymous lateral hemianopsis should lead to a search for a lesion of the retrochiasmal visual pathways. The causes of chiasmal impairment are mainly tumoral. The exploration protocol is based on MRI with T1-weighted sagittal sections, then T2- and T1-weighted coronal sections with and without injection. In case of a retrochiasmal syndrome, the MRI exploration protocol is a function of the type of occurrence of the deficiency and the context.

Late adult onset optic pathway astrocytoma.

A 70-year-old man presented with left-sided eye pain, impaired vision and restricted left ocular motility, later developing progressive visual decline with development of ataxia and incontinence. Fundoscopic examination revealed significant optic nerve head edema and hemorrhage on the left eye. Neuroimaging revealed an optic pathway mass, extending from the right optic nerve to the chiasm, which enlarged on serial imaging. After surgical excision of the mass, pathology showed a grade III astrocytoma. The patient died 16 months after presentation, which is longer than previously reported for late adult onset optic pathway astrocytoma. We believe that neuroimaging and pathological studies should be performed early in such patients to allow early diagnosis and intervention.

[Modern surgery of meningiomas affecting anterior visual pathways]. / Moderne Meningeomchirurgie im Bereich der vorderen Sehbahn.

Meningiomas are the most common form of primary intracranial tumors. If the anterior visual pathways are affected clinical visual compromise, visual field defects, oculomotor nerve disturbances or propotosis are predominant. Meningiomas of the anterior visual pathway remain therapeutically challenging due to the direct anatomical relationship to the circulus arteriosus cerebri, the cavernous sinus and cranial nerves. The therapy of choice is microsurgical resection. In many cases a curative approach can be achieved with modern surgical techniques and simultaneously maintaining patient quality of life. Problematic are cases in which resection would be associated with the risk of clinical impairment and in these cases radiotherapy is an important therapeutic option. In cases involving complex invasiveness an interdisciplinary treatment to control local clinical symptoms is favored.

[Meningiomas. Clinical case examples]. / Meningeome. Klinische Beispiele.

Using four case reports as examples the best treatment is discussed by considering the specific history and magnetic resonance imaging (MRI) findings. In many cases different therapeutic alternatives are possible for treatment of meningiomas.

Management of the optic canal invasion and visual outcome in spheno-orbital meningiomas.

OBJECTIVE: Spheno-orbital meningiomas often present with visual deficit due to invasion of the optic canal by the tumor. This study discusses the reasons of visual impairment, the choice of the surgical approach according to the type of optic canal involvement, and the factors correlated to the visual outcome in patients harboring a spheno-orbital meningioma. MATERIALS AND METHODS: A surgical series of 60 spheno-orbital meningiomas is reviewed. The preoperative visual symptoms, the involvement of the optic canal in both neuroradiological studies and surgical descriptions, the different surgical approaches are reviewed. These data are correlated with the postoperative visual outcome. RESULTS: The 60 spheno-orbital meningiomas were classified in 4 types according to the intraorbital tumor localization: type I, supero-lateral (18 cases); type II, inferomedial (8 cases); type III, orbital apex (22 cases); type IV, diffuse (12 cases). Thirty-six of the 60 patients (60%) had variable decrease of the visual acuity on the tumor side. Forty-three patients (71.6%) had tumor extension into the optic canal on imaging studies. On the whole, 36 patients among 43 with invasion of the optic canal (83.7%) had preoperative visual dysfunction; on the other hand, none among 17 patients without tumor invasion of the optic canal had visual dysfunction. The surgical approaches according to the tumor location were as follows. A supraorbital-pterional approach was used in the 8 inferomedial tumors, in the 22 orbital apex tumors, and in 9/12 diffuse tumors; these last two types had concentric involvement of the optic canal. Three diffuse tumors with significant extension in the infratemporal fossa were operated on via a frontotemporal-orbitozygomatic approach. A wide decompression of the optic canal was performed in all cases, excepting in two inferomedial tumors without optic canal invasion. The 18 patients with lateral tumors were approached via a lateral orbitocranial approach, including removal of the sphenoid wing and lateral orbital wall without bone flap; the resection of the lateral aspect of the optic canal was performed in the 3 cases with canal invasion. Postoperative improvement of the visual function was observed in 18 of 36 cases with visual dysfunction (50%). The rate of visual improvement was significantly higher in cases with lateral involvement (3/3 or 100%) than in those with concentric involvement of the optic canal (11/27 or 40.7%). CONCLUSION: The invasion of the optic canal by the tumor is the main reason of visual dysfunction in patients with spheno-orbital meningiomas. A wide opening of the optic canal must be performed routinely in patients with orbital apex and diffuse orbital tumors, where there is concentric invasion of the optic canal wall. In these cases the supraorbital-pterional approach is the technique of choice. In selected cases with lateral intraorbital tumors and invasion of the lateral aspect of the optic canal the complete tumor resection coupled with good decompression of the optic nerve may be achieved via a less invasive lateral orbitocranial approach without craniotomy.