Visualization, navigation, augmentation. The ever-changing perspective of the neurosurgeon.

Introduction: The evolution of neurosurgery coincides with the evolution of visualization and navigation. Augmented reality technologies, with their ability to bring digital information into the real environment, have the potential to provide a new, revolutionary perspective to the neurosurgeon. Research question: To provide an overview on the historical and technical aspects of visualization and navigation in neurosurgery, and to provide a systematic review on augmented reality (AR) applications in neurosurgery. Material and methods: We provided an overview on the main historical milestones and technical features of visualization and navigation tools in neurosurgery. We systematically searched PubMed and Scopus databases for AR applications in neurosurgery and specifically discussed their relationship with current visualization and navigation systems, as well as main limitations. Results: The evolution of visualization in neurosurgery is embodied by four magnification systems: surgical loupes, endoscope, surgical microscope and more recently the exoscope, each presenting independent features in terms of magnification capabilities, eye-hand coordination and the possibility to implement additional functions. In regard to navigation, two independent systems have been developed: the frame-based and the frame-less systems. The most frequent application setting for AR is brain surgery (71.6%), specifically neuro-oncology (36.2%) and microscope-based (29.2%), even though in the majority of cases AR applications presented their own visualization supports (66%). Discussion and conclusions: The evolution of visualization and navigation in neurosurgery allowed for the development of more precise instruments; the development and clinical validation of AR applications, have the potential to be the next breakthrough, making surgeries safer, as well as improving surgical experience and reducing costs.

Cerebellar mutism syndrome: the importance of preoperative language assessment.

Children undergoing surgical removal of tumors in the posterior cranial fossa can encounter a varied and complex constellation of neurological symptoms, called cerebellar mutism, defined as a disturbance in the planning and programming of motor language with preserved understanding, behavioral disorders such as inattention, visual-spatial disorganization, personality change, as well as ataxia and dysmetria. In the last years, several groups have been trying to establish risk factors or even predictive scores in order to be able at least in part to predict the appearance of speech disorders before surgery. We report on a child with pilocytic astrocytoma of the cerebellar vermis who had already been diagnosed with developmental linguistic delay two years earlier. This disorder initially worsened after surgery and later improved in the following 12 months. The aim of this paper is to emphasize the importance of preoperative neuropsychological evaluation. The present case, along with those reported in the literature, suggests that the risk of long-term cerebellar mutism is higher in children with preoperative speech disorders. In these patients a thorough assessment of cognitive and linguistic functions is therefore necessary to better evaluate the risk of cerebellar mutism after surgery.

Intramedullary spinal cord metastasis from an adenoid cystic carcinoma of the external auditory canal: case report.

BACKGROUND AND IMPORTANCE: Intramedullary spinal cord metastases (ISCMs) are rare and no cases of ISCM from an adenoid cystic carcinoma (ACC) of the external auditory canal (EAC) have been reported. CLINICAL PRESENTATION: We report a 54-year old man complaining backpain and worsening myelopathy. He had an ACC of the EAC resected years prior. A spinal MRI demonstrated a contrast-enhancing intramedullary lesion within the conus medullaris. The histopathological diagnosis of the patient was consistent with the patient's primary cancer. At 3 months follow-up, the neurological condition of the patient was unchanged. CONCLUSIONS: This is the first reported case of ISCM from a primary ACC of the EAC.

Acquisition of surgical skills for endoscopic ear and lateral skull base surgery: a staged training programme.

SUMMARY: Endoscopic ear surgery is radically changing the treatment of several middle and inner ear pathology, but its learning presents well-known manual and technical difficulties. The aim of this paper is be to present a training programme based on a modular model of increased difficulties. The experience from 2007 to 2016 at the University Hospital of Modena and University Hospital of Verona was reviewed and analysed for further considerations and to establish stages of training. The increasing experience of expert surgeons who deal with this kind of surgery represented the main guide to establish the steps and progression of training. In addition, the potential risk of damage of vascular structures or nerves represents fundamental criteria for progression toward higher levels. Some not-mandatory skills were also suggested for stage of difficulty. Five stages of training were deemed appropriate for progressive learning of endoscopic ear and lateral skull base surgery, ranging from simple middle and external ear procedures to surgery of inner ear and internal auditory canal. Mastering of each level is suggested before attempting procedures at a higher level, in particular for procedures involving lateral skull base. Standardisation and adoption of modular incremental training are expected to facilitate improvement of otolaryngologists and neurosurgeons starting with endoscopic middle ear and lateral skull base surgery. Adherence to such a programme during the growth phase may potentially decrease the rate of complications, making the training programme safer.

Expanded transcanal transpromontorial approach to the internal auditory canal and cerebellopontine angle: a cadaveric study.

The aim of this paper is to describe and evaluate the feasibility of an expanded endoscopic transcanal transpromotorial approach (ExpTTA) to the internal auditory canal and the cerebellopontine angle. To this end, we performed a cadaveric dissection study in September 2015. In total, 2 heads (4 sides) were dissected focusing on anatomical landmarks and surgical feasibility. Data from dissections were reviewed and analysed for further consideration. In all 4 sides of the cadavers the procedure was feasible. In all cadavers, it was necessary to extensively drill the temporo-mandibular joint and to calibrate the external ear canal to allow adequate room to manoeuver the instruments and optics and to comfortably access the cerebellopontine angle. In addition, thorough skeletonisation of the carotid artery and the jugular bulb were necessary for the same purpose. In conclusion, ExpTTA appeared to be successful to access the internal auditory canal and cerebellopontine angle region. Potential extensive and routine application of this type of approach in lateral skull base surgery will depend on the development of technology and surgical refinements and on the diffusion of skull base endoscopic skills among otolaryngologists and neurosurgical community.

Neurosurgical treatment of von Hippel-Lindau-associated hemangioblastomas: benefits, risks and outcome.

AIM: Von Hippel-Lindau (VHL) disease is a genetic syndrome predisposing to central nervous system (CNS) hemangioblastomas and several lesions in many organs. The cases of all VHL individuals operated on in the Neurosurgical Unit of Padua Hospital since year 2000 were reviewed in order to define which features lead to surgical treatment and to examine surgical outcome during postoperative follow-up. METHODS: The authors evaluated 20 VHL subjects (7 males and 13 females, age at surgery 32+/-10 years) who underwent 28 operations in order to remove 48 CNS hemangioblastomas and 1 endolymphatic sac tumor. Among the 49 resected lesions, 21 (42%) were cerebellar, 9 (18%) at brainstem, 19 (38%) spinal (7 cervical, 6 dorsal, 6 at cone-cauda level), and 1 (2%) endolymphatic sac tumor in the petrous bone. Patients were graduated according to Karnofsky Performance Status (KPS) at admission, at discharge and during the last follow up visit. Genetic testing revealing the presence of a VHL disease-causing mutation was a prerequisite for inclusion in the study. RESULTS: Nineteen individuals (95%) were symptomatic. Symptomatic hemangioblastomas were associated with a cyst or a syrinx in 22/27 circumstances (81%). Total removal, as confirmed by postoperative magnetic resonance imaging (MRI), was achieved in all but one lesion. Following surgery, at follow-up (38+/-20 months), patients improved their neurological status in 75% of cases, 20% remained stable and 5% worsened; 16 patients (80%) are able to carry on normal activity with or without minor symptoms, 3 patients require some grade of assistance, 1 patient died because of bronchopneumonia. CONCLUSION: VHL-associated hemangioblastomas generally affect a young adult population and can be successfully removed, either when symptomatic, or when they reach a critical volume. Microsurgery of hemangioblastomas has a favourable impact on survival and quality of life of VHL patients, although it is strongly influenced by preoperative conditions. Transient surgical complications are possible, particularly with brainstem and spinal cord hemangioblastomas.

Endoscopic treatment of hydrocephalus due to aneurysm of the vein of Galen: case report and literature review.

Aneurysms of the vein of Galen are uncommon vascular malformations. They are most frequently seen in infants and children, leading to heart failure and hydrocephalus. Exceptionally, they are detected in adults. Several theories have been proposed to explain hydrocephalus in these patients: obstruction of the cerebral aqueduct, impaired absorption of CSF after subarachnoid hemorrhage, passive ex-vacuo mechanism, or thrombosis of an aneurysm. Hydrocephalus has been treated mainly with cerebrospinal shunt procedures, but also direct surgery, radiosurgery and embolisation of the malformation have proved to be effective. We report the case of a partially thrombosed ectasia of the vein of Galen in a 44-year-old male, with huge hydrocephalus successfully treated with an endoscopic third ventriculostomy.

[Isolated oculomotor palsy disclosing multiple myeloma]. / Paralysie oculomotrice isolée révélatrice d'un myélome multiple.

Two cases of oculomotor nerves involvement as uncommon initial manifestation of a parasellar extramedullary plasmacytoma are reported. The first patient presented with an isolated left VI cranial nerve palsy; the second one had an incomplete left III cranial nerve palsy. In both cases clinical investigation and computed tomography revealed an intracranial plasmacytoma associated with multiple myeloma. It is important to underline the difference between an intracranial extramedullary plasmacytoma and a plasmacytoma associated with multiple myeloma. In fact the absence of a general associated illness should show a most favourable course.

[Traumatic internuclear ophthalmoplegia]. / Ophtalmoplégie internucléaire traumatique.

The authors report a case of traumatic internuclear ophthalmoplegia and discuss its pathophysiologic mechanism. Internuclear ophthalmoplegia due to head trauma is uncommon, though it may be more common than reported since signs and symptoms typically resolve over weeks to months, and in multiple trauma patients other serious injuries overshadow disturbances of eye movements. A lesion involving medial longitudinal fasciculus was found by magnetic resonance imaging in the early post-traumatic period; this lesion was not seen when routine X-ray computed tomography was performed at the time of injury, confirming that magnetic resonance scanning is definitely superior to computed tomography for evaluating internuclear ophthalmoplegia.