Neurosurgery department – surgery for pituitary and skull base adenomas

Since 2014, under the leadership of Professor Jouanneau and at the request of the Hospices Civils de Lyon, our Neurosurgery department has been created with a single objective: to bring together the know-how of different medical and surgical specialties to improve patient care. adults with intracranial tumors, particularly those of the base of the skull.



Dr Timothée JACQUESSON has been carrying out neurosurgery activity on brain and skull base tumors since 2013. After a medical thesis on new endoscopic and microsurgical approaches to the petroclival region, he carried out science thesis work, supported in 2018, on the development of tractography applied to the detection of the position of cranial nerves displaced by tumors. He is today continuing his research work towards the automation of post-processing of MRI data to promote the routine clinical use of tractography and its derived tools (HDR 2022). It also seeks to use high-resolution diffusion MRI to help guide the histological diagnosis and extract the characteristics of complex skull base tumors (implantation, consistency, vascularization, cleavability, fiber environment, etc.).

Since 2023, he has also been Professor of Anatomy at the University of Lyon 1 and Deputy Head of Department of the Cranial Tumor and Vascular Neurosurgery Department. He regularly supervises Masters and thesis students on these areas of research at the intersection of surgery, anatomy and imaging.


Research focus

  • Tractography of cerebral white fibers
  • New surgical approaches to the skull base
  • Advanced brain tumor surgery technique
  • Anatomy of the skull and brain
  • High resolution MRI


1. MR diffusion tractography of brain white matter tracts: an educational 3D stereoscopic overview for operative planning and mapping in brain surgery. 3D Video.

ANg S, Maldonado I, Destrieux C, Yeh F, Fernandez-Miranda J, Duffau H, Jacquesson T

Operative Neurosugery — Abstract


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No abstract available

2. Overcoming challenges of the human spinal cord tractography for routine clinical use: a review. 

Dauleac C, Frindel C, Mertens P, Jacquesson T, Cotton F.

Neuroradiology — Abstract


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The spinal cord (SC) is a dense network of billions of fibers in a small volume surrounded by bones that makes tractography difficult to perform. We aim to provide a review collecting all technical settings of SC tractography and propose the optimal set of parameters to perform a good SC tractography rendering. The MEDLINE database was searched for articles reporting “spinal cord” “tractography” in “humans”. Studies were selected only when tractography rendering was displayed and MRI acquisition and tracking parameters detailed. From each study, clinical context, imaging acquisition settings, fiber tracking parameters, region of interest (ROI) design, and quality of the tractography rendering were extracted. Quality of tractography rendering was evaluated by several objective criteria proposed herein. According to the reported studies, to obtain a good tractography rendering, diffusion tensor imaging acquisition should be performed with 1.5 or 3 Tesla MRI, in the axial plane, with > 20 directions; b value: 1000 s mm-2; right-left phase-encoding direction for cervical SC; isotropic voxel size; and no slice gap. Concerning the tracking process, it should be performed with determinist approach, fractional anisotropy threshold between 0.15 and 0.2, and curvature threshold of 40°. ROI design is an essential step for providing good tractography rendering, and their placement has to consider partial volume effects, magnetic susceptibility effects, and motion artifacts. The review reported herein highlights that successful SC tractography depends on many factors (imaging acquisition settings, fiber tracking parameters, and ROI design) to obtain a good SC tractography rendering.

Keywords: Diffusion tensor imaging; Fiber tracking; Review; Spinal cord; Tractography.

3. Cranial and Cerebral Anatomical Key Points for Neurosurgery: A New Educational Insight

Simon E, Beuriat PA, Delabar V, Jouanneau E, Fernandez-Miranda J, Jacquesson T 

Operative Neurosurgery — Abstract


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Background: The anatomy of both the skull and the brain offers many landmarks that could lead surgery. Cranial “craniometric” key points were described many years ago, and then, cerebral key points-along sulci and gyri-were detailed more recently for microneurosurgical approaches that can reach deep structures while sparing the brain. Nonetheless, this anatomic knowledge is progressively competed by new digital devices, such as imaging guidance systems, although they can be misleading.

Objective: To summarize cranial and sulcal key points and their related anatomic structures to renew their interest in modern neurosurgery and help surgical anatomy teaching.

Methods: After a literature review collecting anatomic key points of skull and brain, specimens were prepared and images were taken to expose skull and brain from lateral, superior, posterior, and oblique views. A high-definition camera was used, and images obtained were modified, superimposing both key points and underlying anatomic structures.

Results: From 4 views, 16 cranial key points were depicted: anterior and superior squamous point, precoronal and retrocoronal point, superior sagittal point, intraparietal point, temporoparietal point, preauricular point, nasion, bregma, stephanion, euryon, lambda, asterion, opisthocranion, and inion. These corresponded to underlying cerebral key points and relative brain parts: anterior and posterior sylvian point, superior and inferior rolandic point, supramarginal and angular gyri, parieto-occipital sulcus, and various meeting points between identifiable sulci. Stereoscopic views were also provided to help learning these key points.

Conclusion: This comprehensive overview of the cranial and sulcal key points could be a useful tool for any neurosurgeon who wants to check her/his surgic

4. Full tractography for detecting cranial nerves in position pre-operative planning of skull base surgery: technical note. 

Yeh F, Panesar S, Barrios J, Attyé A, Frindel C, Cotton F, Gardner P, Jouanneau E, Fernandez-Miranda J

J Neurosurg. — Abstract


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Objective: Diffusion imaging tractography has allowed the in vivo description of brain white matter. One of its applications is preoperative planning for brain tumor resection. Due to a limited spatial and angular resolution, it is difficult for fiber tracking to delineate fiber crossing areas and small-scale structures, in particular brainstem tracts and cranial nerves. New methods are being developed but these involve extensive multistep tractography pipelines including the patient-specific design of multiple regions of interest (ROIs). The authors propose a new practical full tractography method that could be implemented in routine presurgical planning for skull base surgery.

Methods: A Philips MRI machine provided diffusion-weighted and anatomical sequences for 2 healthy volunteers and 2 skull base tumor patients. Tractography of the full brainstem, the cerebellum, and cranial nerves was performed using the software DSI Studio, generalized-q-sampling reconstruction, orientation distribution function (ODF) of fibers, and a quantitative anisotropy-based generalized deterministic algorithm. No ROI or extensive manual filtering of spurious fibers was used. Tractography rendering was displayed in a tridimensional space with directional color code. This approach was also tested on diffusion data from the Human Connectome Project (HCP) database.

Results: The brainstem, the cerebellum, and the cisternal segments of most cranial nerves were depicted in all participants. In cases of skull base tumors, the tridimensional rendering permitted the visualization of the whole anatomical environment and cranial nerve displacement, thus helping the surgical strategy.

Conclusions: As opposed to classical ROI-based methods, this novel full tractography approach could enable routine enhanced surgical planning or brain imaging for skull base tumors.

Keywords: cranial nerves; planning; skull base; surgical technique; tractography; tumor.

5. Probabilistic Tractography to Predict the Position of Cranial Nerves Displaced by Skull Base Tumors: Value for Surgical Strategy Through a Case Series of 62 Patients.

Jacquesson T, Cotton F, Attyé A, Zaouche S, Tringali S, Bosc J, Robinson P, Jouanneau E, Frindel C. 

Neurosurgery — Abstract


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Background: Predicting the displacement of cranial nerves by tumors could make surgery safer and the outcome better. Recent advances in imaging and processing have overcome some of the limits associated with cranial nerve tractography, such as spatial resolution and fiber crossing. Among others, probabilistic algorithms yield to a more accurate depiction of cranial nerve trajectories.

Objective: To report how cranial nerve probabilistic tractography can help the surgical strategy in a series of various skull base tumors.

Methods: After distortion correction and region of interest seeding, a probabilistic tractography algorithm used the constrained spherical deconvolution model and attempted the reconstruction of cranial nerve trajectories in both healthy and displaced conditions.

Results: Sixty-two patients were included and presented: vestibular schwannomas (n = 33); cerebellopontine angle meningiomas (n = 15); arachnoid or epidermoid cysts (n = 6); cavernous sinus and lower nerves schwannomas (n = 4); and other tumors (n = 4). For each patient, at least one ‘displaced’ cranial nerve was not clearly identified on classical anatomical MRI images. All 372 cranial nerves were successfully tracked on each healthy side; among the 175 cranial nerves considered ‘displaced’ by tumors, 152 (87%) were successfully tracked. Among the 127 displaced nerves of operated patients (n = 51), their position was confirmed intraoperatively for 118 (93%) of them. Conditions that led to tractography failure were detailed. On the basis of tractography, the surgical strategy was adjusted for 44 patients (71%).

Conclusion: This study reports a cranial nerve probabilistic tractography pipeline that can: predict the position of most cranial nerves displaced by skull base tumors, help the surgical strategy, and thus be a pertinent tool for future routine clinical application.

Keywords: Cranial nerves; Diffusion imaging; Tractography; Tumors.

6. Overcoming Challenges of Cranial Nerve Tractography: A Targeted Review.

Jacquesson T, Frindel C, Kocevar G, Berhouma M, Jouanneau E, Attyé A, Cotton F

Neurosurgery— Abstract


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Background: Diffusion imaging tractography caught the attention of the scientific community by describing the white matter architecture in vivo and noninvasively, but its application to small structures such as cranial nerves remains difficult. The few attempts to track cranial nerves presented highly variable acquisition and tracking settings.

Objective: To conduct and present a targeted review collecting all technical details and pointing out challenges and solutions in cranial nerve tractography.

Methods: A “targeted” review of the scientific literature was carried out using the MEDLINE database. We selected studies that reported how to perform the tractography of cranial nerves, and extracted the following: clinical context; imaging acquisition settings; tractography parameters; regions of interest (ROIs) design; and filtering methods.

Results: Twenty-one published articles were included. These studied the optic nerves in suprasellar tumors, the trigeminal nerve in neurovascular conflicts, the facial nerve position around vestibular schwannomas, or all cranial nerves. Over time, the number of MRI diffusion gradient directions increased from 6 to 101. Nine tracking software packages were used which offered various types of tridimensional display. Tracking parameters were disparately detailed except for fractional anisotropy, which ranged from 0.06 to 0.5, and curvature angle, which was set between 20° and 90°. ROI design has evolved towards a multi-ROI strategy. Furthermore, new algorithms are being developed to avoid spurious tracts and improve angular resolution.

Conclusion: This review highlights the variability in the settings used for cranial nerve tractography. It points out challenges that originate both from cranial nerve anatomy and the tractography technology, and allows a better understanding of cranial nerve tractography.

7. Which routes for petroclival tumors? A comparison between the anterior expanded endoscopic endonasal approach and lateral or posterior routes. 

Jacquesson T, Berhouma M, Tringali S, Jouanneau E.

World Neurosurg. — Abstract


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Objective: Petroclival tumors remain a surgical challenge. Classically, the retrosigmoid approach (RSA) has long been used to reach such tumors, whereas the anterior petrosectomy (AP) has been proposed to avoid crossing cranial nerves. More recently, the endoscopic endonasal approach has been “expanded” (i.e., EEEA) to the petroclival region. We aimed to compare these 3 approaches to help in the surgical management of petroclival tumors.

Methods: Petroclival approaches were performed on 5 specimens after they were prepared with formaldehyde colored via latex injection.

Results: The EEEA provides a simple straightforward route to the clivus, but reaching the petrous apex requires the surgeon to circumvent the internal carotid artery either via a medial transclival, an inferior transpterygoid, or a lateral variant through the Meckel’s cave. In contrast, the AP offers a narrow direct superolateral access to the petroclival region crossed by the trigeminal nerve. Finally, the RSA provides a wide simple and quick exposure of the cerebellopontine angle, but access to the petroclival region needs the surgeon to deal with the V(th) to XI(th) cranial nerves.

Discussion/conclusion: The EEEA should be preferred for extradural midline tumors (chordomas, chondrosarcomas) or for cystic lesions when drainage is essential. The AP could be optimal for the radical removal of intradural vascularized tumors (meningiomas) with intrapetrous or supratentorial extensions. The RSA retains an advantage for small or cystic tumors near the internal acoustic meatus. The skull base surgeon has to master all of these routes to choose the more appropriate one according to the surgical objective, the tumor characteristics, and the patient’s medical status.

Keywords: Endonasal; Endoscopy; Petroclival; Petrosectomy; Petrous apex; Skull base.

8. Anatomic comparison of anterior petrosectomy versus the expanded endoscopic endonasal approach: interest in petroclival tumors surgery.

Jacquesson T, Simon E, Berhouma M, Jouanneau E.

Surg Radiol Anat. — Abstract


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Purpose: Since the petroclival region is deep-seated with close neurovascular relationships, the removal of petroclival tumors still represents a fascinating surgical challenge. Although the classical anterior petrosectomy (AP) offers a meaningful access to this petroclival region, the expanded endoscopic endonasal approach (EEEA) recently leads to overcome difficulties from trans-cranial approaches. Herein, we present an anatomic comparison of AP versus EEEA. We aim to describe the limits of these both approaches helping the choice of the optimal surgical route for petroclival tumors.

Methods: Six fresh cadaveric heads were harvested and injected with colored latex. Each approach was step-by-step detailed until its final surgical exposure.

Results: The AP provided a narrow direct supero-lateral access to the petroclival area that can also reach the cavernous sinus, the retrochiasmatic region and perimesencephalic cisterns. However, this corridor anterior to the internal acoustic meatus passed on each side of the trigeminal nerve. Moreover, tumor extensions toward the foramen jugularis, inside the clivus or behind the internal acoustic meatus were difficult to control. The EEEA brought a straightforward access to the clivus but the petrous apex was hidden behind the internal carotid artery. Several variants were described: a medial transclival, a lateral through the Meckel’s cave and an inferior trans-pterygoid route. Elsewhere, tumor extension behind the internal acoustic meatus or above the tentorium could not be satisfactorily assessed.

Discussion and conclusion: PA and EEEA have their own limits in reaching the petroclival region in accordance with the tumor characteristics. The AP should be preferred for radical removal of middle-sized petrous apex intradural tumors like meningiomas. The EEEA would be of interest for extradural midline tumors like chordomas or for petrous apex cysts drainage.

Keywords: Endonasal; Endoscopy; Petroclival; Petrosectomy; Skull base.

9.Stereoscopic three-dimensional visualization: interest for neuroanatomy teaching in medical school

Jacquesson T, Simon E, Dauleac C, Margueron L, Robinson P, Mertens P.

Surg Radiol Anat. — Abstract


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Purpose: The anatomy of both the brain and the skull is particularly difficult to learn and to teach. Since their anatomical structures are numerous and gathered in a complex tridimensional (3D) architecture, classic schematical drawing or photography in two dimensions (2D) has difficulties in providing a clear, simple, and accurate message. Advances in photography and computer sciences have led to develop stereoscopic 3D visualization, firstly for entertainment then for education. In the present study, we report our experience of stereoscopic 3D lecture for neuroanatomy teaching to early medical school students.

Methods: High-resolution specific pictures were taken on various specimen dissections in the Anatomy Laboratory of the University of Lyon, France. Selected stereoscopic 3D views were displayed on a large dedicated screen using a doubled video projector. A 2-h stereoscopic neuroanatomy lecture was given by two neuroanatomists to third-year medicine students who wore passive 3D glasses. Setting up lasted 30 min and involved four people. The feedback from students was collected and analyzed.

Results: Among the 483 students who have attended the stereoscopic 3D lecture, 195 gave feedback, and all (100%) were satisfied. Among these, 190 (97.5%) reported a better knowledge transfer of brain anatomy and its 3D architecture. Furthermore, 167 (86.1%) students felt it could change their further clinical practice, 179 (91.8%) thought it could enhance their results in forthcoming anatomy examinations, and 150 (76.9%) believed such a 3D lecture might allow them to become better physicians. This 3D anatomy lecture was graded 8.9/10 a mean against 5.9/10 for previous classical 2D lectures.

Discussion-conclusion: The stereoscopic 3D teaching of neuroanatomy made medical students enthusiastic involving digital technologies. It could improve their anatomical knowledge and test scores, as well as their clinical competences. Depending on university means and the commitment of teachers, this new tool should be extended to other anatomical fields. However, its setting up requires resources from faculties and its impact on clinical competencies needs to be objectively assessed.

Keywords: Anatomy; Pedagogy; Stereoscopy; Teaching; Tridimensional.

10.The 360 photography: a new anatomical insight of the sphenoid bone. Interest for anatomy teaching and skull base surgery

Jacquesson T, Mertens P, Berhouma M, Jouanneau E, Simon E.

Surg Radiol Anat. — Abstract


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Skull base architecture is tough to understand because of its 3D complex shape and its numerous foramen, reliefs or joints. It is especially true for the sphenoid bone whom central location hinged with most of skull base components is unique. Recently, technological progress has led to develop new pedagogical tools. This way, we bought a new real-time three-dimensional insight of the sphenoid bone that could be useful for the teacher, the student and the surgeon. High-definition photography was taken all around an isolated dry skull base bone prepared with Beauchêne’s technique. Pictures were then computed to provide an overview with rotation and magnification on demand. From anterior, posterior, lateral or oblique views and from in out looks, anatomical landmarks and subtleties were described step by step. Thus, the sella turcica, the optic canal, the superior orbital fissure, the sphenoid sinus, the vidian canal, pterygoid plates and all foramen were clearly placed relative to the others at each face of the sphenoid bone. In addition to be the first report of the 360 Photography tool, perspectives are promising as the development of a real-time interactive tridimensional space featuring the sphenoid bone. It allows to turn around the sphenoid bone and to better understand its own special shape, numerous foramen, neurovascular contents and anatomical relationships. This new technological tool may further apply for surgical planning and mostly for strengthening a basic anatomical knowledge firstly introduced.

Keywords: Anatomy; Education; Photography; Skull base; Sphenoid bone.