Juan C. Fernandez-Miranda, MD

• Surgical Neuroanatomy Lab:

During the last year, Dr. Fernandez-Miranda completed, or has ongoing, several research projects at the Surgical Neuroanatomy Lab, including:

1) Endoscopic Endonasal Middle Clinoidectomy: Anatomical, Radiological, and Technical Note.

In this anatomical, radiological, and technical note, Dr. Fernandez-Miranda aims to introduce the importance of the middle clinoid when performing endonasal sellar/parasellar/suprasellar surgery. Here, he combines the knowledge obtained in the surgical neuroanatomy lab, neuroradiology suite, and in the operating room to illustrate the endonasal surgical anatomy of the middle clinoid and describe the anatomical and technical nuances for middle clinoid removal. (Accepted for publication in Neurosurgery.)

2) Anatomical and Surgical Compartments of the Cavernous Sinus

In this anatomical and technical report, Dr. Fernandez-Miranda introduces a different perspective of the cavernous sinus anatomy that is surgically relevant when performing endonasal pituitary surgery. He divides the cavernous sinus in four distinct compartments in relation to the intracavernous ICA. Each compartment has distinct boundaries, dural and neurovascular relationships, and surgical implications. Pre- and post-operative magnetic resonance imaging (MRI) of 138 pituitary adenomas with confirmed cavernous sinus invasion were studied to report the frequency of invasion of each compartment as well as the degree of tumor resection and complications at each compartment.

3) Endoscopic Endonasal Superomedial Orbitectomy: Anatomical and Technical Note.

In this study, Dr. Fernandez-Miranda presents a modification of the standard endoscopic endonasal transethmoidal approach to the anterior cranial base with the incorporation of a maximum bilateral superomedial orbitectomy. Here, he completes an anatomical study aiming to investigate how far lateral can expose the anterior skull base with this modified approach, and he analyzes the safety, efficacy, and technical nuances of the procedure in a series of 11 patients. 

4) Endoscopic Endonasal Surgical Anatomy and Classification of the Eustachian Tube

With the expansion of the endoscopic endonasal approaches in the coronal plane to reach the middle fossa and infratemporal space, the role of the ET in endonasal skull base surgery has become critical. The aim of this study is to describe the surgical anatomy of the ET and to present a novel segmental classification of the ET that has proven useful when applied into surgery.

5) Endoscopic Endonasal Transcavernous Posterior Clinoidectomy for Petroclival Meningiomas. Anatomical and Technical Note.

Here, Dr. Fernandez-Miranda describes a surgical variant of the endonasal posterior clinoidectomy approach, which does not require full pituitary transposition and takes advantage of the natural corridor provided by the cavernous sinus to get access to the posterior clinoid. The aim of this report is to detail the surgical anatomy and technical nuances of the endonasal transcavernous posterior clinoidectomy approach and to illustrate its clinical application for the resection of petroclival meningiomas. 

• High Definition Fiber Tractography (HDFT) Research Program:

During the 2011-12 course the HDFT program at the Surgical Neuroanatomy lab has been very active. These are the main ongoing research initiatives:

1) Anatomy of the fiber tracts in the human brain combining HDFT and fiber microdissection techniques: The “Pittsburgh Human Connectome Project.”

Dr. Fernandez-Miranda has recently published in Cerebral Cortex an investigation about the Middle Longitudinal Fascicle, a poorly known fiber tract that he has now described with greater detail and more accurately than previous descriptions. He has completed a study on the Arcuate Fascicle and its laterality and segmentation, and is completing research on the Superior Longitudinal Fascicle and the Superior Fronto-Occipital Tract. 

2) Neurosurgical applications of HDFT

Dr. Fernandez-Miranda has completed more than 50 HDFT studies in neurosurgery
patients. He has evaluated, from a qualitative and quantitative perspective, the impact of brain lesions in the structure of the fiber tracts, describing differential patterns of fiber tract damage secondary to the type of brain lesion. His efforts have been published in Neurosurgery as he continues expanding the surgical applications of HDFT. 

3) Validation of High-Definition Fiber Tracking on an Animal Model

High-Definition Fiber Tractography (HDFT) has been used to analyze white matter connections in multiple clinical settings, but it has not been validated by histo-pathologic means. Dr. Fernandez-Miranda study aims to develop an animal model for validation of HDFT white matter damage assessment. He will complete pre-intervention diffusion imaging, and immediately after performing fiber disruption damage in one hemisphere, and fiber displacement damage in the contralateral hemisphere. The post-intervention diffusion imaging will evaluate the structural damage to the fiber tracts. Finally, post-mortem studies will be completed both using the fiber dissection technique and histological studies, aiming to validate the radiological results.

4) HDFT in Aphasia patients: Neuroanatomy and neuroplasticity of the language system

The purpose of the proposed research is to employ HDFT and current functional models of word production to establish more detailed brain-behavior correspondences in aphasia and its treatment than has thus far been possible. Dr. Fernandez-Miranda aims to determine whether targeted behavioral treatment induces structural neuroplastic changes in corresponding subtracts of the Arcuate Fascicle.

5) White matter changes in Huntington Disease

This is an ongoing longitudinal study aiming to describe the fiber tract anomalies in HD patients, correlate these anomalies with the neuropsychological exam, and evaluate changes in the fiber tracts at 6 and 12 months.