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Kalyvas A, Koutsarnakis C, Komaitis S, Karavasilis E, Christidi F, Skandalakis GP, Liouta E, Papakonstantinou O, Kelekis N, Duffau H, Stranjalis G. Mapping the human middle longitudinal fasciculus through a focused anatomo-imaging study: shifting the paradigm of its segmentation and connectivity pattern. Brain Struct Funct 2019; 225:85-119. [PMID: 31773331 DOI: 10.1007/s00429-019-01987-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 11/14/2019] [Indexed: 12/11/2022]
Abstract
Τhe middle longitudinal fasciculus (MdLF) was initially identified in humans as a discrete subcortical pathway connecting the superior temporal gyrus (STG) to the angular gyrus (AG). Further anatomo-imaging studies, however, proposed more sophisticated but conflicting connectivity patterns and have created a vague perception on its functional anatomy. Our aim was, therefore, to investigate the ambiguous structural architecture of this tract through focused cadaveric dissections augmented by a tailored DTI protocol in healthy participants from the Human Connectome dataset. Three segments and connectivity patterns were consistently recorded: the MdLF-I, connecting the dorsolateral Temporal Pole (TP) and STG to the Superior Parietal Lobule/Precuneus, through the Heschl's gyrus; the MdLF-II, connecting the dorsolateral TP and the STG with the Parieto-occipital area through the posterior transverse gyri and the MdLF-III connecting the most anterior part of the TP to the posterior border of the occipital lobe through the AG. The lack of an established termination pattern to the AG and the fact that no significant leftward asymmetry is disclosed tend to shift the paradigm away from language function. Conversely, the theory of "where" and "what" auditory pathways, the essential relationship of the MdLF with the auditory cortex and the functional role of the cortical areas implicated in its connectivity tend to shift the paradigm towards auditory function. Allegedly, the MdLF-I and MdLF-II segments could underpin the perception of auditory representations; whereas, the MdLF-III could potentially subserve the integration of auditory and visual information.
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Affiliation(s)
- Aristotelis Kalyvas
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece.,Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece.,Department of Anatomy, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Christos Koutsarnakis
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece. .,Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece. .,Department of Anatomy, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
| | - Spyridon Komaitis
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece.,Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece.,Department of Anatomy, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Efstratios Karavasilis
- Second Department of Radiology, Attikon Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Foteini Christidi
- First Department of Neurology, Aeginition Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Georgios P Skandalakis
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece.,Department of Anatomy, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Evangelia Liouta
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece.,Hellenic Center for Neurosurgical Research, "PetrosKokkalis", Athens, Greece
| | - Olympia Papakonstantinou
- Second Department of Radiology, Attikon Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Nikolaos Kelekis
- Second Department of Radiology, Attikon Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Hugues Duffau
- Department of Neurosurgery, Montpellier University Medical Center, Gui de Chauliac Hospital, Montpellier, France
| | - George Stranjalis
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece.,Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece.,Hellenic Center for Neurosurgical Research, "PetrosKokkalis", Athens, Greece
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Koutsarnakis C, Kalyvas AV, Komaitis S, Liakos F, Skandalakis GP, Anagnostopoulos C, Stranjalis G. Defining the relationship of the optic radiation to the roof and floor of the ventricular atrium: a focused microanatomical study. J Neurosurg 2018; 130:1728-1739. [PMID: 29726766 DOI: 10.3171/2017.10.jns171836] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 10/30/2017] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The authors investigated the specific topographic relationship of the optic radiation fibers to the roof and floor of the ventricular atrium because the current literature is ambiguous. METHODS Thirty-five normal, adult, formalin-fixed cerebral hemispheres and 30 focused MRI slices at the level of the atrium were included in the study. The correlative anatomy of the optic radiation with regard to the atrial roof and floor was investigated in 15 specimens, each through focused fiber microdissections. The remaining 5 hemispheres were explored with particular emphasis on the trajectory of the collateral sulcus in relation to the floor of the atrium. In addition, the trajectory of the collateral sulcus was evaluated in 30 MRI scans. RESULTS The atrial roof was observed to be devoid of optic radiations in all studied hemispheres, whereas the atrial floor was seen to harbor optic fibers on its lateral part. Moreover, the trajectory of the intraparietal sulcus, when followed, was always seen to correspond to the roof of the atrium, thus avoiding the optic pathway, whereas that of the collateral sulcus was found to lead to either the lateral atrial floor or outside the ventricle in 88% of the cases, therefore hitting the visual pathway. CONCLUSIONS Operative corridors accessing the ventricular atrium should be carefully tailored through detailed preoperative planning and effective use of intraoperative navigation to increase patient safety and enhance the surgeon's maneuverability. The authors strongly emphasize the significance of accurate anatomical knowledge.
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Affiliation(s)
- Christos Koutsarnakis
- 1Athens Microneurosurgery Laboratory, Evangelismos Hospital
- 2Department of Neurosurgery, Evangelismos Hospital, and
| | - Aristotelis V Kalyvas
- 1Athens Microneurosurgery Laboratory, Evangelismos Hospital
- 2Department of Neurosurgery, Evangelismos Hospital, and
| | - Spyridon Komaitis
- 1Athens Microneurosurgery Laboratory, Evangelismos Hospital
- 2Department of Neurosurgery, Evangelismos Hospital, and
| | - Faidon Liakos
- 1Athens Microneurosurgery Laboratory, Evangelismos Hospital
| | - Georgios P Skandalakis
- 1Athens Microneurosurgery Laboratory, Evangelismos Hospital
- 3Department of Anatomy
- 5Hellenic Center for Neurosurgical Research "Petros Kokkalis," Athens, Greece
| | | | - George Stranjalis
- 1Athens Microneurosurgery Laboratory, Evangelismos Hospital
- 2Department of Neurosurgery, Evangelismos Hospital, and
- 3Department of Anatomy
- 4Medical School, National and Kapodistrian University of Athens; and
- 5Hellenic Center for Neurosurgical Research "Petros Kokkalis," Athens, Greece
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