A case of aphasia due to temporobasal edema: Contemporary models of language anatomy are clinically relevant

Abstract

Background: Understanding the anatomy of language in the human brain is crucial for neurosurgical decision making and complication avoidance. The traditional anatomical models of human language, relying on relatively simple and rigid concepts of brain connectivity, cannot explain all clinical observations. The clinical case reported here illustrates the relevance of more recent concepts of language networks involving white matter tracts and their connections.

Case description: Postoperative edema of the ventral occipitotemporal cortex, where modern network models locate a crucial language hub, resulted in transient severe aphasia after a subtemporal approach. Both verbal comprehension and expression were lost. The resolution of edema was associated with complete recovery from phonetic and semantic dysfunction.

Conclusion: Complete aphasia due to a functional disturbance remote from the areas of Broca and Wernicke could be explained by contemporary neuroanatomical concepts of white matter connectivity. Knowledge of network-based models is relevant in brain surgery complication avoidance.

Keywords: Aphasia; Connectivity; Language; Networks; White matter tracts.

Figure 1:

The traditional Wernicke–Lichtheim model of language connectivity. The depicted connectivity permits serial, mainly unidirectional information processing. Semantic concepts are formed by higher associative systems distributed throughout the associative cortex, harboring conceptual representations of distinct modalities associated with a particular object.

Figure 2:

Preoperative magnetic resonance imaging (MRI); a: T1 + gadolinium, b: T2-fluid-attenuated inversion recovery (FLAIR), and asterisk: clival meningioma. Postoperative MRI, c and d, day 3, e, and f 1 year; T2-FLAIR. T: Temporal lobe. O: Occipital lobe.

Figure 3:

Diffusion tensor imaging tractography 4 years after surgery, fused with initial 2D postoperative fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) (syngo.via, Siemens, Munich, Germany). The ILF and inferior fronto-occipital fasciculus (IFOF) are part of the ventral stream and join posteriorly. The superior longitudinal fasciculus (SLF) represents the dorsal stream. (a-d): the reconstructed inferior longitudinal fasciculus (ILF) (white asterisk and green fibers) and posterior part of the IFOF, including their junction with the SLF (black asterisk and blue fibers), are depicted on craniocaudal axial FLAIR slices in relation to the temporobasal hypersignal. (e): 3D VRT reconstruction of the SLF, IFOF, and ILF in relation to the temporal FLAIR hypersignal (white star and lines, at the junction of the three tracts) on axial and sagittal images.