Atypical cerebral language dominance in a right-handed patient: An anatomoclinical study.
OBJECTIVE
Approximately 97% of the right-handers has left hemisphere language dominance. Within the language dominant hemisphere Broca's area is of crucial importance for a variety of linguistic functions. As a result, tumour resection in and around Broca's area is controversial. However, studies showed that by means of Direct Electrical Stimulation (DES) tumour resection in this region can be safely performed. We report unexpected anatomoclinical findings in a right-handed patient who underwent tumour resection in the left prefrontal lobe.


METHODS
Language functions in this right-handed patient were extensively examined in the pre-, intra-, and postoperative phase by means of a standardised battery of neurolinguistic and neurocognitive tests. Results obtained in the pre- and postoperative phase are compared. In addition, intraoperative DES findings and postoperative functional Magnetic Resonance Imaging (fMRI) and Diffusion Tensor Imaging (DTI) results are reported.


RESULTS
Tumour resection near Broca's area was safely performed since no positive language sites were found during intraoperative DES. Since no linguistic deficits occurred in the pre-, intra-, or postoperative phase, atypical language dominance was suspected. Neuropsychological investigations, however, disclosed permanent executive dysfunction. Postoperative fMRI and DTI confirmed right cerebral language dominance as well as a crossed cerebro-cerebellar functional link with the left cerebellar hemisphere.


CONCLUSIONS
Atypical right hemisphere language dominance in this right-handed patient is reflected by: (1) the total absence of language problems in the pre-, intra- and postoperative phase, (2) absence of positive stimulation sites during DES, (3) a clearly more pronounced arcuate fasciculus in the right cerebral hemisphere (DTI), (4) a crossed functional connection between the right cerebrum and the left cerebellum (fMRI). Two hypothetical explanations for the pattern of crossed cerebral language dominance are put forward: (1) preoperative brain plasticity mechanisms inducing a shift of language functions to the right hemisphere or (2) right hemisphere language dominance as a maturational variant. This case with atypical cerebral language dominance shows that although DES is the 'gold standard' to identify eloquent language regions and their pathways, fMRI and DTI are important adjuncts to guide surgery, to identify language lateralisation and to study anatomoclinical correlations.
Department of Clinical and Experimental Neurolinguistics, CLIN, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.
Elke
E
De Witte
Department of Radiology, Antwerp University Hospital, Wilrijkstraat 10, B-2650 Antwerp, Belgium; icoMetrix, Tervuursesteenweg 244, B-3001 Leuven, Belgium.
Wim
W
Van Hecke
Department of Neurosurgery, ZNA Middelheim General Hospital, Lindendreef 1, B-2020 Antwerp, Belgium.
Guido
G
Dua
Department of Radiology, ZNA Middelheim General Hospital, Lindendreef 1, B-2020 Antwerp, Belgium.
Didier
D
De Surgeloose
Department of Neurosurgery and Center for Neuroscience, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, B-1090 Brussels, Belgium.
Maarten
M
Moens
Department of Clinical and Experimental Neurolinguistics, CLIN, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium; VLAC (Vlaams Academisch Centrum), Advanced Studies Institute of the Royal Flemish Academy of Belgium for Sciences and the Arts, Brussels, Belgium; Department of Neurology & Memory Clinic, ZNA Middelheim General Hospital, Lindendreef 1, B-2020 Antwerp, Belgium. Electronic address: peter.marien5@telenet.be.
Peter
P
Mariën
D000328:Adult; D001931:Brain Mapping; D001932:Brain Neoplasms / Q000503:physiopathology / Q000523:psychology / Q000601:surgery; D056324:Diffusion Tensor Imaging; D004292:Dominance, Cerebral / Q000502:physiology*; D004599:Electric Stimulation Therapy; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D005910:Glioma / Q000503:physiopathology / Q000523:psychology / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D009483:Neuropsychological Tests; D019635:Neurosurgical Procedures; D012640:Seizures / Q000150:complications; D014145:Trail Making Test; D014888:Wechsler Scales
Atypical language dominance; Awake craniotomy; Broca's area; Crossed dominance; Direct Electrical Stimulation; Language mapping; fMRI