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Intraoperative short-term functional reshaping of cortical motor networks studied using direct electrical stimulations
NemoImage
11, Number
5, 2000,
Part 2 of 2 Parts 10
Eat@@
SENSORIMOTOR
Intraoperative short-term functional reshaping of cortical motor networks studied using direct electrical stimulations Hugues Duffau, Jean-Pierre Sichez Department of Neurosurgery 1, H6pital de la Salp&tritre, Paris, France OBJECTIVE Although dynamic sensorimotor cortical plasticity for functional reorganization in humans has aheady been illustrated using neurofunctional imaging methods in cases of congenital or acquired lesions (1,2), mechanisms of compensation still remain obscure. The authors report the tirst observation of a real-time intraoperative evidence of a retrocentral redistribution of motor areas, with an unmasking of preeentral rednnda.nt motor eloquent sites, respectively before and after surgical removal of a precentral angioma, using direct electrical stimnlations. PATENT
AlW
METHOD
A 39-year old tight-handed man presented with seizures, and a normal neurological examination. A left precentral angioma was diagnosed on angiography and MRI. Embolization was first performed: because of the unability to obtain a complete obliteration (80% only), stit’gery was then decided. The surgical procedure was performed using intraoperative motor brain mapping with direct electrical stimulations (biphasic current, 1 msec/phase, 60 Hz, 16 mA, OCSl Radionics*), already described by the authors (3). RESULTS Only three functional motor sites for arm and hand movements were detected before angioma removal, and were found behind the central sulcus defined using anatomical criteria previously reported (4), thus separated from the angioma by a gyms without any response to the stimulations. After the lesion resection, the same 3 motor areas were stimulated with the same electrical parameters, inducing the same movements, showing that the pre- and post-removal maps were reproducible. Moreover, 2 new functional sires were also detected, eliciting the same hand and arm motor responses, but located in the gyrus in front of the previous eloquent region (i.e. the gytus corresponding to the supposed precentral area using anatomical criterias), that showed no motor response to the stimulations before angioma resection. The patient presented a mild and transient postoperative arm motor deficit, with a complete recovery in one month. CONCLUSIONS This observation gives some evidence in favour of the existence of brain plasticity. First, a large-scale plasticity of the motor function behind the central sulcus due to congenital precentral angioma is showed. Second, the brain ability of short-term unmasking of precentral motor sites after lesion resection is observed, likely explained by a phenomenon of local inhibition suppression. Third, redundant pre- and post-central motor areas for the same function have been detected, suggesting the existence of multiple cortical representation for the same function, and that the central sulcus does not simply divide motor and sensory functions. REFERENCES 1. 2. 3. 4.
Maldjian J, Atlas SW, Howard RS, et al. J Neurosurg 1996;84:477-483 Lewine JD, Astur RS, Davies LE, et al. Radiology 1994;190:93-96 Duffau H, Capelle L, Sichez JP, et al. Acta Neurochir (Wien) 1999;141:1157-1167 Yousry TA, Schmidt UD, Alkhadi H, et al. Brain 1997;120:141-157
S825
11, Number
5, 2000,
Part 2 of 2 Parts 10
Eat@@
SENSORIMOTOR
Intraoperative short-term functional reshaping of cortical motor networks studied using direct electrical stimulations Hugues Duffau, Jean-Pierre Sichez Department of Neurosurgery 1, H6pital de la Salp&tritre, Paris, France OBJECTIVE Although dynamic sensorimotor cortical plasticity for functional reorganization in humans has aheady been illustrated using neurofunctional imaging methods in cases of congenital or acquired lesions (1,2), mechanisms of compensation still remain obscure. The authors report the tirst observation of a real-time intraoperative evidence of a retrocentral redistribution of motor areas, with an unmasking of preeentral rednnda.nt motor eloquent sites, respectively before and after surgical removal of a precentral angioma, using direct electrical stimnlations. PATENT
AlW
METHOD
A 39-year old tight-handed man presented with seizures, and a normal neurological examination. A left precentral angioma was diagnosed on angiography and MRI. Embolization was first performed: because of the unability to obtain a complete obliteration (80% only), stit’gery was then decided. The surgical procedure was performed using intraoperative motor brain mapping with direct electrical stimulations (biphasic current, 1 msec/phase, 60 Hz, 16 mA, OCSl Radionics*), already described by the authors (3). RESULTS Only three functional motor sites for arm and hand movements were detected before angioma removal, and were found behind the central sulcus defined using anatomical criteria previously reported (4), thus separated from the angioma by a gyms without any response to the stimulations. After the lesion resection, the same 3 motor areas were stimulated with the same electrical parameters, inducing the same movements, showing that the pre- and post-removal maps were reproducible. Moreover, 2 new functional sires were also detected, eliciting the same hand and arm motor responses, but located in the gyrus in front of the previous eloquent region (i.e. the gytus corresponding to the supposed precentral area using anatomical criterias), that showed no motor response to the stimulations before angioma resection. The patient presented a mild and transient postoperative arm motor deficit, with a complete recovery in one month. CONCLUSIONS This observation gives some evidence in favour of the existence of brain plasticity. First, a large-scale plasticity of the motor function behind the central sulcus due to congenital precentral angioma is showed. Second, the brain ability of short-term unmasking of precentral motor sites after lesion resection is observed, likely explained by a phenomenon of local inhibition suppression. Third, redundant pre- and post-central motor areas for the same function have been detected, suggesting the existence of multiple cortical representation for the same function, and that the central sulcus does not simply divide motor and sensory functions. REFERENCES 1. 2. 3. 4.
Maldjian J, Atlas SW, Howard RS, et al. J Neurosurg 1996;84:477-483 Lewine JD, Astur RS, Davies LE, et al. Radiology 1994;190:93-96 Duffau H, Capelle L, Sichez JP, et al. Acta Neurochir (Wien) 1999;141:1157-1167 Yousry TA, Schmidt UD, Alkhadi H, et al. Brain 1997;120:141-157
S825