Brain Mapping and Operating Safely in Eloquent Cortex One of the greatest challenges in neurosurgery is surgeons who encounter these cases. An outline safely removing lesions in and around eloquent of the advantages and the limitations of each cortex. Considerations starting with operative tool as well as treatment algorithms for applica- indications through preoperative functional map- tions in specifi c clinical circumstances creates a ping, intraoperative mapping, imaging, and func- clear guide to this most complex of neurosurgi- tional monitoring, to decisions on when to stop cal problem. Clinical case examples are linked surgery are intrinsic and essential to operating to intraoperative photos and videos showing safely in eloquent cortex. Mastering the advan- hands on applications of cortical mapping in tages and limitations of each of these steps can eloquent cortex in various pathologies. In this lead to a practical and safe application of the vari- textbook, the practitioner will fi nd a ready ous tools available to the operating neurosurgeon guide to navigating the practical decisions that in cases involving eloquent cortex. are commonly faced when operating in elo- This book provides the latest update of the quent cortex. most practical information available to neuro- © Springer International Publishing Switzerland 2016 219 R.W. Byrne (ed.), Functional Mapping of the Cerebral Cortex, DOI 10.1007/978-3-319-23383-3 Index A electrical stimulation , 79 AAA approach. See Asleep–awake–asleep electrocorticography/cortical mapping , 86 (AAA) approach endotracheal tube and mechanical ventilation , 79 Abrasion of superfi cial cortical layers , 9 fatal cardiac arrhythmias , 79 Alexia , 161 , 192 human cerebral cortex , 79 American Clinical Neurophysiology Society (ACNS) , 115 ice-cold saline , 87 American Society of Electroneurodiagnostic ICP , 82 Technologists (ASET) , 115 inhalational agents , 82 Analgesia and sedation intraoperative neurological testing , 80 intravenous , 84–85 long-acting drug bupivacaine , 80 nerve blocks mannitol , 82 auriculotemporal , 83 nicardipine , 82 cutaneous sensory innervation , 83 open-drop technique , 79 epinephrine , 83 patient , 86 greater occipital , 83 preoperative evaluation and preparation , 80–81 intraoperative pain control , 83 properties , 79 lesser occipital , 84 seizure focus resections , 79 levobupivacaine , 83 short-acting intravenous barbiturates , 79 ropivocaine , 83 sterile fi eld , 87 supraorbital , 83 vasodilatory effect , 82 supratrochlear , 83 vasopressors , 82 zygomaticotemporal , 83 Anterior central convolutions , 7 optimal balance , 83 Arcuate fasciculus (AF) , 51 . See also Superior pain medication requirement , 83 longitudinal fasciculus (SLF) Analog-to-digital converter (ADC) , 14 Asleep–awake–asleep (AAA) approach Anesthesia anesthetic method , 88 AAA approach , 80 , 88 , 89 dexmedetomidine , 88 airway management strategy intraoperative brain mapping , 88 glidescope/fi ber-optic bronchoscope , 82 LMA/nasotracheal general anesthesia , 88 LMA/ETT , 81 MAC , 88 nasal cannula/facemask , 81 midazolam and fentanyl , 88 oxygenation and ventilation , 81 remifentanil , 88 propofol , 82 sedation level , 80 , 88 sniffi ng position , 82 Auditory evoked potentials (AEPs) , 13 awake craniotomy , 80 , 86 Autoradiography awake with regional scalp approach , 87 , 88 amino acids , 182 baseline speech and motor functions , 86 rhesus monkey, frontal and parietal lobes , 187 blood pressure , 82 spherical deconvolution , 189 cerebral perfusion , 82 Aversive head motion , 7 chloroform , 79 Awake craniotomy. See also Anesthesia cocaine , 80 cortical mapping/resection of lesion , 78 cortical mapping technique , 79 dura opening , 78 coughing and sneezing , 82 electrophysiological testing , 78 drug administration , 79 induction , 78 © Springer International Publishing Switzerland 2016 221 R.W. Byrne (ed.), Functional Mapping of the Cerebral Cortex, DOI 10.1007/978-3-319-23383-3 222 Index Awake craniotomy. See also Anesthesia (cont.) Compound muscle action potentials (CMAPs) , 125 neuroanesthesia , 78 Contralateral paralysis , 1 post-induction , 78 Cortex preoperative holding area , 78 corticospinal tract and arcuate fasciculus , 39 workfl ow stages , 79 eloquent , 24 Axonologists , 12 geniculocalcarine pathway , 39 lobar resection , 24 neuronavigation , 23 , 39 B safe to resect , 23 Bipolar stimulator , 70 , 72 , 73 subpial Blood oxygen level-dependent (BOLD) fMRI , 41 , 42 , and endopial resection , 23 4 5 , 4 6 , 4 8 gyral emptying , 24 Brain electrical activity recording sulcal and gyral anatomy , 23 AEPs , 13 vascular territory , 24 anesthetic agents , 13 white matter pathways , 23 axonologists , 12 Cortical and subcortical stimulation commercial availability, digital computers , 14 intraoperative cortical stimulation , 11 bipolar electrodes , 211 CRO , 12–14 Broca’s area, motor speech , 210 DC recordings in epilepsy , 15 fMRI , 210 EEG (see Electroencephalography (EEG)) functional neuroimaging , 210 electronic era in electrophysiology , 12 functional regions and pathways , 210 mirror galvanometer , 12 hemispheric gliomas , 209 , 210 MN , 15 leg motor cortex , 212 motor cortex , 15 motor and language mapping , 211 oscilloscope technique , 14 plasticity mechanisms , 210 SEP , 14 preparation , 211 single unit cortical neuron recordings , 15 SSEPs , 212 ulnar/peroneal nerve , 14 subcortical pathways , 212 unicellular/unit brain recording studies , 13 temporal lobe resections , 210 visual EPs , 11 tumor resection , 212 Brain mapping , 41 language sites , 212–213 motor sites , 213 preoperative assessment and surgical suitability , 210–211 C Cortical motor stimulation , 4 Cathode ray oscilloscope (CRO) , 12 , 14 Cortical stimulation mapping Cellular membranes , 49 anesthesia , 162 Central area (primary sensorimotor area) cognitive models , 141 central sulcus , 30 , 31 craniotomy , 141 cortical stimulation , 33 DCS , 141 dominant curves types , 31 equipment , 161 , 162 hand motor and sensory activation , 33 eloquent cortex , 63 motor defi cits , 31 fi ducial markers/anatomical landmarks , 141 postcentral gyrus , 31 functional imaging , 160–161 precentral gyrus , 31 generous craniotomy , 67 sensory and motor functions , 30 indications , 159 somatotopic sensory organization , 30 , 32 language cortex (see Language cortex, cortical tongue identifi cation , 30 stimulation mapping) tongue sensory region , 32 and MEPs , 70–71 Central nervous system (CNS) nTMS , 141 , 142 primary/basic somatic sensory information , 16 , 17 pathology , 159 reticular ascending arousal system , 17 patient , 161 Cerebral cortical motor mapping , 2 preparations and positioning , 162 Cerebral cortical stimulation studies , 4 rTMS , 141 Cerebral localization of function , 1 somatosensory cortex Cingulum bipolar stimulator , 69 bipolar disorders , 195 focal seizure , 69 cingulate cortex , 195 Ojemann cortical stimulator , 69 subgenual , 195 repetitive electrical stimulations , 69 , 70 tracer injection techniques , 195 serum anticonvulsant levels , 69 Index 223 SSM , 165 Direct electrical stimulation (DES) mapping , 10 stimulation pitfalls , 165 cortical region , 41 surgical endpoints , 165–168 (see also Transcranial subcortical region , 41 magnetic stimulation (TMS)) Discrete cortical threshold stimulation movements , 10 unipolar galvanic stimulation , 7 DTI. See Diffusion tensor imaging (DTI) Cortical stimulation studies , 10 Corticobulbar tract fi bers , 124 Corticospinal tract (CST) , 51 , 124 E Craniotomy ECoG. See Electrocorticography (ECoG) draping , 162 EEG. See Electroencephalography (EEG) electrocorticography , 163 Eigenvalues , 49 language mapping , 164 , 165 Eigenvectors , 49 lesion/seizure focus , 163 Electrical stimulations , 1 neuronavigation , 163 bipolar , 183 , 184 occipital focus , 163 cortical and subcortical , 184 sensorimortor stimulation , 163 , 164 cortex , 63 , 69 SSEP , 163 intraoperative mapping , 183 monopolar , 184 , 185 phonological paraphasias , 184 D Electrocorticography (ECoG) , 9 , 163 Data driven (model free) analysis , 45 anesthesia , 93 DCS. See Direct cortical stimulation (DCS) contralateral mastoid , 93 Dexamethasone , 214 EEG signal processing , 92 DICOM fi le formats , 53 frequency rhythms , 92 Diffusion anisotropy , 49 functional mapping , 91 Diffusion tensor imaging (DTI) , 49 , 107 chronic implants , 100 cadaver dissections , 196 cortical stimulation , 101 fi ber tract dissection , 182 , 183 EEG , 100 and fMRI , 52 epilepsy monitoring units , 101 frontal lesion and motor functions , 55–57 Foerster’s direct stimulation , 101 IFOF , 193 , 194 optical imaging , 101 inferior longitudinal fasciculus , 191 specifi city and sensitivity , 101 language cortex , 53–55 inter-electrode coherence and causality , language tracts , 51 96–98 limitations , 51–52 intraoperative technique , 91 middle longitudinal fasciculus , 191 neurophysiology and neuroanatomy , 98 motor tract , 50 , 51 phase-locking levels , 94 , 95 neoplasms , 42 postoperative memory defi cits and anomia , 91 optic radiations , 186 recording parameters , 93 plasticity , 197–199 standard evoked potential systems , 92 presurgical brain mapping , 52 , 53 stimulus parameters , 93 subcallosal/aslant fasciculus , 188–190 subdural electrodes , 92 tractography (see Tractography, DTI) white-matter pathways , 91 validity , 49–50 Electroencephalography (EEG) visual tract , 51 and clinical neurophysiology , 15 uncinate fasciculus , 192 cortical , 11 white matter tracts , 42 ECOG , 85 Diffusion tensor imaging fi ber tractography electrical current variations