Awake Craniotomy: Role in Neurosurgical Management

Christine StewartUniversity of Minnesota, MS4

Outline

• Case R.P.• Classic indications and exclusion criteria• Factors to consider when defining eloquent

areas• Recommendations

R.P.• 42 RHM w/ long history of seizures recently changed in character, worsening

H/A over past several months. Wife notes increasing apathy, slow processing• Difficulty with word-finding, long-term memory, mood-swings• Other PMHx:

– Cyclist v. car 1983: LOC 1-2 minutes, right frontal frx w/ CSF leak meningitis– 1st seizure 1985 GTC w/ auras– Another episode of meningitis 1985 intracranial abscess R. frontal lobe R.

frontal craniotomy– Imaging from 2002-2008 show a hypodensity in the left frontal lobe which was

interpreted as encephalomalcia given hx– Hypothyroidism

• Medications:– Lamictal 400 mg– Vimpat 200 mg BID– Levothyroxine

Imaging

Classic Indications for Awake Craniotomy1

• Surgery in ‘eloquent’ brain– Near motor strip – Speech/language centers– Thalamus

• Removal of brainstem tumors• Search for a focus of seizure activity

Exclusion Criteria2,3, 4

• Inability to cooperate: dysphasia, language barrier, emotional labiality, cognitive impairment

• Low occipital tumors • Tumors with significant dural attachment• Patients < 11 years old5

Eloquent areas and factors to consider: Anatomical variability6

– ICBM 452 atlas• “Average” brain

– Factors: sex, age, handedness, neurological and psychiatric disease

Eloquent areas and factors to consider: Functional variability6,7,8

– Even areas with the same anatomical landmarks may not harbor the same underlying function• Motor cortex variability:

– “Hand knob” of pre-central gyrus can represent primary motor cortex or premotor cortex

– Stimulation in pre-central cortex can result in sensory and motor responses or motor responses in > 1 motor group

– Primary motor area may extend > 20 mm anterior to the central sulcus

Eloquent areas and factors to consider: Functional variability

• Variability in language cortices6

– > 4cm of variability in intraoperative speech arrest

J Neurosurg 71:316–326, 1989.

Eloquent areas and factors to consider: Effect of space-occupying lesions

– Unusual functional acquisition: congenital lesions (AVMs) higher incidence right v. left sided language6

– Reorganization: LGG (low grade gliomas)/other adult neurological injury reorganization of speech center s.t more frontal speech centers in pt vs. controls10

– Extent likely depends on time-course of injury9

– Illustratively, these patients rarely present with neurodeficits9

Variability in Mapping Functional Localization2,6

• Either measuring electrophysiological signals or perfusion

• Electrocortical stimulation mapping (ESM) identifies essential and involved areas– Other methods seem to be more sensitive to map all

involved areas, but do not identify which are essential

• If essential area is identified:– Appropriate resection margins have not been

recommended

Effects of Mapping4

% of all patients % w/ post-op neurodeficits

% w/ deficits who were previously intact

+ Mapping 22.5% 20.9% 4.4%

- Mapping 77.5% 13.5% 1.8%

When considering awake craniotomy:

• Outcomes– No prospective randomized control trial has been done directly comparing awake v. GA3

• Patient experience– Awake procedures are well-tolerated11

• Overall satisfaction rated: 71-93%• Significant pain identified: 8-29%• All of this literature asks post-op and relies on recall

– Non-language deficits are noted after surgeries done under GA2

• Visual, spatial perceptions, cognitive and behavioral disorders noted as more individuals do neuropsychological testing.

• Cost4

– Reduces operating time• Dependent on experience level

– Reduces post-op ICU stay– Reduces total hospital stay

• Median LOS: 1 day

Recommendations

• No ‘gold standards’ for pre-operative mapping b/c no outcomes-correlated evidence– fMRI at minimum – DTI may help define white matter tracts in and

around the lesion– Others: MEG, PET

• Intra-operative monitoring should be mandatory– only technique with validated outcomes measures

References1 Greenberg, M. Handbook of Neurosurgery. 7th edition. 2 Duffau, H. Awake surgery for non-language mapping. Neurosurgery. 66:523-529, 2010.3 Kirsch, B. and Bernstein, M. Ethical challenges with awake craniotomy for tumor. Can. J. Neurol Sci 39: 78-82, 2012.4 Serletis, D. and Bernstein, M. Prospective study of awake craniotomy used routinely and non-selectively for supratentorial tumors. J Neurosurgery. 107:1-6, 2007.5 Berger, MS. The impact of technical adjuncts in surgical management of cerebral low grade gliomas of childhood. J. of neuro-oncology. 1996; 28:129-155.6 Pourtrain, N. and Bookheimer, S. Reliability of anatomy as a predictor of eloquence: a review. Neurosurg Focus 28:E3, 2010.7 Shinoura N, Suzuki Y, Yamada R, Tabei Y, Saito K, Yagi K:Precentral knob corresponds to the primary motor and premotor area. Can J Neurol Sci 36:227–233, 20098 Uematsu S, Lesser R, Fisher RS, et al: Motor and sensory cortex in humans: topography studied with chronic subdural stimulation. Neurosurgery 31:59–72, 19929 Desmurget M, Bonnetblanc F, Duffau H: Contrasting acute and slow-growing lesions: a new door to brain plasticity. Brain 130:898–914, 200710 Lucas TH II, Drane DL, Dodrill CB, Ojemann GA: Language reorganization in aphasics: an electrical stimulation mapping investigation. Neurosurgery 63:487–497, 200811 Manchella, S. et al. The experience of patients undergoing awake craniotomy for excision of intracranial masses: expectations, recall, satisfaction and functional outcome. British Journal of Neurosurgery. June 2011. 25(3): 391-400.