A study of electrical impedance of oedematous cerebral tissue during operations

Go, K.G.; Veen, Pieternella H van der; Ebels, E. J.; Woudenberg, Fred

doi:10.1007/bf01401876

Cited by 18 publications

(3 citation statements)

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“…These values represent 46 and 33 % of total tissue water content which is consistent with morphological and physiological evidence of a greatly enlarged extracellular space 11,16 It is of interest to note that the calculated calcium content of oedema fluid was almost five times higher than the calcium activity of extracellular fluid, as determined with ion sensitive electrodes 13,25 In view of the multiple biological actions of calcium even a minor change of ionized calcium induced by the accumulation of oedema fluid could have considerable pathophysiological consequences. In the intact brain calcium is almost exclusively located in the extracellular compartment because powerful ion exchange mechanisms maintain an intra-/extracellular gradient of more than 1:10 40).…”

Section: Discussionsupporting

confidence: 86%

Experimental transplantation gliomas in the adult cat brain

et al. 1989

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In adult cats experimental brain tumours were produced by stereotactical xenotransplantation of the rat glioma clone F 98 into the internal capsule of the left hemisphere. Two to four weeks after transplantation tumours and peritumoural oedema were investigated by magnetic resonance imaging (MRI), electrophysiological recording and analysis of tissue content of water, electrolytes and extravasated serum proteins. Spherical tumours with a diameter of about 10 mm developed at the injection site and were surrounded by massive white matter oedema. Water content in peritumoural white matter increased from 2.63 +/- 0.17 to 3.65 +/- 0.19 ml/g d.w. (means +/- SD), sodium from 187 +/- 11 to 351 +/- 55 mueq/g d.w. and calcium from 7.4 +/- 1.1 to 13.3 +/- 1.3 +/- 1.3 mueq/g d.w. Potassium and magnesium did not change. Oedema development was associated with the extravasation of 18.0 +/- 16.8 mg/g d.w. albumin and 15.8 +/- 12.2 mg/g d.w. immunoglobulin. The calculated electrolyte content of oedema fluid approximated that of plasma but the serum protein content was about 40% lower. The ratio of low (albumin) to high (immunoglobulin) molecular weight proteins was the same in blood and oedema fluid. It is, therefore, concluded that peritumoural oedema consist of two components, a whole plasma extravasate and a protein-free ultrafiltrate. Peritumoural oedema could be clearly detected by MRI but differentiation between tumour and oedema was only possible after contrast enhancement with gadolinium-DTPA. The ratios of the intensities of the MR signal correlated linearly with the water content within white matter. MRI, in consequence, allows quantification of oedema provided a reference area with normal water content is present.

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Section: Discussionsupporting

confidence: 86%

Experimental transplantation gliomas in the adult cat brain

et al. 1989

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“…For Subject 2 the corresponding values were , , and and thus also within the expected range. Conductivities of CSF, skin, and bone were considered isotropic and assigned corresponding in vivo estimates of 1.654 S/m, 0.465 S/m and 0.010 S/m [ 26 , 44 – 47 ].…”

Section: Methodsmentioning

confidence: 99%

Enhancing Predicted Efficacy of Tumor Treating Fields Therapy of Glioblastoma Using Targeted Surgical Craniectomy: A Computer Modeling Study

et al. 2016

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ObjectiveThe present work proposes a new clinical approach to TTFields therapy of glioblastoma. The approach combines targeted surgical skull removal (craniectomy) with TTFields therapy to enhance the induced electrical field in the underlying tumor tissue. Using computer simulations, we explore the potential of the intervention to improve the clinical efficacy of TTFields therapy of brain cancer.MethodsWe used finite element analysis to calculate the electrical field distribution in realistic head models based on MRI data from two patients: One with left cortical/subcortical glioblastoma and one with deeply seated right thalamic anaplastic astrocytoma. Field strength was assessed in the tumor regions before and after virtual removal of bone areas of varying shape and size (10 to 100 mm) immediately above the tumor. Field strength was evaluated before and after tumor resection to assess realistic clinical scenarios.ResultsFor the superficial tumor, removal of a standard craniotomy bone flap increased the electrical field strength by 60–70% in the tumor. The percentage of tissue in expected growth arrest or regression was increased from negligible values to 30–50%. The observed effects were highly focal and targeted at the regions of pathology underlying the craniectomy. No significant changes were observed in surrounding healthy tissues. Median field strengths in tumor tissue increased with increasing craniectomy diameter up to 50–70 mm. Multiple smaller burr holes were more efficient than single craniectomies of equivalent area. Craniectomy caused no significant field enhancement in the deeply seated tumor, but rather a focal enhancement in the brain tissue underlying the skull defect.ConclusionsOur results provide theoretical evidence that small and clinically feasible craniectomies may provide significant enhancement of TTFields intensity in cerebral hemispheric tumors without severely compromising brain protection or causing unacceptable heating in healthy tissues. A clinical trial is being planned to validate safety and efficacy.

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“…Previous investigators have suggested that cerebral impedance measurements change with water content of the brain (Van Harreveld et a/. 1961a/. , Go et a/.…”

Section: Introductionmentioning

confidence: 99%

Transcephalic Impedance Measurement During Infancy

Reigel

Dallman

Scarff³

et al. 1977

Develop Med Child Neuro

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SUMMARY Transcephalic impedance is the measurement of resistance of the head to the flow of alternating current. Impedance determinations have been made in 35 normal infants from birth to one year of age. These infants, when serially studied, display a typical linear increase of impedance in the first year of life. At birth, impedance values range from 32 to 36ohms (Ω) and at one year from 75 to 85 Ω. Beginning at birth, serial determinations of transcephalic impedance on 56 children with angiographically‐confirmed hydrocephalus demonstrated a progressive decline in their impedance to values of 24 to 32ohms (Ω). After cerebrospinal fluid shunts had been inserted, impedance values returned to normal and followed a linear progression. In four children with myelomeningocele who did not develop hydrocephalus, serial impedance determinations during the first year were similar to values obtained in normal newborn infants. In shunt failure, impedance values fell increasingly below anticipated values. These observations often preceded accepted clinical indications of shunt malfunction. After shunt revision, impedance values rapidly returned to normal and followed the curve described for normal children. Abnormally low transcephalic impedance measurements were observed in other conditions such as Dandy‐Walker cysts, subdural effusions and hematomas, extra‐axial cysts and hydranencephaly. However, in 19 children referred for enlarging heads, the impedance values were within or above normal range and a diagnosis of macrocephaly was made. Transcephalic impedance measurement is a simple, rapid, inexpensive, non‐invasive aid in the evaluation of children with large heads. The method has proved reliable in screening well infants with macrocephaly and has assisted in the evaluation and treatment of hydrocephalus and shunt failure during infancy. RÉSUMÉ Mesure de 'impedance transencephalique durant la premiere enfance. 'inpŕdance transencŕphalique est la mesure de la rŕsistance de la tête au passage d̂un courant alternatif. La dŕtermination de 'impŕdance ŕtŕ faite chez 35 nourrissons normaux depuis la naissance jusqu'à 'âge d̂un an. Ces nourrissons ŕtudiŕs sŕrialement prŕsentent un accroissement linŕaire typique de 'impŕdance durant la premièe annŕe de la vie. A la naissance, les valeurs d̂impŕdance varient autour de 32–36 Ω et à un an autour de 75–85Ω. Une dŕtermination sŕriale de 'impŕdance transencŕphalique depuis la naissance chez 56 enfants prŕsentant une hydrocŕphalie confirmŕe par angiographie a montrŕ une diminution progressive de 'impŕdance jusqu'à des valeurs de 24–32Ω. Après shunt du liquide cŕphalorachidien, les valeurs d̂impŕdance retournent à la normale et suivent une progression linŕaire. Chez quatre enfants avec myŕlomŕningocèle qui ne prŕsentèrent pas d̂hydrocŕphalie, les dŕterminations sŕriales d̂impŕdance durant la première annŕe ŕtaient semblables aux valeurs obtenues chez les nouveaux‐nŕs normaux. En cas de faillite du shunt, les valeurs d̂impŕdance tombent en‐dessous du niveau attendu; ce fait prŕcède souven...

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A study of electrical impedance of oedematous cerebral tissue during operations

Cited by 18 publications

References 18 publications

Experimental transplantation gliomas in the adult cat brain

Experimental transplantation gliomas in the adult cat brain

Enhancing Predicted Efficacy of Tumor Treating Fields Therapy of Glioblastoma Using Targeted Surgical Craniectomy: A Computer Modeling Study

Transcephalic Impedance Measurement During Infancy

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