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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

This manuscript describes a method for continuous video EEG recordings using multiple depth electrodes in neonatal mice undergoing hypoxia-ischemia.

Abstract

Hypoxia ischemia is the most common cause of neonatal seizures. Animal models are crucial for understanding the mechanisms and physiology underlying neonatal seizures and hypoxia ischemia. This manuscript describes a method for continuous video electroencephalogram (EEG) monitoring in neonatal mice to detect seizures and analyze EEG background during hypoxia ischemia. Use of video and EEG in conjunction allows description of seizure semiology and confirmation of seizures. This method also allows analysis of power spectrograms and EEG background pattern trends over the experimental time period. In this hypoxia ischemia model, the method allows EEG recording prior to injury to obtain a normative baseline and during injury and recovery. Total monitoring time is limited by the inability to separate pups from the mother for longer than four hours. Although, we have used a model of hypoxic-ischemic seizures in this manuscript, this method for neonatal video EEG monitoring could be applied to diverse disease and seizure models in rodents.

Introduction

Hypoxic ischemic encephalopathy (HIE) is a condition that affects 1.5 in 1000 newborns annually and is the most common cause of neonatal seizures1,2. Infants who survive are at risk for various neurological disabilities such as cerebral palsy, intellectual disability, and epilepsy3,4,5.

Animal models play a critical role in understanding and investigating the pathophysiology of hypoxia ischemia and neonatal seizures6,7. A modified V....

Protocol

All animal studies were approved by the Institutional Animal Care and Use Committee (IACUC) of the University of Virginia.

1. Electrode building/cable building

  1. Use a unipolar insulated stainless-steel wire (0.005” bare diameter, 0.008” coated) to make an electrode that is connected with a female socket connector (female receptacle connector 0.079).
  2. Use a special custom-made cable to connect animals to the amplifier.
    1. Attach a male 4-pin connector (M.......

Representative Results

Seizure semiology

Neonatal hypoxia-ischemia exposure results in both generalized and focal seizures in mice (Figure 1A-C). Video EEG recordings allow electrographic findings to be correlated to behavior on video. These behaviors were scored using a previously published neonatal rodent behavioral seizure score (BSS)16. In addition to BSS, we categorized events based on whether the behavior was focal/unilateral, bila.......

Discussion

We have presented a model for continuous video-EEG monitoring in neonatal mice during hypoxic-ischemic seizures. Video analysis in conjunction with EEG allows characterization of seizure semiology. Analysis of EEG allows for extraction of power spectrograms and background amplitude analysis.

Correct and careful placement of electrodes is crucial in this protocol, as injury during electrode placement or inaccurate placement can significantly affect results. Assessment of normal baseline EEG act.......

Acknowledgements

We acknowledge the following funding sources: NIH NINDS – K08NS101122 (JB), R01NS040337 (JK), R01NS044370 (JK), University of Virginia School of Medicine (JB).

....

Materials

NameCompanyCatalog NumberComments
SURGERY
Ball Point ApplicatorMetrex Research8300-Fi-bond applicator
Cranioplast (Powder/Resin)ColteneH00383Perm Reline/Power
I-BondKulzer GmbH, Germany
LOOK Silk SutureSurgical Specialities CorporationSP115LOOK SP115 Black Braided Silk Non absorbable surgical suture
RS-5168 Botvin ForcepsRoboz Surgical InstrumentRS5168Forcep for surgery/ligation
RS-5138 Graefe ForcepsRoboz Surgical InstrumentRS5138Forcep for surgery/ligation
UV light for I-BondBlast Lite By First MediaBL778UV ligth for I-bond
Vannas Microdissecting ScissorRoboz Surgical InstrumentRS5618Scissor for ligation
Vet Bond3M Vetbond1469SBVet Glue
HYPOXIA
HypoxidialStarr Life Science
Oxygen sensorMedical ProductsMiniOxI- oxygen analyzer/sensor for hypoxia rig
EEG RECORDING
Female receptacle connector 0.079"Mill-Max Manufacturing Corp832-10-024-10-001000Ordered from Digikey
Grass AmplifierNatus Neurology IncorporatedGrass Product
LabChart ProADI InstrumentsSoftware to run the system
Male Socket Connector 0.079"Mill-Max Manufacturing Corp833-43-024-20-001000Ordered from Digikey
Operational AmplifierTexas Instruments, Dallas, TX, USATLC2274CDTLC2274 Quad Low‐Noise Rail‐to Rail Operational Amplifier
Operational AmplifierTexas Instruments, Dallas, TX, USATLC2272ACDRTLC2274 Quad Low‐Noise Rail‐to Rail Operational Amplifier
Stainless Steel wireA-M Systems7914000.005" Bare/0.008" Coated 100 ft
Ultra-Flexible WireMcMaster-Carr9564T136 Gauze wire of various color

References

  1. Vasudevan, C., Levene, M. Epidemiology and aetiology of neonatal seizures. Seminars in Fetal & Neonatal Medicine. , (2013).
  2. Volpe, J., et al. Neonatal Seizures. Volpe's Neurology of the Newborn. , 275-321 (2018).
  3. Shankaran, S., et al.

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