ApplicationsProceduresNeurosurgerySubcortical motor mapping

Safe tumour resection with intraoperative mapping

During neurosurgical procedures in the motor cortex and motor pathways, precise work is of utmost importance. To avoid damaging functional structures during tumour resection or haemostasis, it is essential to know where these structures are located at all times. Continuous dynamic mapping offers an efficient and safe way to support surgeons.

Introduction to dynamic intraoperative mapping

Surgical technique

Preparation

Recording electrodes in the target muscles are required for motor mapping. During surgery on the left hemisphere, muscles on the right side of the body must be recorded and vice versa. In order to be able to recognise general changes and technical defects, it is highly recommended that some muscles on the opposite site are also recorded for comparison. In general, small muscles with more motor units are to be preferred. Covering various areas such as the head, upper and lower extremities ensures a more complete representation of the pathways.

A setup can contain, for example:

M. orbicularis oris
M. masseter
M. deltoideus
M. abductor pollicis brevis
M. tibialis anterior
M. abductor hallucis

The electrodes should be placed after the patients have been preoperatively informed and anaesthesia has been induced. Precise placement in the muscle and careful fixation, as well as the use of a bite block to prevent bite injuries, if necessary, must be observed. If other monitoring modalities, for example SEP, are planned, the corresponding electrodes should be placed at the same time.

Patient positioning and connection
After the patients have been placed in the surgical position, the person carrying out the monitoring connects the monitoring device to the electrodes. A technical functional test with impedance measurement, a tapping test to identify the muscles and a careful inspection of all connections are mandatory. Baseline measurements should be taken and documented before the start of surgical measures.

Mapping preparation
To prepare the mapping, the stimulation probe or Mapping Suction Probe used must be ready on the instrument table. A reference electrode is placed and fixed at the edge of the surgical field, for example in the subcutaneous tissue. This electrode and the connection cable of the probe or suction device are then connected to the appropriate channel of the monitoring system in the non-sterile area by the person responsible for monitoring.

The instruments used can now be tested by the surgeons making contact with the tissue near the reference electrode and the monitorists triggering the stimulation. A current flows, which is reported back by the monitoring device.

Procedure

If mapping is to be performed after opening the dura, the surgical team consults with the monitoring team to determine the stimulation intensity at which to begin. It has proven effective to first carry out a direct stimulation of the motor cortex at a low intensity to determine if everything is working properly from a technical point of view. Such stimulation should evoke responses in the respective muscles of the motor area at intensities of 1–10 mA. If this is the case, the entry point for the surgery is chosen and the intensity is set to the agreed level.

Illustration: mapping suction probe application

The tumour resection now begins, using the suction device with continuous dynamic mapping. The sound output of the monitoring device can be used to emit a safety tone to the surgical team in the event of a negative signal. As soon as the distance to the pyramidal tract decreases during the course of the tumour resection, a positive signal is registered in the muscles and emitted as a sound. The resection is then continued at a different location until a response is triggered here too, thus achieving the same distance from the pyramidal tract. If a response is triggered everywhere in the peripheral area of the resection cavity, the intensity is reduced by 1–2 mA, so that the signal becomes negative again. In this way, the surgeons slowly approaches the pathways.

During the procedure, the integrity of the entire motor pathways should be checked regularly by means of direct cortical stimulation, for example using a strip electrode placed on the motor cortex. If there is proximal damage, mapping cannot show a positive response and further damage may occur unnoticed.

At 5 mA, a break should be taken and a decision made on how to proceed. Depending on the type of tumour, the procedure discussed with the patients, the planned extent of resection and the tumour’s tendency to bleed, either the resection can be terminated and haemostasis started or the resection can be taken closer to the pyramidal tract. The latter is associated with a corresponding risk of at least temporary motor deficits. It should be noted that the correlation “1 mA corresponds to 1 mm” is no longer reliable for distances of less than 3 mm.

Product information

SDN electrodes 15/2000, stainless steel

533646

SDN electrodes 15/2000, stainless steel

1.5 mm touchproof connector DIN 42802, pair of electrodes red/black, red/white, blue/black, blue/white, yellow/black, yellow/white, violet/black, violet/white, grey/black, grey/white, needle length=15 mm, needle diameter=0.45 mm, cable length=2000 mm, disposable product, EO sterilised

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Corkscrew electrode set spiral needle 0.6 mm with tip cable 1.5 m

530751

Corkscrew electrode set spiral needle 0.6 mm with tip cable 1.5 m

With 1.5 mm touchproof male connector DIN 42802, 10 sterile sets with each 6 electrodes red, green, yellow, blue, black and white, each individually sterile packed, disposable product, EO sterilised

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Stimulation probe 130 mm monopolar, bayonet, ball tip

525615

Stimulation probe 130 mm monopolar, bayonet, ball tip

1.5 mm touchproof connector DIN 42802, bayonet, ball diameter=2.5 mm, working length=130 mm, total length with handle=245 mm, with neutral SDN electrode black, cable length=3000 mm, disposable product, EO sterilised

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Cortex Strip Electrode 4 contacts – 1 strip with cable

611014

Cortex Strip Electrode 4 contacts – 1 strip with cable

For cortical recording and stimulation, with connection cable, 4x1.5 mm touchproof connectors, cable length=1800 mm, contact material stainless steel, contact diameter=4.0 mm, contact distance=10 mm, disposable product, EO sterilised

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Mapping Suction Probe 3/90, monopolar

525650

Mapping Suction Probe 3/90, monopolar

Among others for continuous mapping by Raabe, work length=90 mm, total length=200 mm, Lumen: 9fg–3 mm, isolated, active tip=2 mm, connecting cable: red, neutral electrode: black, cable length=3000 mm, disposable product, EO sterilised

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Mapping Suction Probe 3/130, monopolar

525651

Mapping Suction Probe 3/130, monopolar

Among others for continuous mapping by Raabe, work length=130 mm, total length=230 mm, Lumen: 9fg–3 mm, isolated, active tip=2 mm, connecting cable: red, neutral electrode: black, cable length=3000 mm, disposable product, EO sterilised

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Mapping Suction Probe 2/90, monopolar

525655

Mapping Suction Probe 2/90, monopolar

Among others for continuous mapping by Raabe, work length=90 mm, total length=200 mm, Lumen: 6fg–2 mm, isolated, active tip=2 mm, connecting cable: red, neutral electrode: black, cable length=3000 mm, disposable product, EO sterilised

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Mapping Suction Probe 2/130, monopolar

525656

Mapping Suction Probe 2/130, monopolar

Among others for continuous mapping by Raabe, work length=130 mm, total length=230 mm, Lumen: 6fg–2 mm, isolated, active tip=2 mm, connecting cable: red, neutral electrode: black, cable length=3000 mm, disposable product, EO sterilised

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Application package Cortical for C2 Xplore

508545

Application package Cortical for C2 Xplore

Consisting of software license "Cortical", Body Box and license for 8-channel recording.

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C2 Xplore

508288

C2 Xplore

For intraoperative neuromonitoring. Easy-to-use 8-channel EMG monitor with 2 integrated stimulators, up to 6 application fields and digital integration in the operating theatre, maximum interconnection online and offline. Mains lead and foot switch included. Can be used in combination with an application package.

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ISIS Xpert plus 32-channel system for neurosurgery

504004-32CH

ISIS Xpert plus 32-channel system for neurosurgery

The powerful ISIS Xpert plus combines mobility with functionality. It consists of an equipment cart with panel PC, height-adjustable monitor, laser printer, keyboard drawer, two large accessory drawers, constant-current stimulator, amplifier with a total of 32 recording channels (56 inputs: 8 referential and 48 differential) and all necessary adaptor boxes.

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ISIS Xpert 32-channel system for neurosurgery

504005-32CH

ISIS Xpert 32-channel system for neurosurgery

The powerful ISIS Xpert combines mobility with functionality. It consists of an equipment cart with panel PC, keyboard drawer, accessory basket, constant-current stimulator, amplifier with a total of 32 recording channels (56 inputs: 8 referential and 48 differential) and all necessary adaptor boxes.

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ISIS Xpert 16-channel system

504005-16CH

ISIS Xpert 16-channel system

The powerful ISIS Xpert combines mobility with functionality. It consists of an equipment cart with panel PC, keyboard drawer, accessory basket, constant current stimulator, amplifier with a total of 16 recording channels (24 inputs: 8 referential and 16 differential) and all necessary adaptor boxes.

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ISIS Xpress 32-channel system for neurosurgery

504006-32CH

ISIS Xpress 32-channel system for neurosurgery

The ISIS Xpress is the portable version of the ISIS IOM system. It consists of the ISIS Xpress base unit, trolley, notebook, notebook and accessory bag, constant current stimulator, amplifier with a total of 32 recording channels (56 inputs: 8 referential and 48 differential) and all necessary adaptor boxes.

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ISIS Xpress 16-channel system

504006-16CH

ISIS Xpress 16-channel system

The ISIS Xpress is the portable version of the ISIS IOM system. It consists of the ISIS Xpress base unit, trolley, notebook, notebook and accessory bag, constant current stimulator, amplifier with a total of 16 recording channels (24 inputs: 8 referential and 16 differential) and all necessary adaptor boxes.

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