FAQ for Neurology

Ambu® Neuroline Single Patient Surface Electrodes.

Which should I choose?

A solid gel electrode or an electrode with wet gel?

The many different examinations within clinical neurophysiology each have their special requirements for electrode characteristics. Therefore, the choice of electrode type must be based on the actual recording conditions.

Solid gel electrodes are made of soft and flexible materials, which make them suitable for examinations of children as well as for use on the face near the eyes or ears. Furthermore, the electrodes are repositionable making them very cost-effective in cases, where registrations are made from different sites on the same patient, for instance in Nerve Conduction Studies. The adhesive strength of a solid gel is not as strong as that of the adhesive used on a wet gel electrode. This is, however, partly compensated by the fact that the electrode adheres across the entire surface and not just around the sensor. When using solid gel electrodes it is important to prepare the skin carefully before positioning the electrode.

Wet gel electrodes achieve a faster electrical contact due to the rapid "wetting" of the skin. The electrode will also stick more firmly to the patient because of the acrylic adhesive around the sensor, making this type of electrode suitable for long-term examinations. These electrodes cannot however be repositioned.

Why are there so many different types of electrodes in the Neurology programme?

It can seem confusing with the many different electrode types and variants in the Neuroline programme. However, when making the product programme, we have tried to consider the requests from the market.The many different neurological examinations require different electrode properties. For instance:

• How long should they adhere to the patient?
• Should they be able to adhere to difficult sites of the body?
• Should they be repositionable?
• Should the lead wire be connected directly to the equipment or is a patient cable being used?

Furthermore, some customers prefer wet gel, while others prefer to work with solid gel.

Why are lead wires with unprotected pins no longer in the programme?

There have been some accidents caused by unprotected pins being connected to current-carrying contacts. In order to prevent such accidents in the future the FDA in the US has banned lead wires with plugs of unprotected metal. To comply with these new regulations for plugs we have excluded all electrodes with unprotected pins from our programme, which now only consists of safety connectors.

How many times can solid gel electrodes be repositioned?

Several factors determine this, such as skin preparation, type of skin and atmospheric humidity. Experience shows that under optimal conditions the electrodes can be repositioned 3 to 5 times. It must be pointed out that in order to avoid cross contamination the electrodes can only be repositioned on the same patient. The adhesive strength is at its maximum with the first placement of the electrode and will then gradually decrease according to the number of times it is repositioned. This is the case even with careful skin preparation.

EMG Needle Electrodes

Is there any difference in the recording quality between concentric and monopolar needles?

Yes, there is a difference in the recording characteristics between a concentric and a monopolar needle.

In the concentric design the electrode wire is located inside the lumen of the cannula and thereby shielded, giving a more stable baseline. The cannula shields the wire from picking up potentials from fibres located behind the tip. The sensitivity of the concentric EMG needle is therefore largest in the hemisphere facing the oblique elliptical surface.

Due to the asymmetric sensitivity function, the wave shape of the recorded potentials will vary if the electrode is rotated about its axis.

This problem is not observed with the asymmetric monopolar EMG needle. However, this electrode has a more unstable baseline (noise) due to the unshielded lead wire and the remote location of the reference electrode. It is thus more likely to pick up potentials from remote motor units.

Ambu® Neuroline Concentric

Can Neuroline Concentric be resterilised and re-used?

 No, disposable needles should never be re-used for another examination. When using invasive products the risk of blood transferred infections and viruses from one patient to another is considerably greater than with products which adhere to the skin. Serious and in some cases incurable diseases can be transmitted in this way, and this is a risk which must be taken very seriously. Therefore, it is essential to ensure that the needles are only used on one patient, and are discarded immediately afterwards.

Why is the 30 Gauge needle only available in 25 mm length?

 This is solely due to the mechanical strength of the needle. If the thin needle were longer it would flex and bend to a degree, which would make it impossible for the neurologist to fully control the positioning of the electrode.

Do Ambu Neuroline Concentric and Ambu Neuroline Monopolar fit other cables?

Apart from the Neuroline cable, our concentric needles fit cables from Nicolet and Meditec. They do not fit cables from Oxford Instruments (TECA/Medelec) or Medtronic (Dantec). Our monopolar needles will only accept our own cable. Does the Ambu Neuroline cables fit all monitors? The Neuroline cable has a 5-pole DIN-connector that fits all modern monitors. Some older equipment might require a special cable.

Ambu® Neuroline Monopolar

Can neurologists use another brand as a surface reference electrode?

Yes, they can use another brand of reference electrode. But for the best result, we recommend Ambu Neuroline 710 with 10 cm. lead wire as the reference electrode.

Are the reference electrodes and the monopolar needles separately connected to the machine with the touch-proof connector and plugging into the machine?

 Yes, the monopolar needle and the reference electrode are separately connected to the machine with a touch-proof safety connector (J or K connector for the surface electrode and DIN 42 802 for the monopolar needle).

Why are the cables only 76 cm (30”) long?

Because the cable for the monopolar needles is unshielded, it functions as an antenna - the longer the cable, the more noise.