Intraoperative Spinal Cord Mapping by Direct cord Stimulation

Brief.

Lateral corticospinal tract/Ventral column mapping is another important technique being used during intramedullary spine tumor surgery to identify and preserve motor pathways within the spinal cord.

• Direct stimulation of the spinal cord with EMG recording the extent of the tumor margin at its interface with functional tracts.

• This is another modality especially in the ventral aspect of tumors, where tumor plane can be indistinguishable from neural tissue. Marginal stimulation/direct fiber stimulation mapping benefit of preemptively identifying critical fibers and allowing proactive adjust.

Here trying to show some images to understand in better way .

Figure 1

When started to stimulate the mid of tumor there was no response elicited at 2 milliampere .

Figure 2.

When started to stimulate the lateral of tumor there was response elicited at 1.2 milliampere right side.

This technique is useful in when tumor toward anterior and also when Motor Evoked Potential baseline is not reliable and also to differentiate between functional and nonfunctional tissue , {especially anatomy of cord distortion due tumor}, here will understand through cartoon image.

The results of stimulation mapping demonstrate the location of functional tracts in the close vicinity of tumor margins. A. Stimulation at 0.9 mA, triggered EMG response seen in left (L) thenar-hypothenar (TH, hand). B: Stimulation at 0.8 mA, triggered EMG response seen in left abductor hallucis (AH, foot flexors). C. Stimulation at 1.0 mA, triggered EMG response seen in right (R) thenar-hypothenar (TH, hand). D: Stimulation at 1.0 mA, triggered EMG response seen in right extensor hallucis longus (EHL-AE). AE = abductor hallucis and extensor hallucis longus; MG = medial gastrocnemius; TA = tibialis anterior.

Anterior corticospinal tract/Ventral column mapping of the spinal cord motor pathways by using direct stimulation may improve the safety of intramedullary tumor resection.

Related this article.

Stimulating and Recording Parameters of direct cord stimulation in intramedullary spine tumors.

https://neurointraoperative.com/wp-admin/post.php?post=1794&action=edit

https://www.researchgate.net/publication/268879347_High-resolution_direct_microstimulation_mapping_of_spinal_cord_motor_pathways_during_resection_of_an_intramedullary_tumor

Question.

Why it is important for marginal stimulation?

What exactly does this mapping?

Can we differentiate between functional and non functional tissue?.

What is the correlation between the D wave and mapping?.