Stimulation and Recording parameters While studying dorsal column mapping in intramedullary spine tumor surgery.

Stimulation Parameters.

• Electrical stimulation is typically delivered using a handheld concentric bipolar stimulation probe that is designed to safely deliver controlled electrical pulses to the dorsal columns of the exposed spinal cord. [Note- Concentric probe usually prefers because its contain less diameter between two pole which is anode and cathode to complete the circuit means pass the current.]

• Intensity for excite the cell is usually set at low levels to avoid volume conduction and also causing damage to the neural tissue. The intensity is gradually increased until a sensory response is elicited. Our preferable intensity usually 0.3-0.6 milliampere in intact sensory pathways and also we increase the strength of stimulation incase of sensory affected patient, due to myelopathy.

Our setup 

• A single square pulse.

• Pulse duration 200-300 microsecond.

• Frequency of stimulation 2-4 Hz .

• Stimulating intensity 0.3-0.6 milliampere.

Recording Parameters

The location and characteristics of the sensory responses are used to map out the sensory pathways of the spinal cord and determine their relationship to the intramedullary tumor.

Montage for recording electrode .

Filter setting usually prefer as per machine standard or it can be modified according to IONM team.

Selection of stimulating and recording parameters during dorsal column mapping it can be vary on IONM team . The electrophysiology team and surgical team can accurately identify the sensory pathways of the spinal cord and safely navigate around them during intramedullary spine tumor surgery. This helps to preserve sensory function and optimize surgical outcomes for the patient.

• What are challenges can come during studying this technique.?

• Choice of anesthesia drugs?

• What are the relation between Fasciculus gracile and cuneate ?

Related this article.

Dorsal column Mapping in intramedullary spine tumor .

https://neurointraoperative.com/wp-admin/post.php?post=1777&action=edit

https://pubmed.ncbi.nlm.nih.gov/24448182

Question.

How much current to be used for dorsal column mapping?.

Inhalation drugs can hamper the signals?.

Why it is important ?.

If we don not use mapping what can happen?.