The Approach External is identified by letter "X" and occupies the 5th position in the ICD10-PCS procedure code structure.
Below a selection of ICD 10 PCS codes related to 0NJ0X
Inspection of Skull, Percutaneous Approach
Inspection of Skull, External Approach
Inspection of Skull, Open Approach
Inspection of Skull, Percutaneous Endoscopic Approach