What do you use for the letter typically from your home chairman if you don't have one? We have neither a residency nor a neurosurgery chairman/faculty member affiliated with our school. Closest I can get from my school M4 neurosurgery rotation is a non-academic neurosurgeon who is not technically faculty our school, just an affiliated hospital.
If you have a home program, you need a chair letter. IDK what to do when you don't have one. You also need chair letters from each away. On my aways, the coordinator pre-arranged meetings with the chairs so that we could ask for letters. It is totally expected on their end. Missing a chair letter would be a red flag IMO.
Get one from each away (Chair>PD>Other Faculty). You will also have your Dean's. In the absence of home NSG, get one from a home surgical related chair.
Guess I could have my dean of surgery as the 4th but I’ll never have worked with him or even rotated at his hospital in any capacity.
While ideally you would want them all to be from neurosurgeons or surgeon in the absence of it, i have talked to a few program directors enough to believe that letter contents gets heavy weight in making program rank lists. Several times it may also influence interview invites. With that in mind a good letter from a non-reknown neurosurgeon that knows you well and can speak in detail of your work ethic and character will get way more weight and attention than a letter from a well-known neurosurgeon that just says 'student rotated here'
The same goes for all your letters. It be slightly better to get a good letter from someone that knows you well, surgeon or not, may be more beneficial to you than getting a letter from a chair that doesn't know you. The caveat is that you do one to have letters from surgeons and at least 2 from neurosurgeons, but you can get this from your aways. A strategic thing you may consider doing is rotate on programs known to write meaningful letters. Dr. Murazko in Michigan, chair at UNC chapel hill are places I have heard from multiple sources that are good at writing meaningful letters. Consider asking other program directors what other chairs or pds from the last or last two application cycles have sent good letters.
Just my two cents
Sorry for all typos. Typing from phone with crappy autocorrect