The Western HQ is one of five other regional HQs created under the Army Ground Forces' (IRIA) 'Samen restructuring plan'. Operating on the assumption that they would face a simultaneous, multi-front attack that would preclude centralized strategic control of battles, the IRIA created these HQs to control operations and coordinate tactical actions within their respective theaters. By coordinating tactical actions at this level, the IRIA hopes to achieve their operational objective of regional integrity, which when taken as a whole comprises the national-level defense-in-depth strategy.
Their role is further described by the commander of the IRIA – BG Ahmed Reza Pourdastan – in a 2013 interview:
“With the objective that units be completely self-sufficient and be able to confront threats independently, we created five regional headquarters in the northeast, southeast, southwest, west, and northwest, and we designed the structure and organization of these headquarters to be self-sufficient and not need outside equipment when confronting threats. These HQs have all of the structure and organization required for an independent and self-sufficient unit, [including] support, and transport units, as well as hospitals.”[1/2]HQ Staff:
As of April 2014, the HQ's commander is Brig. Gen. 2nd-Class (BG2) Manoucher Kazemi.  It's deputy commander is BG2 Saeed Arablu.
Prior to the Samen Alaeme plan, the NEZAJA's western region was reported to include the Kermanshah and Ilam provinces, but has since been expanded to cover Kurdistan and part of the Hamedan province, and is primarily composed of the remnants of the 81st Armored Division, and a handful of other brigades. 
|Dashed red lines indicate uncertainty regarding chain of command and/or current-status.|
Although the HQ is reported to cover Kurdistan, the primary NEZAJA units based in Kurdistan - the remnants of the 28th Infantry Division - are described by other sources as subordinate to the NW HQ.  This is far from the only inconsistency in reporting on this region. In 09/2010, ISNA reported that the HQ would include the 81st Armored Division, 35th Commando Brigade, 71st Mechanized Infantry Brigade, 1st Army Aviation Combat Base, 404th Communications Group, 1st Region Support[& Logistics], and the Khatam ol-Anbiya Air Defense HQ. 
Then, in 03/2013, Mehr News reported a slightly modified order of battle that included the 81st Armored Division, 71st Air Defense Brigade, Army Aviation, 316th Brigade, 281st Brigade, 35th Commando Brigade, and 404th Communication Group.
Some of these inconsistencies can be easily explained - the addition of the 281st Brigade is due to the ongoing process of making divisional brigades independent, a process which had yet to affect the 81st Division in 2010. Presumably this process is still underway, explaining the lack of references to a hypothetical tactical/operational coordinating division HQ, or a 381st Brigade.
No 71st Air Defense Brigade (as per the 2013 ORBAT) has been previously identified, and may have been confused with the 71st Mechanized Brigade (as per the 2010 ORBAT). Even if this is the case, it has also been reported that this brigade is affiliated with 28th Division HQ and the NW HQ.
The suggestion that the locally-based contingent of the Khatam-ol Anbiya Air Defense Force would be subordinate to a NEZAJA command is notable since this force constitutes a separate branch of the Armed Forces, and would be akin to subordinating Navy or Air Force personnel to the Army Ground Forces.
Appendix - Staff IMINT:
[1/2] Rapid Reaction, the Focus of Future Wars: Evaluation of NEZAJA rapid reaction Forces from the Sacred Defense to the Samen Plan. AJA. 02/25/2013
 Commander of the Army's Western Region Headquarters: We are Ready to Defend the Revolution and the System. 04/17/14. IRNA.
 The Iranian Army is a Symbol of the Country's Power. 04/12/14. Fars News.
 Addition of Kurdistan and Parts of Hamedan to the Western Region HQ. 04/11/13. Fars News.
 North West Regional Operations HQ. 04/11/14. The Arkenstone.
 Commander of the Army's Western Operations Region HQ:
 [title] 09/13/2010. ISNA.
 The Country's Skies are Watched by Army Air-Defense Units / Army Lodging Ready. 04/11/13. Mehr News.