Neurosurgery Coding Alert

Know how clinical indications lead to proper code choice.

When a patient suffers from a subdural hematoma or other form of brain compression, burr hole surgery is often the go-to procedure. Burr hole craniostomy occupies a distinct niche in neurosurgery: more precise and invasive than a simple twist drill craniostomy, yet significantly less extensive than a full craniotomy.

During these procedures, surgeons create one or more small, circular openings in the skull to access the subdural space, ventricles, or intraparenchymal areas. This allows for the evacuation of blood, fluid, or pus and provides rapid relief from life-threatening intracranial pressure.

For medical coders, viewing burr holes as “small openings with big impact” underscores why operative documentation must clearly specify the approach, exact target site, and therapeutic intent — details that directly guide selection from the twist drill, burr hole, and trephine code family. This is an important distinction as surgical technique matters when it comes to code choice.

Read on for more information on coding burr hole surgeries.

Visualize ‘Stacked’ Cranial Layers to Spot Burr Hole Surgery

The CPT^® Twist Drill, Burr Hole(s), or Trephine code set starts with 61105 (Twist drill hole for subdural or ventricular puncture) and ends with 61253 (Burr hole(s) or trephine, infratentorial, unilateral or bilateral). Most of the codes in this set are for burr hole procedures, but coders should know when surgeons are likely to use each technique.

Clinically, burr holes are a common intervention for subdural hematomas, particularly chronic or acute-on-chronic collections that lead to gradual neurologic deterioration in vulnerable patients, such as the elderly or those on anticoagulation therapy. The choice of burr hole over watchful waiting, twist drill aspiration, or proceeding to craniotomy hinges on key factors: the hematoma’s location and characteristics, underlying brain anatomy, the patient’s comorbidities, and surgical risk.

When coders grasp how these clinical drivers influence procedure selection, they can more confidently dissect operative reports, differentiate nuances in documentation, and assign the most accurate code — avoiding common pitfalls like under- or overcoding the extent of access or purpose.

From a coding perspective, visualizing the cranial layers as an organized stack — from superficial to deep — sharpens interpretation of operative reports. Burr hole procedures traverse these outer layers in a controlled manner, targeting the subdural space or, in some cases, the ventricular system deeper within the brain, without the large bone flap required in craniotomy.

Identify Specifics of Burr Hole Surgeries

To help coders map documentation to codes, here are the eight standard steps in a burr hole craniostomy:

1. Preoperative preparation and positioning: The patient is positioned supine (or lateral for specific access), with the head secured. The surgeon reviews imaging (CT/MRI) to confirm hematoma location and plan burr hole site(s) — often frontal, parietal, or temporal over the convexity. Scalp hair is shaved/clipped in the target area, and the site is marked.
2. Anesthesia and sterile prep: General anesthesia is administered (local with sedation possible in select cases). The scalp is cleansed with antiseptic solution, draped sterilely, and local anesthetic with epinephrine is infiltrated for hemostasis. 
3. Incision and exposure: The surgeon makes a small linear incision (typically 2-4 cm) over the planned site. The surgeon dissects through scalp layers (skin, subcutaneous tissue, galea) and retracts to expose the pericranium/periosteum, which they incise and elevate.
4. Burr hole creation: Using a perforator drill or cranial perforator, the surgeon drills one or more small circular openings (usually 12-14 mm in diameter) through the skull bone until the dura is visualized. Bone edges are waxed for hemostasis, and any bone fragments are removed.
5. Dural opening and access: The surgeon opens the dura (often in a cruciate or linear fashion) to expose the subdural space or deeper targets like ventricles if indicated. This step is critical — documentation of dural opening confirms true burr hole access versus twist drill without dural breach. 
6. Evacuation and irrigation: The hematoma/fluid is evacuated using gentle suction, irrigation with saline (or artificial cerebrospinal fluid), and sometimes blunt dissection or lavage to remove clots. Membranes may be fenestrated if chronic.
7. Drain placement (if performed): A subdural or ventricular drain/catheter is often inserted for postoperative drainage and connected to a collection system — operative notes frequently detail this for codes involving catheter placement (for example, 61107 [Twist drill hole(s) for subdural, intracerebral, or ventricular puncture; for implanting ventricular catheter, pressure recording device, or other intracerebral monitoring device] or 61210 [Burr hole(s); for implanting ventricular catheter, reservoir, EEG electrode(s), pressure recording device, or other cerebral monitoring device (separate procedure)]). 
8. Closure: The surgeon closes the dura (or leaves it open in some cases), inspects bone edges, and closes the scalp in layers with sutures or staples. Hemostasis is ensured throughout.

These steps highlight why operative reports must explicitly describe the depth of access (for example, “dura opened,” “subdural space entered”), number of holes, location (for example, “bifrontal burr holes”), and adjuncts like drain insertion — details that differentiate codes within the 61105-61253 family and prevent under- or overcoding.

Check out Subdural Hematoma Specifics

Subdural hematomas — particularly chronic or acute-on-chronic collections from slow venous bleeding — frequently drive the decision for these procedures. These accumulations between the dura and arachnoid cause mass effect and rising intracranial pressure, manifesting as progressive headache, confusion, gait issues, or focal weakness over days to weeks. When the hematoma is thick, liquefied, and causing significant neurologic decline, burr holes (or twist drill variants) offer effective evacuation and pressure relief with reduced morbidity compared to craniotomy.

CT imaging is pivotal in guiding this choice, with reports detailing hematoma thickness, midline shift, and density (indicating chronicity and liquidity) to assess safe drainage through small openings. Remember, CT interpretation is billed by radiology unless the neurosurgeon separately documents and reports it.

Patient factors — such as advanced age, frailty, comorbidities, and anticoagulant/antiplatelet therapy — often tip the balance toward minimally invasive access when a patient suffers from a subdural hematoma.

Know Purpose of Surgery to Aid Code Choice

The 61105-61253 range encompasses twist drill, burr hole(s), and trephine procedures on the skull, meninges, and brain. These codes cover minimally invasive cranial access for diagnostic or therapeutic purposes, such as puncture, aspiration, evacuation, biopsy, catheter placement, or device implantation — without the extensive bone flap of craniotomy/craniectomy.

A key conceptual distinction lies in access extent: Twist drill techniques involve the smallest openings (hand-operated perforator for simple puncture or fluid withdrawal), often bedside or emergent. Burr hole(s) or trephine procedures create larger, controlled circular openings (typically 12-14 mm) using powered drills, enabling more thorough evacuation, irrigation, or adjuncts like drain insertion. This procedure is more suited for operating room settings and often has greater therapeutic impact.

Operative report phrasing directly guides code selection within this family. Watch for these common descriptions:

• “Burr hole(s) with evacuation and irrigation of subdural hematoma”: Signals targeted subdural access, drainage, and lavage (aligning with codes like 61154 [Burr hole(s) with evacuation and/or drainage of hematoma, extradural or subdural] for hematoma evacuation via burr hole)
• “Burr hole with drainage and catheter placement”: Indicates burr hole creation plus intentional catheter/drain insertion for ongoing subdural or ventricular management (pointing to codes specifying catheter placement or ventriculostomy)

By decoding these anatomic and procedural details, coders can confidently navigate the code range, differentiate minimal from more extensive access, and assign the most accurate code supported by documentation.

Include These Documentation Essentials for Burr Hole Coding

Accurate coding in the 61105-61253 family hinges on operative reports that explicitly capture the following must-have elements:

• Confirmed diagnosis (for example, chronic subdural hematoma),
• Laterality (right, left, or bilateral),
• Precise location (for example, frontal, parietal, or temporal convexity), and
• Target space (subdural, ventricular, or intracerebral).  

Surgeons must clearly describe the technique — specifying burr hole versus twist drill versus trephine — along with the number of holes created and whether a drain or catheter was placed for ongoing evacuation or drainage.

Additionally, references to preoperative imaging (for example, a CT showing hematoma thickness, midline shift, or density indicating chronicity) and the clinical indication — tying the pathology’s mass effect, neurologic decline, or patient risk factors to the chosen minimally invasive approach — provide critical support for medical necessity, help differentiate codes, and prevent denials or undercoding by ensuring the documentation fully justifies the selected code.

Alicia Scott, CPC, CPC-I, CRC, QPIN, Subject Matter Expert,
CCO.us (Certification Coaching Organization); Documentation Specialist, University of Missouri