What are the benefits of starting the first burr hole in the side with a thicker hematoma during a bilateral burr hole craniostomy for bilateral chronic subdural hematoma?

Surgical Approach to Bilateral Chronic Subdural Hematoma: Starting with the Thicker Side

When performing bilateral burr hole craniostomy for bilateral chronic subdural hematoma, starting with the thicker hematoma provides critical advantages in preventing acute intracranial hypertension and herniation by addressing the side with greater mass effect first.

Primary Rationale: Mass Effect and Herniation Prevention

The fundamental benefit of evacuating the thicker hematoma first relates to immediate reduction of the most significant mass effect and intracranial pressure. This approach follows established neurosurgical principles for bilateral pathology where staged intervention minimizes catastrophic complications 1.

Intracranial Pressure Dynamics

• Draining the thicker hematoma first provides the greatest immediate reduction in intracranial pressure, which is critical when both sides contribute to elevated ICP 1
• The side with greater hematoma thickness typically exerts more midline shift and compression of vital structures, making its evacuation the priority 2
• Starting with the side of maximal mass effect prevents acute decompensation that could occur if the smaller hematoma is evacuated first, potentially causing rapid pressure shifts 1

Prevention of Contralateral Herniation

A critical but often overlooked risk is acute contralateral herniation following unilateral decompression:

• When evacuating the smaller hematoma first in bilateral cases, removing even modest mass effect can create a pressure gradient that precipitates acute herniation toward the newly decompressed side 1
• Evacuating the thicker hematoma first establishes a "safety buffer" by reducing the dominant mass effect before addressing the contralateral side 1
• This staged approach (thicker first, then thinner) allows for intracranial pressure equilibration between sides, minimizing herniation risk 1

Surgical Efficiency and Hemodynamic Stability

Starting with the thicker hematoma offers practical intraoperative advantages:

• Greater volume evacuation from the first burr hole provides more dramatic clinical improvement, which can stabilize the patient hemodynamically before proceeding to the second side 3, 4
• The thicker hematoma typically requires longer drainage time; addressing it first allows the drainage system to work while preparing the contralateral side 5
• In elderly or medically fragile patients, achieving maximal decompression early in the procedure is crucial if the operation must be abbreviated 3

Bilateral Hematoma-Specific Considerations

For bilateral chronic subdural hematomas specifically:

• Bilateral cases carry higher risk of intracranial hypertension compared to unilateral hematomas, making the sequence of evacuation more critical 1
• The principle mirrors bilateral tumor resection guidelines: when no preexisting neurological deficit exists, address the larger/more symptomatic lesion first to minimize risk of bilateral complications 1
• Staging the procedure (thicker first, thinner second) allows for compensation and reduces the risk of acute pressure dysregulation 1

Technical Execution

The practical approach should be:

• Perform preoperative CT measurement of maximum hematoma thickness on each side to definitively identify which side to address first 2, 4
• Position the patient to allow access to both sides, but prepare and drape the thicker side first 6
• Complete burr hole placement, irrigation, and drain insertion on the thicker side before proceeding to the contralateral burr hole 3, 4
• For bilateral cases, burr hole craniostomy remains the preferred technique over twist-drill, as it provides better drainage for thicker collections 6

Common Pitfalls to Avoid

• Never assume bilateral hematomas require simultaneous bilateral burr holes—the sequence matters for pressure dynamics 1
• Avoid starting with the "easier" or more accessible side if it is the thinner hematoma, as this prioritizes surgical convenience over patient safety 1
• Do not rely solely on symptom lateralization to choose which side to drain first, as bilateral hematomas often produce diffuse or non-lateralizing symptoms; use objective CT measurements 2, 4
• Be aware that rapid bilateral decompression can precipitate hypotension; starting with the thicker side and allowing brief equilibration before the second side may provide better hemodynamic stability 3