What are the outcomes of a burr hole procedure for subdural hematomas?

Burr Hole Procedure Outcomes for Subdural Hematomas

Burr hole drainage for chronic subdural hematomas achieves excellent outcomes in approximately 90% of patients, with low mortality (3-4%) and recurrence rates of 9-13%, making it a highly effective first-line surgical intervention.

Mortality and Survival Outcomes

• Perioperative mortality ranges from 3.4% in modern series, representing a significant improvement over conservative management for symptomatic hematomas 1
• For symptomatic subdural hematomas requiring drainage in the context of spontaneous intracranial hypotension, burr hole drainage is recommended when there is significant mass effect, with small or asymptomatic hematomas managed conservatively 2

Functional Recovery and Quality of Life

• Excellent functional outcomes (minimal or no deficit) occur in 90% of patients at 6-week follow-up after single or double burr hole evacuation 3
• Fair outcomes occur in 5.5% and poor outcomes in 4.5% of cases 3
• Immediate neurological improvement is commonly observed, even in elderly patients with severe deficits such as hemiparesis and confusion 4

Recurrence and Reintervention Rates

• Hematoma persistence or recurrence occurs in 9-13% of cases, requiring reintervention 1, 3
• The reintervention rate is approximately 9.3%, with most cases (8.2%) managed by repeat trepanation and only 1.1% requiring craniotomy 1
• Twelve of 111 patients (10.8%) required postoperative re-evacuation, either by needle aspiration or reoperation through the burr hole, with only one patient requiring craniotomy 3

Complication Rates

• Overall complication rate is approximately 10.9% with modern techniques 1
• Postoperative seizure rate is 6.6% 1
• Infection rate is low at 1.6%, including both superficial wound infections (3 cases) and deep infections (1 case) 1
• The use of subperiostal (extracranial) drainage systems may reduce seizure risk and limit secondary infection spread compared to drains in direct contact with the hematoma capsule 1

Technical Considerations Affecting Outcomes

• Closed-system suction drainage through a single burr hole provides superior outcomes compared to open drainage or no drainage, with shorter hospital stays and lower complication rates 5
• Double burr hole trepanation with subperiostal passive closed-drainage is technically easy, highly effective, safe, and cost-efficient 1
• Burr hole evacuation without drainage carries risk of early postoperative clinical deterioration in some patients, though long-term outcomes are similar to drained cases 6
• The procedure can be safely performed under local anesthesia in elderly or high-risk patients, making it accessible even in resource-limited settings 4

Important Caveats

• Early postoperative clinical deterioration (within 24 hours) may occur more frequently in undrained cases compared to those with closed-system drainage, though this does not affect long-term outcomes 6
• Closed-system drainage is advisable to avoid early deterioration, except when technically difficult to install (such as with considerable perioperative cortical expansion) 6
• The single burr hole technique with saline irrigation addresses brain decompression, removal of semisolid hematoma components, and dilution of endogenous fibrinolytic agents 3

Comparison with Other Surgical Approaches

• For intracerebral hemorrhage (not subdural hematoma), the STICH trial showed that noncraniotomy approaches had worse outcomes than conservative management (OR 1.3,95% CI 0.78-2.35), though this may reflect selection bias toward patients with deep hemorrhages and poor neurological condition 2
• Endoscopic aspiration via burr hole for intracerebral hemorrhage reduced mortality from 70% to 42% at 6 months, with benefits mainly in lobar hematomas and patients <60 years of age 2