Acta Neurochirurgica

, Volume 159, Issue 11, pp 2033–2036 | Cite as

Post-operative seizures after burr hole evacuation of chronic subdural hematomas: is prophylactic anti-epileptic medication needed?

  • Gabriel Flores
  • Juan C. Vicenty
  • Emil A. Pastrana
Original Article - Brain Injury



There are limited data with regards to the associated risk of post-operative seizures in patients with surgically treated chronic subdural hematomas (CSDHs). The use of anti-epileptic drugs (AEDs) is associated with significant side effects.


A retrospective chart review was performed on patients operated via burr hole for CSDH in our institution from 2004 to 2013. Post-operative seizures at 1-year follow-up were identified. Demographic data, medical history, and imaging characteristics were recorded.


A total of 220 patients were included in the study. Post-operative seizures occurred in 2.3%. The mean time of onset of seizures was 8.4 days. No difference in age and gender between seizing and non-seizing groups was identified p > 0.05. Mean midline shift was 4.6 mm in seizing group vs. 4.2 mm in non-seizing group, p > 0.05. Mean thickness was 14.6 mm in patients without post-operative seizures and 18.4 mm in patients with post-operative seizures, p > 0.05. There was no significant difference in post-operative seizure incidence related to the side or location of the CSDHs.


The incidence of post-operative seizures in patients with CSDH evacuated via burr holes was low. Prophylactic AEDs should not be routinely administered if no other risk factor for seizure exists. Demographic and clinical factors did not appear to influence post-operative seizures.


Chronic Subdural Hematoma Seizures Prophylaxis Post-operative 


Chronic subdural hematomas (CSDHs) are one of the most common entities encountered by neurosurgeons worldwide. CSDHs often occur as sequelae of minor head trauma, or a traumatic head injury that causes an acute subdural hematoma that is unrecognized or treated non-surgically with later conversion into a CSDH.

The incidence of CSDHs increases with age, with a recent estimated incidence of 58/100,000/year for patients between 70 and 79 years old and 127.1/100,000/year in those over 80 years old [8, 9]. Treatment of symptomatic CSDHs remains standard, consisting of drainage via burr holes or craniotomy with or without a subdural drainage system [10]. However, controversy exists in the management of seizure prophylaxis and prevention of post-operative seizures following evacuation. Studies have shown that the incidence of post-operative seizures in patients with CSDHs range from 1 to 23.4% [5, 7].

In the management of neurosurgical patients, the prevention of seizures is important due to their negative impact on quality of life [1]. The onset of seizures in patients with CSDHs has been shown to greatly increase the incidence of subsequent seizures/epilepsy and the chance of secondary harm [11, 16]. Nonetheless, the administration of anti-epileptic drugs (AEDs) in the peri-operative period in patients with brain injury without a history of seizures has not been shown to prevent epileptogenesis [34, 14, 15, 17].

AEDs should not be disregarded as innocuous, especially in the elderly, who are usually predisposed to CSDHs. Differing metabolic profiles among patients may lead to an increased chance of toxicity, thus the administration of these medications should be done with the certainty that the occurrence of seizures will be prevented and that the overall benefit outweighs its risk, primum non nocere should always dictate our judgment.

The objective of our study was to investigate the occurrence of post-operative seizures in patients with chronic subdural hematomas treated with burr holes and its relations to pre-operative radiographic findings, morbidities and their follow-up, up to 1 year following intervention.

Materials and methods

A retrospective analysis of the surgical database of the Puerto Rico Medical Center was performed. Medical records of patients with CSDHs admitted to the adult neurosurgery service and treated via burr holes between July 2004 and July 2013 were examined. All patients underwent a standard procedure, which consisted of two burr holes with irrigation of normal saline until clear subdural fluid was seen to confirm maximal drainage, followed by subdural drain placement with an 8-French feeding tube catheter to gravity drainage. Post-operatively, patients were admitted to the intensive care unit, the subdural drain was left in place for 24 h and brain computer tomography (CT) was ordered to evaluate efficacy of subdural evacuation before drainage removal. No CT scans were ordered following drainage removal unless patients developed neurological deterioration. Patients did not receive either pre-operative or post-operative AEDs prophylaxis, and were followed in clinics 2 weeks post-operatively and every 3 months for up to 1 year. Occurrence of a seizure event was recorded and confirmed by history, and a baseline electroencephalography (EEG) was obtained to record any abnormal electrical activity, however EEG was not used to decide if a seizure event had occurred. If patients developed a seizure event they were managed with levetiracetam 1 g (g) twice daily and referred to the epilepsy service after appropriate studies were done to rule out a new surgical lesion. Exclusion criteria included: history of a seizure disorder, previous AEDs use, seizure episode secondary to metabolic disturbances and/or stroke, previous history of intra-parenchymal hemorrhage, traumatic sub-arachnoid hemorrhage or acute subdural hematoma within the past 12 months, and insufficient medical records to determine the presence/absence of seizures pre and post-operatively for up to 1 year. For each patient, age, sex, admission GCS score; dates of seizure events, and antiepileptic drug initiation were recorded. Patient medical histories were also reviewed for pre-operative morbidities. Admission brain CT scans were reviewed for imaging characteristics, including hematoma location, maximal thickness, and midline shift measurements. Institutional review board was obtained to perform study.

Seizure occurrence was identified through the careful analysis of the medical record, including admission history, daily progress notes, and discharge summaries. Statistical analyses were performed using Lilliefors’ composite goodness-of-fit test, Wilcoxon rank-sum test and Fisher’s exact test as appropriate. Statistical significance was defined as a p value <0.05.


Two hundred seventy six patients were identified for examination. Fifty-six patients were excluded due to a history of a seizure disorder (N = 10), previous AEDs use (N = 12), seizure episode secondary to metabolic disturbances and/or stroke (N = 7), previous history of intra-parenchymal hemorrhage, traumatic sub-arachnoid hemorrhage or acute subdural hematoma within the past 12 months (N = 12), or insufficient medical records (N = 15). Two hundred twenty patients were included in this study (Table 1). The mean age was 59 years, with 76% males and 24% females. Five patients (2.3%) developed post-operative seizures. Seven patients were lost to follow-up at 1 year, five patients died of unrelated causes, and two patients were unable to reach. All patients with post-operative seizures were male. The test for a difference in gender between patients with post-operative seizures and patients with no post-operative seizures was not significant (p = 0.337, Fisher’s exact test). The time to a seizure event was 8.4 days (mean), with a median of 7 days with a Gaussian distribution p = 0.5 (Lilliefors’ composite goodness-of-fit test). The longest time after surgery for seizure occurrence was 30 days, and at 1 year follow up no patients had another seizure episode. The age of patients with post-op seizures was 50.8 years (mean), with a median of 46 years. The age of patients without post-op seizures was 59.6 years (mean), with a median of 56 years. There is no statistically significant difference between the ages of those with and without seizures (p = 0.16, Wilcoxon rank-sum test). The median Glasgow Coma Score (GCS) score for patients without post-op seizures was 13. For those patients with post-op seizures, the median GCS score was 13. These are not statistically different (p = 0.74, Wilcoxon rank-sum test).
Table 1

Demographical data, radiological parameters


Post-op seizures (−)

Post-op seizures (+)

p value

No. of patients




Mean age

50.8 years

59.6 years










Left side




Right side




Mean thickness

14.6 mm

18.4 mm


Mean midline shift

4.6 mm

4.2 mm


GCS score




The mean thickness for patients without post-op seizures was 18.4 mm (mean) with a median of 15 mm. For those patients with post-op seizures, the mean thickness was 14.6 mm with a median of 13 mm. These are not statistically different (p = 0.052, Wilcoxon rank-sum test).

The location of the chronic subdural hematoma was on the left side in 116 patients and in the right side in 104 patients. For patients with post-operative seizures, location was on the right in two patients and on the left in three patients. CSDH location was not associated with an increase risk for post-operative seizures (p > 0.05).

The mean midline shift for patients without post-operative seizures was 4.6 mm (mean) with a median of 4 mm. For those patients with post-op seizures, the mean midline shift was 4.2 mm with a median of 5 mm. These are not statistically different (p = 0.90, Wilcoxon rank-sum test). No comorbidities or pre-existing illnesses were independent predictors of seizure occurrence in the post-operative period.

Recurrence of CSDH occurred in 13 patients (6%), and was treated with re-exploration of burr holes. No patients with recurrence of CSDH developed post-operative seizures.


The incidence of post-operative seizures in our series of patients was 2.3%. This is in contrast with reports of up to 12.5% in patients treated via burr holes [6]. Different surgical techniques and variations of the same techniques could account for such differences. It is important to not underestimate the irritative environment caused by blood products on the cortical surface. It is standard in our practice to obtain a through washout of blood products from the cortical surface, minimizing the effect of such irritants. Even then, subdural drains should be left in place for pneumocephalus and for fluid evacuation [13]. Some reports have advocated for decompression alone and gravity suction of blood products with closed drainage systems. We feel this seems to behest the real purpose of surgery and predispose patients to recurrences [2].

In our study we found no statistically significant difference in location of subdural hematoma with the occurrence of post-operative seizures. The literature seems to be inconsistent in terms of seizure predisposition secondary to the location of the CSDHs [6, 12]. In our cohort, all patients who developed post-operative seizures were males, in contrast to recent reports that showed a tendency towards the female gender in seizure occurrence [6]. We cannot say, however, that there is a statistically significant difference in gender representation, since there are fewer women overall in the study. Most important, due to the low occurrence of post-operative seizures, the administration of AEDs is unnecessarily taking into consideration the side effects of such medications in sharp contrast to previous publications [11].


In our cohort of patients with CSDHs evacuated via burr holes, we found the incidence of post-operative seizures to be low despite the avoidance of peri-operative AEDs. Also, patients’ demographic and clinical factors did not appear to significantly influence the occurrence of post-operative seizures. The routine administration of peri-operative AEDs must be carefully weighted in patients with CSDH undergoing burr hole evacuation if no risk factor for seizure exists.


Compliance with ethical standards

Conflict of interest

All authors certify that they have no affiliations

with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.

Ethical approval

All procedures performed in studies involving human

participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. For this type of study formal consent is not required


  1. 1.
    Chang EF, Potts MB, Keles GE, Lamborn KR, Chang SM, Barbaro NM et al (2008) Seizure characteristics and control following resection in 332 patients with low-grade gliomas. J Neurosurg 108(2):227–235CrossRefPubMedGoogle Scholar
  2. 2.
    Chari A, Kolias AG, Santarius T, Bond S, Hutchinson PJ (2014) Twist-drill craniostomy with hollow screws for evacuation of chronic subdural hematoma. J Neurosurg 121(1):176–183CrossRefPubMedGoogle Scholar
  3. 3.
    Christensen J (2012) Traumatic brain injury: risks of epilepsy and implications for medicolegal assessment. Epilepsia 53(Suppl. 4):43–47CrossRefPubMedGoogle Scholar
  4. 4.
    Glantz MJ, Cole BF, Friedberg MH, Lathi E, Choy H, Furie K et al (1996) A randomized, blinded, placebo-controlled trial of divalproex sodium prophylaxis in adults with newly diagnosed brain tumors. Neurology 46(4):985–991CrossRefPubMedGoogle Scholar
  5. 5.
    Grisoli F, Graziani N, Peragut JC, Vincentelli F, Fabrizi AP, Caruso G et al (1988) Perioperative lumbar injection of Ringer’s lactate solution in chronic subdural hematomas: a series of 100 cases. Neurosurgery 23:616–621CrossRefPubMedGoogle Scholar
  6. 6.
    Grobelny BT, Ducruet AF, Zacharia BE, Hickman ZL, Andersen KN, Sussman E et al (2009) Preoperative antiepileptic drug administration and the incidence of postoperative seizures following bur hole-treated chronic subdural hematoma. J Neurosurg 11(6):1257–1262CrossRefGoogle Scholar
  7. 7.
    Hirakawa K, Hashizume K, Fuchinoue T, Takahashi H, No-mura K (1972) Statistical analysis of chronic subdural hematoma in 309 adult cases. Neurol Med Chir (Tokyo) 12:71–83CrossRefGoogle Scholar
  8. 8.
    Karibe H, Kameyama M, Kawase M, Hirano T, Kawaguchi T, Tominaga T (2011) Epidemiology of chronic subdural hematomas. No Shinkei Geka 39(12):1149–1153PubMedGoogle Scholar
  9. 9.
    Kudo H, Kuwamura K, Izawa I, Sawa H, Tamaki N (1992) Chronic subdural hematoma in elderly people: present status on Awaji Island and epidemiological prospect. Neurol Med Chir (Tokyo) 32:207–209CrossRefGoogle Scholar
  10. 10.
    Mori K, Maeda M (2001) Surgical treatment of chronic subdural hematoma in 500 consecutive cases: clinical characteristics, surgical outcome, complications, and recurrence rate. Neurol Med Chir (Tokyo) 41:371–381CrossRefGoogle Scholar
  11. 11.
    Sabo RA, Hanigan WC, Aldag JC (1995) Chronic subdural hematomas and seizures: the role of prophylactic anticonvulsive medication. Surg Neurol 43:579–582CrossRefPubMedGoogle Scholar
  12. 12.
    Schneck MJ, Maheswaran M, Leurgans S (2004) Predictors of outcomes after nontraumatic subdural hematoma. J Stroke Cerebrovasc Dis 13:192–195CrossRefPubMedGoogle Scholar
  13. 13.
    Singh AK, Suryanarayanan B, Choudhary A, Prasad A, Singh S, Gupta LN (2014) A prospective randomized study of use of drain versus no drain after burr-hole evacuation of chronic subdural hematoma. Neurol India 62(2):169–174CrossRefPubMedGoogle Scholar
  14. 14.
    Temkin NR, Anderson GD, Winn HR, Ellenbogen RG, Britz GW, Schuster J et al (2007) Magnesium sulfate for neuroprotection after traumatic brain injury: a randomised controlled trial. Lancet Neurol 6(1):29–38CrossRefPubMedGoogle Scholar
  15. 15.
    Temkin NR, Dikmen SS, Wilensky AJ, Keihm J, Chabal S, Winn HR (1990) A randomized, double-blind study of phenytoin for the prevention of post-traumatic seizures. N Engl J Med 323(8):497–502CrossRefPubMedGoogle Scholar
  16. 16.
    Van Breemen MSM, Wilms EB, Vecht CJ (2007) Epilepsy in patients with brain tumours: epidemiology, mechanisms, and management. Lancet Neurol 6:421–430CrossRefPubMedGoogle Scholar
  17. 17.
    Wang HC, Chang WN, Chang HW, Ho JT, Yang TM, Lin WC et al (2008) Factors predictive of outcome in posttraumatic seizures. J Trauma 64:883–888CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag GmbH Austria 2017

Authors and Affiliations

  • Gabriel Flores
    • 1
  • Juan C. Vicenty
    • 1
  • Emil A. Pastrana
    • 1
  1. 1.Department of Surgery – Neurosurgery SectionUniversity of Puerto Rico – Medical Sciences CampusSan JuanPuerto Rico

Personalised recommendations