Keywords:
hematoma, subdural - recurrence - trephining
Palavras-chave:
hematoma subdural - recidiva - trepanação
Chronic subdural hematoma (CSDH) is characterized by a chronic deposition of clot
in the subdural space, usually with favorable prognosis[1],[2]. It is a frequent neurosurgical condition, commonly associated with a previous history
of trauma[3]. There is a variable incidence between 5.3 and 13.5 patients per 100,000 people
per year, with a higher prevalence in the elderly[4],[5].
The main risk factors involved are advanced age, male gender, alcoholism and coagulopathies,
including therapeutic anticoagulation and antiplatelet therapy[1],[2],[6]. Its treatment may be conservative or surgical, depending on symptoms and clot size[3],[7]. Morbidity and mortality are low, however complications and recurrence are common[7],[8], especially when conditions such as older age, impairment of consciousness, midline
shift, postoperative residual hematoma and comorbidities are present[9].
In surgical cases, several techniques may be applied: one or two burr holes with or
without the use of a drain; “twist drill craniostomy”, craniotomy, and “endoscopic
burr hole”[3],[10]. Although there is no consensus on the best surgical technique to be employed[7],[11],[12], burr hole evacuation of the hematoma has been the most frequently-used procedure
and is considered the first option for treatment for CSDH[11],[12],[13],[14],[15].
Burr holes, when associated with the use of a drain, have potentially better outcomes[15],[16]. However, the literature is still divergent regarding the number of burr holes and
the use of the drain[17],[18],[19].
The present study aimed to evaluate whether the use of a drain and/or the number of
burr holes for the treatment of a chronic subdural hematoma modifies the rates of
recurrence and complications.
METHODS
A retrospective review of the patients operated on because of a CSDH in a single center
(Hospital do Servidor Público Estadual de São Paulo) between 2006 and 2015 was carried
out.
The project was approved by the Ethics and Research Committee.
Sample
One hundred fifty-five (155) surgeries in 155 patients were evaluated. Twelve patients
were lost to follow-up and one patient had a craniotomy as the primary surgery. A
total of 142 patients were finally evaluated. Follow-up time ranged from three to
21 months, with an average of 7.67 months.
Forty-two patients (29.5%) were female and 100 (70.4%) were male. Among the women,
the mean age was 73 ±11.4 years old. The mean age in the male group was 72.7 ± 12.8
years old. Twenty-two patients (15.4%) were less than 60 years old; 45 patients (31.7%)
were 60-74 years old and 75 patients (52.8%) were 75 years or older (73 ±12.4 years
old).
Primary outcomes
The presence of recurrence and complications and the postoperative functional status
(Glasgow Outcome Scale - GOS) were evaluated in patients submitted to one or two burr
holes and the use, or not, of a drain, and correlated with potential factors for recurrence,
including: anthropometric data (age and gender), comorbidities, laterality of the
hematoma (uni or bilateral), functional scales (American Society of Anesthesiologists
(ASA) Score and GOS), one or two burr holes and the use, or not, of the drain.
Patients were divided by age into three groups: less than 60 years old, between 60
and 74 years old and those over 75 years old.
Comorbidities (surgical risk assessed by ASA), use of antiplatelet drugs or anticoagulants,
alcoholism, and preoperative Glasgow Coma Scale (GCS) were recorded. The ASA surgical
risk classification is a widely-used scale to classify surgical patients. A score
of ASA 1 is a healthy patient with no organic changes; ASA 2 is a patient with mild
or moderate systemic alteration; ASA 3 is a patient with severe systemic alteration
with functional limitation; ASA 4 is a patient with severe systemic alteration representing
life risk; and ASA 5 is a dying patient who is not expected to survive without surgery[20].
Surgical technique
The burr holes created were either frontal or parietal or both, respectively at the
Stephanion and Eurion craniometric points. In all procedures, additional irrigation
with 0.9% saline was performed. The choice of the number of burr holes and the use,
or not, of a drain was made by the surgeon, depending on the size and extent of the
clot and the intraoperative findings.
Statistics
Data were described in absolute numbers and percentages. Numerical data were described
by means and standard deviations. Evaluation of the association between recurrence
and complications with or without the drain, number of burr holes, demographic and
surgery data was performed using the c2 test, with Yates correction, when appropriate. The level of significance determined
for the study was p ≤ 0.05. When the values for statistical analysis were zero, they
were replaced by 0.5 for statistical calculation.
RESULTS
Among the men, 17 (17%) presented with CSDH recurrence and six (6%) presented with
complications. Five women (11.9%) presented with CSDH recurrence and none had complications.
There was no significant difference between recurrence (χ2 = 0.44, p = 0.47) and complication rate (χ2 = 0.20, p = 0.79) with respect to gender.
Among the patients under 60 years of age, four were reoperated on (18.2%) and none
had complications. In the 60 to 74 years age group, seven (15.5%) presented with CSDH
recurrence and one (2.2%) presented with complications. There were 11 recurrences
(14.6%) and 5 (6.6%) complications in the group of patients over 75 years old. There
were no differences between the age group and reoperation rates (χ2 = 0.92, p = 0.31) and complications (χ2 = 0.28, p = 0.43).
Presenting symptoms were: motor deficit in 56 patients (39.4%), headache in 13 patients
(9.1%), impaired consciousness in 12 (8.4%), aphasia in 7 (4.9%), seizure in 5 (3.5%)
and sensory deficit in 1 (0.7%). The GCS score at the entrance to the emergency room
ranged from 7 to 15, with a mean of 14.
Seventeen patients reported a chronic use of alcohol. Of these, three presented with
a recurrence of CSDH (3/17) and one presented with CSDH complications (1/17). Twelve
patients (8.4%) were classified as ASA 1; 112 (78.8%) as ASA 2; 15 (10.5%) as ASA
3; 3 (2.1%) as ASA 4; and no patients as ASA 5.
Nineteen recurrences and four complications occurred in patients classified as ASA
≤ 2, three recurrences and two complications in ASA> 2. There was no difference among
ASA groups and the number of reoperations (χ2 = 0.88, p = 0.27) or complications (χ2 = 0.12, p = 0.72).
Thirty-seven patients had bilateral CSDH (26%). There were 105 (73.9%) patients with
unilateral CSDH. Among the unilateral patients, 86 (81.9%) were operated on with a
single burr hole, and 19 (18%) were operated on with two burr holes. Seventy-four
(70.4%) used a drain and 31 (29.5%) did not ([Table]). Among patients with bilateral CSDH, 12 (32.4%) patients were operated on with
a single burr hole of each side and 25 (67.5%) were operated on with two burr holes.
Twenty-two (59.4%) patients used drains and 15 (40.6%) did not ([Table]).
Table
Surgical data of unilateral and bilateral chronic subdural hematoma.
|
Variable
|
Unilateral chronic subdural hematoma
|
Bilateral chronic subdural hematoma
|
|
Drain
|
p
|
Burrhole
|
p
|
Drain
|
p
|
Burrhole
|
p
|
|
With
|
Without
|
One
|
Two
|
With
|
Without
|
One
|
Two
|
|
n
|
74
|
31
|
|
86
|
19
|
|
22
|
15
|
|
12
|
25
|
|
|
Recurrence
|
16.2%
|
9.6%
|
0.73
|
12.8%
|
21.1%
|
0.56
|
13.6%
|
26.7%
|
0.6
|
8.3%
|
24%
|
0.69
|
|
Complication
|
2.7%
|
6.4%
|
0.55
|
23.2%
|
10.5%
|
0.52
|
9.1%
|
0
|
0.42
|
0
|
8%
|
0.48
|
At the end of the follow-up, three patients (2.1%) were classified as GOS 3; 20 as
GOS 4 (14.1%); 119 as GOS 5(84%) and no patients as GOS 1 or 2.
The total number of recurrences was 22 (15.5%) and the total number of complications
was 6 (4.2%). Chi-square tests did not reveal statistically significant differences
in recurrence rates according to the use, or not, of a subdural drain and the number
of burr holes used in surgery ([Table]).
DISCUSSION
Chronic subdural hematoma is one of the most frequent diagnoses in neurosurgery[1],[2],[3]. It is characterized by an intracranial hemorrhage with a history of trauma in 50%
of patients and occurs predominantly in males and in the elderly[7],[10],[20],[21].
Its incidence has increased considerably due to population aging[21], reaching 58 patients per 100,000 people in those aged 65 years old or more[4]. Most patients have complete remission of symptoms when diagnosed and treated early[22],[23],[24].
Conditions such as the use of anticoagulants and anti-platelets, chronic alcohol use
and the use of cerebrospinal fluid shunts (ventriculoperitoneal shunts) increase both
the incidence and rates of complications and recurrences[25],[26],[27], and may be important determinants of patient prognosis.
In this study, there was a higher prevalence of CSDH in males (70.42%) and in those
older than 60 years of age (84.5%), with a mean age of 73 years. Epidemiological profiles
were similar to those expected, with the exception of the mean age being greater than
usually observed (63 years old)[2],[7]. Presenting symptoms were, respectively, motor deficit (39.4%), headache (9.1%)
and impairment of consciousness/mental confusion (8.4%), all in agreement with those
described in the literature[3],[27].
Surgical treatment is the best therapeutic option for CSDH[10]. Several techniques are described in the literature (burr hole or craniotomy). There
is still insufficient scientific evidence to justify the choice of the best technique[20],[21],[22],[23]. Since it is a procedure with few operative risks and with good efficacy, a burr
hole has been the preferred choice for most neurosurgeons[25],[26],[27], and is the most-used technique.
A burr hole is associated with reoperation rates ranging from 9.25% to 26.5%[16]. There is disagreement concerning the number of burr holes and possible outcomes[7]. According to Taussky et al.[19], rates of recurrence and complications were considerably lower in patients operated
on with two burr holes (p <0.001). Nevertheless, most of the studies did not show
significant differences between the use of one or two burr holes[22],[23],[24].
The pathophysiology of CSDH consists of repeated microbleeding of bridging veins after
traumatic injury, mainly in atrophic elderly brains. In the young, they are more frequently
associated with higher energy trauma or coagulopathies. Initial bleeding leads to
inflammation and subsequent formation of a capsule with vascular neoformation, which
may then bleed, increasing the size of the hematoma. Surgery consists of opening the
capsule and removing the clot. The use of a drain potentially removes residual bleeding
after the burr hole and decreases the number of recurrences. The available data suggest
better results with the use of the drain[13],[14],[15],[16],[17]. However, in our sample there was no difference with or without drain usage.
There was no association among any of the predictor factors studied and the presence
of complications, which occurred in six out of 142 patients.
There were no statistically significant differences among the recurrence rate and
any of the other predictors.
Some limitations should be described. Firstly, this was a retrospective study and
thus some biases of data harvest and follow-up of patients may be missing or incomplete.
Secondly, outcomes of patients with CSDH are complex and also depend on several clinical
and neurological features, not only the neurosurgical technique and strategies.
In conclusion, the number of burr holes and the use of a drain to treat CSDH did not
alter the rates of recurrence and complications.
