Chronic Subdural Hematoma- To Drain or Not to Drain?
Deepak Awasthi, MD, Jay Howington, MD and Greg Dowd, MD
Department of Neurosurgery
Louisiana State University Medical Center; New Orleans, Louisiana

[Abstract | Introduction | Case Ilustrations | Discussion | Conclusions | References]

Although chronic subdural hematoma (CSDH) is a well-known entity, the best means of its management remains controversial. Several cases of CSDHs have been treated recently at Louisiana State University Medical Center (LSUMC) and questions of symptomatic recurrence as well as usage of a drainage system have remained uncertain. These cases are briefly reviewed and the current literature analyzed to be able to answer these questions. In addition, the role of MRI in better defining these lesions is highlighted. The most important conclusions of this analysis are: 1. that with a closed system drainage the symptomatic recurrence rate is significantly lower than with burr-hole irrigation alone; 2. MR T1-weighted imaging (T1WI) is useful in predicting the propensity of CSDHs to recur- high intensity on T1WI predicts a significantly lower recurrence rate.

Chronic subdural hematoma (CSDH) is a well known as a curable disease in the elderly.(10,21) It can manifest with variable neurologic signs and symptoms including confusion, hemiparesis, seizures.(21) Treatment for this entity has remained controversial ranging from craniotomy to burr-hole irrigation with or without closed system drainage.(10,11,17,20,21,23) Despite these treatment possibilities, the recurrence rate for CSDHs ranges from 5% to 33% .(11,12,21,23) Can the recurrence rate be decreased with any one surgical technique? Are there any predictors for recurrence rate? This report attempts to answer these questions with case illustrations and review of the literature.

Case Illustrations:
Case 1
This 50 year old white man was found unresponsive at home. There was no evidence of trauma or reported trauma. On arrival to the emergency room (ER) he ws lethargic, but arousable and had left upper extremity weakness (2/5). No other neurological deficits. Pupils were equal and reactive. His cranial CT scan showed a chronic sudural hematoma with a small area of hyperintensity suggesting a more recent bleed (Figure 1).

Figure 1: Cranial CT scan of case 1 showing a left frontal chronic subdural hematoma with mass effect. Note the small hyperdensity (red arrow) near the edge of the collection. This case was managed with burr-hole irrigation and closed-system drainage with good results.

The patient underwent burr-hole irrigation followed by a closed system drainage for 48 hours. He made a good post-operative recovery with only a mild upper extremity weakness (4/5). He was fully awake and alert. At 6 month follow-up there is no evidence of recurrence.

Case 2
This 71 year old white woman with a history of an unknown pyschiatric disorder was brought to the ER from her nursing home with increasing confusion and delirium. She had no focal neurological deficits. All toxic and metabolic workup was normal. She had a MRI scan of the brain which revealed a hyperintense subdural collection on the T1- weighted as well as the T2-weighted MRI scan of the brain (Figure 2).

Figure 2: A (top pict): T1-weighted MR image (sagital view) showing the high-intensity subdural collection. B (bottom pict): T2-weighted MR image (axial view) also shows a high-intensity subdural collection with accompanying mass effect.

Neurosurgery was consulted for an "acute" subdural hematoma. Indeed this represented a chronic subdural hematoma as also seen on the cranial CT scan obtained in the ER (Figure 3).

Figure 3: Cranial CT scan of case 2 shows the chronic right-sided subdural hematoma with mass effect. This was seen as a high-intensity collection on aT1-weighted MR image (figure 2). This patient was successfully managed with burr-hole irrigation and closed-system drainage.

The patient underwent burr-hole irrigation followed by a closed system drainage. She made a very good post-operative recovery and was sent back to the nursing home awake and alert as well as fully oriented. She had no focal neurological deficits. Follow-up cranial CT scan at 9 months shows just a small amount of subdural fluid- no mass effect and asymptomatic.

Case 3
This 75 year old white woman presented to the neurosurgery clinic one month after a motor vehicle accident where she was a driver of a car hit on the driver's side. At that time there was no loss of consiousness, transient nausea and vomiting as well as frontal headaches which improved over a course of a week. A cranial CT scan at that time revealed a very small right-sided subdural hematoma with no mass effect (Figure 4).

Figure 4: Cranial CT scan of case 3 at time of head injury showing an inconsequential right-sided acute subdural hematoma (note the asymmetry on the right).

She was doing well until one week prior to admission from the clinic when the frontal headaches recurred and became constant. In addition, she had balance difficulty and increasing forgetfulness. A cranial CT scan one month after the injury revealed a chronic subdural hematoma on the right side (Figure 5).

Figure 5: Cranial CT scan performed one month after head injury in case 3 shows a large right- sided chronic subdural hematoma with mass effect.

She underwent burr-hole irrigation of the hematoma without any drainage system. Intraoperatively, the brain was seen to re-expand after irrigation of the CSDH. She did well postoperatively with improvement in the headaches and balance. At 8 month follow-up she continues to do well, no recurrence.

Case 4
This 56 year black woman presented to the ER with change in mental status (increase lethargy) and weakness of the right-side. Cranial CT scan showed a chronic left hemispheric subdural hematoma. She underwent burr-hole irrigation with no drainage system. Two days postop, she had a deterioriation in her mental status (increasing lethargy) with worsening right-sided hemiparesis. Followup cranial CT scan revealed recurrence of the subdural hematoma (figure 6) .

Figure 6: Cranial CT scan (after the burr hole irrgation) in case 4 showing the recurrent subdural collection with mass effect.

A craniotomy was performed with evacuation of subdural hematoma. She has made a slow recovery. She has required a tracheostomy and feeding tube and was transferred back to a nursing home facility


[Clinical Presentation | Treatment Options | Recurrence of CSDH | Not to Drain | To Drain]

Clinical Presentation:
The above cases illustrate the variable presentation of CSDHs. They can present spontaneously or several weeks to months after trauma (usually minor). As a matter of fact there usually is some history of trauma.(10) CSDHs can present as strokes, transient ischemic attacks (TIAs), headaches, memory changes, confusion, seizures, hemiparesis, monoparesis, tremors.(9,10,17,20,21) They have also been uncommonly known to present as Parkinsonism.(19) Indeed, CSDHs are a great "mimcker" of neurological disease of the late 20th century. Thus, they should be considered in the differential diagnosis of elderly patients presenting with neurological signs and symptoms. After the diagnosis (usually a cranial CT scan), the treatment of this entity remains controversial.(1,6,11,17,18,20,21,22,23,28)

Treatment Options:
Before the advent of CT scans, craniotomy was performed to evacuate these hematomas. Some authors still advocate a small craniotomy with or without membranectomy.(1,17) Sambasivan et al report a remarkable 30 year series of 2300 cases (since 1966) and advocate a small temporal craniotomy, with the dura left open and the subdural space communicating with the subtemporalis space.(17) This procedure, according to Sambasivan et al in India, has resulted in marked reduction of recurrence and membranectomy has not been required; only 0.5% mortality! (17) Despite these type of results, burr-hole irrigation is currently the most accepted treatment offered in CSDH.(1,11,23) In addition, several studies now advocate leaving a closed-system drainage after irrigation of the CSDH to improve outcome and lessen the chance of recurrence.(4,21,23) However, the use of a drainage system remains controversial.(11,21)
Several newer treatment options have also been discussed in the literature. Smely et al advocate a twist-drill trephination and a subdural catheter kit for evacuation of CSDHs.(18) In this study 33 patients with 36 CSDHs were treated with the subdural catheter kit (TDT) and compared to 33 patients treated with burr-hole irrigation and closed-system drainage (BHC) with 40 CSDHs. The re-operation rate was 18.1% in the TDT group and 33.3% in the BHC group along with a 18.1% infection rate in the BHC group (compared to 0% in the TDT group).(18) Yoshimoto et al advocate a small craniostomy at the superior lateral angle of the forehead just beneath the hair-line- no infections and recurrence rate of 10% or 2/20 cases.(28) Hellwig et al as well as Rodziewicz et al adovate endoscopic treatment of CSDHs, especially septated lesions.(6.16)
It is evident the goal of treatment is minimally invasive while at the same time preventing recurrences. The major debate arises whether one should leave a drain or not. In our 4 cases, 2 drains were used with good results. Although our follow-up is short, it is evident that a drainage system can be left in place with minimal morbidity. The only recurrence was in a patient with no drainage system. Nevertheless, before answering this controversial question, it will be helpful to see why even think about an option for a drain- to prevent recurrence!

Recurrence of CSDH:
The recurrence rate in the literature has varied from 5% to 33%.(11,12,21,23) It is important to emphasize that recurrence means symptomatic recurrence of the subdural hematoma at the site of previous surgery. Bleeding tendency, intracranial hypotension, repeated hemorrhage from neomembranes are well known risk factors for recurrence.(2,3,21) The persistence of the subdural space has been considered a risk factor for reaccumulation of hematoma (not necessarily symptomatic).(15) In addition, Fukuhara et al feel that mechanical properties of the brain- high surface elastance- can explain the tendency in some cases for poor re-expansion.(5) In addition, factors of elastance were considered to be the compressibility of cerebrovascular volume, the meningeal membranes, and the subpial brain tissue.(5,24) Some factors among these three may lead to poor re-expansion of brain.(5) However, extent of neomembranes and amount of primary cerebral expansion following decompression has not been shown clinically to affect outcome.(4,8) In these studies the neurological conditon on admission was the best predictor o outcome.(4,8)
Recently, Tsutsumi et al have shown that the appearance of the CSDH on the pre-operative MRI scan, T1-weighted image (T1WI) is a powerful predictor of recurrence.(21) For example, in their prospective randomized study of 257 consecutive patients, 199 patients were evaluated with a preoperative MR imaging.(21) They showed that the symptomatic recurrence rate of 3.45 in the high-intensity group (on T1WI) was significantly lower than the 11.6% rate in the non-high intensity group. In addition, the surgical procedures discussed in this study correlated with the MR findings- in the high-intensity group, 1.1% of CSDHs recurred in patients in whom closed system drainage was used and 11.1% in patients without closed system drainage.(2) In the cases discussed in the current report, one patient had a preoperative MR scan which revealed high-intensity on the T1WI (Figure 2). This patient did not have any recurrence.

Not To Drain:
It is argued that placing a drain can lead to complications without changing the rate of recurrence and/or clinical outcome.(1,11,13,14,18) These potential complications include brain injury, further hemorrhage from neomembranes, infection.(11,18) This brings us to why does the subdural hematoma recur- is it an oncotic or osmotic mechanism with accumulation of spinal fluid (11,25,26) or is it the result of repeated microhemorrhages from the neocapillary network in the outer neomembrane with aggravation by the fibrinolytic activity of fibrinogen degradation products(7)? If one accepts the second possibility, it may be argued that simple evacuation of the fibrinolytic agents would be sufficient means of definitive treatment of CSDHs, rendering unnecessary additional postoperative subdural drainage, with its risks mentioned above. However, depsite these arguments several authors have seen good results with drainage.(4,11,21,23) Even Markwalder et al advocate drainage despite their observation that long term results with and without drainage are identical.(11) This group feels that closed system drainage avoids the possibility of early postoperative deterioration probably due to subdural CSF accumulation.(11) This study, however, is retrospective as are several other studies.(4,11)

To Drain:
It is argued that placement of the drain can significanty diminish the rate of symptomatic recurrence and thus the need for re-operation.(4,11,21,23,27) Although several authors advocate drainage (4,11,27), there have been only a few attempts to clarify this question with prospective studies (21,23). Wakai et al report a prospective comparative study of 38 patients assigned sequentially to burr-hole irrigation with closed-system drainage group (20 patients) and irrigation without closed-system drainage group (18 patients).(23) In this study, the authors concluded that closed-system drainage after burr-hole irrigation significantly reduces the recurrence rate of CSDHs.(23) In a bigger, better designed and recent prospective randomized study it was clearly shown that closed-system drainage significantly reduced the rate of symptomatic recurrence of CSDHs.(21) In this study, the authors randomly assigned 257 consecutive adult patients with CSDHs into several groups, including two surgical groups: group 1 was one burr-hole irrigation of the hematoma cavity with closed-system drainage and group 2 was only one burr-hole irrigation with no drainage.(21) The recurrence rates following irrigation with and without closed system drainage were significantly different: 3.1% with closed system drainage and 17% following burr-hole irrigation alone.(21) In addition, there were no statistically significant differences between the two groups with regard to patient age, bilateral operations, suspected bleeding tendencies, or intensity on T1-weighted MR images.(21) Most of the drains in this study as well as other studies were kept in place for 1 day and as long as 3 days.(4,11,21,23,27)
An additional interesting finding in the Tsutsumi study is that approximately one-half of CSDHs appeared as homogeneous high-intensity areas on the T1WI suggesting transportation of plasma and/or CSF by chemical irritation of the hematoma as a possible mechanism (osmotic theory mentioned above) of enlargement of the CSDH.(21) Thus, in these cases drainage may become very important in preventing recurrences. On other hand, low or isointensity on T1-weighted MR imaging may suggest expansion by rebleeding from microvessels of neomembranes. This cases may be prone to recur regardless of operative methods and should be closely observed with serial CT scans or MR scans (if necessary).

Based on our case illustrations and the review of the literature, it is the authors' opinion that a closed system drainage should be used after burr-hole irrigation of a CSDH, if the brain does not re-expand. In addition, if possible a MRI scan should be obtained pre-operatively to help predict the propensity of recurrence and, at times, differentiate a CSDH from a subdural hygroma (which will follow CSF intensities on T1WI, unlike most CSDHs).


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