Decompressive Craniectomy for Poor-Grade Aneurysmal Subarachnoid Hemorrhage

Naoki Otani*, Kojiro Wada and Kentaro Mori

Department of Neurosurgery, National Defense Medical College, Japan

*Corresponding author: Naoki Otani, Department of Neurosurgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan

Received: April 05, 2014; Accepted: May 05, 2014; Published: May 06, 2014

Abstract

Patients with poor-grade aneurysmal subarachnoid hemorrhage (SAH) frequently suffer devastating sequelae caused by the primary and secondary impacts on the brain, particularly if associated with large intracerebral hematoma, sylvian hematoma, or acute subdural hematoma, which result in poor outcomes due to the significant brain stem compression caused by the mass effect. Decompressive craniectomy (DC) is known to reduce the morbidity and mortality in critically ill patients with massive ischemic infarction and severe head injury. However, the role of DC in the treatment of SAH patients is not fully understood. Several experimental studies have indicated that DC significantly improves outcome due to increased intracranial pressure or reduced perfusion pressure. Clinical reports about the efficacy of DC for poor–grade aneurysmal SAH are reviewed here.

Keywords: Brain stem compression; Massive ischemic infarction; Subarachnoid hemorrhage; Cerebral angiography; Intracranial hypertension

Introduction

Poor–grade aneurysmal subarachnoid hemorrhage (SAH) is a frequently devastating condition due to the primary and secondary impacts on the brain, particularly if associated with large intracerebral hematoma (ICH), sylvian hematoma, or acute subdural hematoma (ASDH), which result in poor outcomes due to the significant brain stem compression caused by the mass effect. Decompressive craniectomy (DC) is known to reduce the morbidity and mortality in critically ill patients with massive ischemic infarction [1–4] and severe head injury [5,6]. However, the role of DC in the treatment of poor–grade SAH remains obscure. Recent studies suggested that DC with dural plasty intended to enlarge the intracranial space allows the swollen cerebral hemisphere to expand out of the normal cranial limits, thus avoiding progression of brain herniation, which results in both improvement of cerebral compliance and decrease in intracranial pressure (ICP), and rises in both cerebral blood flow and cerebral microvascular perfusion, possibly accompanied by elevation in brain tissue oxygen [7–9]. Therefore, DC might be an effective strategy for poor–grade SAH [10–12]. The present study reviewed experimental and clinical reports about the efficacy of DC for patients with poor–grade aneurysmal SAH.

Representative Case and Case Series

A 57–year–old man suffered sudden onset of headache with loss of consciousness. Computed tomography (CT) scan on admission showing diffuse SAH with ICH (Figure 1A,1B). Three dimensional CT angiogram revealing a large aneurysm at the internal cerebral artery (ICA) bifurcation. The patient underwent aneurysm clipping with primary DC (Figure 1E). Two days after the operation, the brain edema had progressively worsened, on the other hand, midline shift and brain stem compression improved (Figure 1C, 1D). The patient recovered with Glasgow Outcome Scale score of Moderate disability(MD). In addition, one hundred and twenty three consecutive patients with poor–grade SAH (grades IV and V) were treated in our hospital. We retrospectively reviewed the hospital records including medical charts, operative records, and radiological findings. Thus, we divided the clinical outcomes of the patients into four groups with or without DC in grade IV and V. Patient outcome was assessed on discharge using Glasgow Outcome Scale that comprises five levels: good recovery (GR), moderate disability (MD), severe disability (SD), vegetative state (VS), and death (D). The clinical findings summarized in Table 1, which showed that favorable outcome increased after DC (Figure 2).

Table 1: Clinical characteristics of 123 patients who treated in poor-grade SAH.



  
    
    
    Grade    IV
    Grade V
  
  
    
    
    DC (-)
    DC (+)
    DC (-)
    DC (+)
  
  
    Patient    number
    
    19
    32
    24
    48
  
  
    Age
    
    37-77
    35-72
    35-75
    30-74
  
  
    mean
    
    59.4
    56.6
    57.8
    56.8
  
  
    Gender
    Male
    5
    13
    14
    19
  
  
    Female
    14
    19
    10
    29
  
  
    Site
    R
    11
    20
    12
    21
  
  
    L
    8
    12
    12
    27
  
  
    Aneurysm    size
    Small
    17
    28
    20
    42
  
  
    Medium
    2
    2
    2
    3
  
  
    Large
    0
    2
    2
    3
  
  
    Re-rupture
    
    1
    5
    3
    7
  
  
    Intraoperative    rupture
    
    1
    5
    3
    5
  
  
    Hypothermia    therapy
    
    0
    4
    2
    12
  
  
    Aneurysm    site
    ICA
    4
    7
    5
    13
  
  
    MCA
    13
    23
    10
    32
  
  
    AcomA
    2
    2
    9
    3
  
  
    Hematoma    volume (mm³)
    
    38.8
    39.6
    39.3
    41.5
  
  
    Midline    shift (mm)
    
    4.33
    7.81
    6.28
    8.5
  
  
    Basal    cistern effacement
    Yes
    2
    3
    2
    3
  
  
    
    No
    17
    29
    22
    45
  
  
    Brain    swelling
    
    3
    13
    16
    35
  
  
    DC: Decompressive    Craniectomy; ICA: Internal Carotid Artery; MCA: Middle Cerebral Artery; AcomA:    Anterior Communicating Artery



Table 1: Clinical characteristics of 123 patients who treated in poor-grade SAH.

Figure 1: A 57-year-old man suffered sudden onset of headache with loss of consciousness. CT scan on admission (A, B) showing diffuse subarachnoid hemorrhage (SAH) with intracerebral hematoma. Three dimensional CT angiogram revealing a large aneurysm at the internal cerebral artery bifurcation. The patient underwent aneurysm clipping with primary decompressive craniectomy (E). Two days after the operation, the brain edema had progressively worsened, on the other hand, midline shift and brain stem compression improved (C, D). The patient recovered with Glasgow Outcome Scale score of Moderate disability (MD).



Figure 1: A 57-year-old man suffered sudden onset of headache with loss of consciousness. CT scan on admission (A, B) showing diffuse subarachnoid hemorrhage (SAH) with intracerebral hematoma. Three dimensional CT angiogram revealing a large aneurysm at the internal cerebral artery bifurcation. The patient underwent aneurysm clipping with primary decompressive craniectomy (E). Two days after the operation, the brain edema had progressively worsened, on the other hand, midline shift and brain stem compression improved (C, D). The patient recovered with Glasgow Outcome Scale score of Moderate disability (MD).

Figure 2: Clinical outcomes for poor-grade SAH patients (grades IV and V) divided into four groups with or without DC in our hosipital, showing that favorable outcome increased after DC. D: death, PO: Poor Outcome, FO: Favorable Outcome.



Figure 2: Clinical outcomes for poor-grade SAH patients (grades IV and V) divided into four groups with or without DC in our hosipital, showing that favorable outcome increased after DC. D: death, PO: Poor Outcome, FO: Favorable Outcome.

Discussion

Surgical outcome in poor–grade aneurysmal SAH patients

Previous analysis has revealed that intraoperative aneurysm rupture has no impact on the outcome in patients with good or poor initial condition. Initial clinical grades IV and V as well as initial Fisher grades III and IV were strongly associated with poor outcome [13]. In addition, the presence of intracerebral or intraventricular hemorrhage has been identified as one of the common factors to influence the outcome [14,15]. Early aggressive surgery and intensive care for SAH patients in poor clinical condition can improve the mortality and morbidity [16–18]. Despite recent advances in the treatment of poor–grade SAH, the surgical outcome continues to be unfavorable in many patients because of uncontrollable intracranial hypertension. Increased ICP is associated with several detrimental effects such as cerebral ischemia following reduced perfusion pressure [19]. Intractable intracranial hypertension is associated with poor outcome among patients with poor–grade aneurysmal SAH [20– 23]. Therefore, immediate and continued effective ICP management is associated with improved outcome [16].

Pathophysiology of poor–grade SAH with hematoma

The clinical outcome for SAH patients with ICH is usually worse than that for SAH patients without ICH [16,24,25]. ICP increased in over half of all patients with SAH, particularly among those with poorgradeSAH and ICH [26]. On the other hand, the clinical outcome for SAH patients with ICH does not significantly differ from that of SAH patients without associated hematoma [27]. The incidence of rebleeding in patients with poor–grade SAH is 22% with ICH and 14% without ICH. Clinical grades on admission were significantly higher and outcome at 6 months after onset was less favorable in patients with poor–grade SAH with ICH than in those without ICH. Larger ICH was associated with worse clinical grade and less favorable outcome. The sites of the hematoma and ruptured aneurysm were closely correlated. The poor outcome of patients with ICH seems to be related to the severity of clinical grade on admission. However,the two groups did not significantly differ in terms of managementand surgical outcome for the same clinical grades [28]. Initial brain damage caused by ICH and subsequent brain edema seemed to be the main cause of disability, and might be related to the poor clinical outcome. Intracranial hypertension in patients with SAH can be associated with deleterious changes, which might have profound impacts on outcome [29]. Consequently, aggressive clot evacuation and aneurysm obliteration are recommended. Rapid control of ICP has been associated with improved outcome, indicating that early control of ICP and cerebral blood flow is important to improve outcome or to counteract deterioration. The management of SAH patients depends on the prevention of secondary brain damage. High ICP within the fixed volume of the skull can lead to secondary brain damage, herniation, and permanent neurological damage, or even death. Severe malignant vasospasm may develop and become resistant to conventional medical treatments in some patients. For these reasons, new additional therapeutic strategies such as DC are essential to improve the clinical outcome in patients with poor–grade SAH.

Efficacy and pathophysiology of DC

DC is a neurosurgical procedure which is intended to treat high ICP. DC includes removal of the calvarial bones to create free space which the brain can occupy under the scalp, aiming to minimize ischemic damage by increasing cerebral blood flow [30–33]. Recent clinical findings suggest that external decompression might reduce ICP [34–37]. Craniectomy and enlarged dural plasty induce a significant decrease in ICP and increase in cerebral tissue oxygenation [35,36]. External decompression may also significantly increase cerebral tissue oxygenation [34,37]. In addition, clinical studies have suggested that DC results in significant elevation of mean cerebral blood flow velocity and significant decreases in the MCA pulsatility index values, indicating reduction in cerebrovascular resistance in most patients with traumatic brain swelling [24,38]. Recent studies suggested that DC with dural augmentation enlarges the intracranial space so that the swollen cerebral hemisphere could expand out of the normal cranial limits, thus avoiding progression of brain herniation. The gain in intracranial volume results in both improvement of cerebral compliance and decrease in ICP; the latter favors increases in both cerebral blood flow and cerebral microvascular perfusion, which can be accompanied by higher brain tissue oxygen tension as well as the normalization of abnormal metabolic parameters in patients with cerebral ischemia [7–9]. Therefore, DC can induce immediate reduction in ICP and control the ICP elevation that occurs several days after SAH. Surgical outcome improves in cases with controlled ICP by DC, compared with cases with uncontrolled ICP [26,27]. In particular, delayed swelling can induce elevated ICP, which can be confused with the symptoms of vasospasm. Therefore, early DC would be useful to avoid this clinical problem.

Surgical outcome of DC for SAH

Recent clinical studies have found that DC can improve the surgical outcome of patients with poor–grade SAH and massive ICH [10–12]. The surgical outcome was improved by ICP control in a series of 8 patients with poor–grade MCA aneurysmal SAH and sylvian hematoma treated with external decompression, resulting in a favorable outcome rate of 62.5% compared with a poor outcome rate of 37.5% [12]. External decompression resulted in favorable outcome rates of 33% in grade IV and 40% in grade V patients with sylvian hematoma [11]. Long–term outcome was better for patients who underwent secondary DC within the first 48 hours after SAH [39]. DC can be a life–saving procedure which provides a better outcome in patients with cerebral infarction secondary to vasospasm and SAH [40]. DC was most beneficial if performed immediately after the detection of resistant increase in ICP in patients younger than 60 years old, suggesting that early intervention may have a great influence on the outcome [40]. Although DC has prolonged the short–term survival of patients with poor–grade SAH and ICH, the overall quality of life experienced by survivors remains poor [10]. Further investigation is required to clarify long–term outcomes with particular focus on higher cerebral function.

DC for SAH with ASDH

The incidence of aneurysmal SAH associated with ASDH is between 0.5% and 7.9% [24,41] and leads to a poor clinical outcome [42,43]. SAH patients with ASDH have a poorer prognosis compared to SAH patients without ASDH [44]. The poor outcome in SAH patients with ASDH seems to be related to the severity of the clinical grade on admission. Initial brain damage caused by ASDH, and the subsequent brain edema, seem to be the main causes of disability, which is closely related to the poor clinical outcome. Therefore, aggressive clot evacuation and aneurysm obliteration are recommended for rapid control of the ICP, which is associated with improved outcome. Early control of the ICP and cerebral blood flow is important for improving the outcome and to prevent deterioration. In general, patients with aneurysmal SAH and ASDH tend to have a worse prognosis compared to SAH patients without ASDH [20]. If patients with aneurysmal ASDH suffer no primary damage to the brain tissue, the prognosis seems to be more favorable if adequate diagnostic investigations and prompt aggressive treatment are performed. The poor outcome in patients with ASDH seems to be due to the initial elevated ICP caused by the ASDH. Despite recent advances in the treatment of patients with poor–grade SAH, surgical outcome remains generally poor because of the uncontrolled intracranial hypertension. Elevated ICP has been associated with several detrimental effects, such as cerebral ischemia and reduction of the cerebral blood flow [20]. In previous series, the mortality rate was 21% and the poor prognosis rate was 42% in patients with aneurysmal SAH and ASDH [45]. Favorable outcome was achieved in 41.7% of SAH patients with ASDH who underwent primary DC [46]. Therefore, rapid DC will be useful for controlling the ICP, thus improving the outcome and decreasing the mortality rates in such patients.

DC for SAH with massive hematoma

Recent clinical studies have reported that DC can be useful to improve the surgical outcome in patients with poor–grade SAH and massive ICH [10,11,34,36]. Surgical outcome was improved by ICP control in a small series of 8 patients with poor–grade MCA aneurysmal SAH and sylvian hematoma treated with external decompression [12]. Favorable outcome was achieved in 5 of the 8 patients and poor outcome in 3 patients. Favorable outcome rates were 33% in grade V patients and 40% in grade IV patients with sylvian hematoma treated with external decompression [11]. Similarly, favorable outcome was obtained in 56.0% of grade IV patients after treatment which included decompression [47]. The ICP remained below 20 mmHg for 7 days after surgery in all patients with favorable outcome, but tended to remain at or over 20 mmHg after surgery in the patients with poor outcome. In addition, the ICP remained over 25 mmHg in the patients who died. Favorable outcomes were found in 52.6% of cases after 12 months [48]. Similarly, good outcome was obtained in 37.5% of patients compared to overall 26.6% in all craniectomy patients at 6 months [49]. These findings suggested that patients with progressive cerebral edema may benefit most from secondary DC after SAH. DC prolonged the short–term survival of patients with poor–grade SAH with ICH, but the overall quality of life for survivors was still poor. Increased ICP refractory to standard treatment in a patient with SAH can lead to poor outcome and mortality. Several studies found that DC significantly improves outcome due to increased perfusion pressure or reduced ICP. We suggest that DC helps to reduce morbidity and mortality through control of elevated ICP in patients with poor–grade SAH. However, further investigation is required to clarify the value of DC for treating poor–grade SAH from the viewpoint of long–term higher cerebral function.

References

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Citation: Otani N, Wada K, Mori K. Decompressive Craniectomy for Poor-Grade Aneurysmal Subarachnoid Hemorrhage. Austin Neurosurg Open Access. 2014;1(2): 1006.

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