Cranioplasty after Decompressive Craniectomy: The Effect of Timing on Postoperative Complications

Abstract

Decompressive craniectomy (DC) due to intractably elevated intracranial pressure mandates later cranioplasty (CP). However, the optimal timing of CP remains controversial. We therefore analyzed our prospectively conducted database concerning the timing of CP and associated post-operative complications. From October 1999 to August 2011, 280 cranioplasty procedures were performed at the authors' institution. Patients were stratified into two groups according to the time from DC to cranioplasty (early, ≤2 months, and late, >2 months). Patient characteristics, timing of CP, and CP-related complications were analyzed. Overall CP was performed early in 19% and late in 81%. The overall complication rate was 16.4%. Complications after CP included epidural or subdural hematoma (6%), wound healing disturbance (5.7%), abscess (1.4%), hygroma (1.1%), cerebrospinal fluid fistula (1.1%), and other (1.1%). Patients who underwent early CP suffered significantly more often from complications compared to patients who underwent late CP (25.9% versus 14.2%; p=0.04). Patients with ventriculoperitoneal (VP) shunt had a significantly higher rate of complications after CP compared to patients without VP shunt (p=0.007). On multivariate analysis, early CP, the presence of a VP shunt, and intracerebral hemorrhage as underlying pathology for DC, were significant predictors of post-operative complications after CP. We provide detailed data on surgical timing and complications for cranioplasty after DC. The present data suggest that patients who undergo late CP might benefit from a lower complication rate. This might influence future surgical decision making regarding optimal timing of cranioplasty.

Introduction

D ecompressive craniectomy (DC) is often performed as a potential life-saving procedure in patients suffering from elevated intracranial pressure (ICP) because of brain swelling due to traumatic brain injury (TBI; Bullock et al., 2006), cerebral infarction (Schwab et al., 1998; Vahedi et al., 2007), subarachnoid hemorrhage (SAH; Güresir et al., 2008,2009a,2009b), intracerebral hemorrhage (ICH) (Güresir et al., 2008), and for other reasons (Güresir et al., 2010). The broader range of indications for DC implies a growing number of subsequent cranioplasty (CP) procedures in survivors. Indications for CP are usually protective and cosmetic (Winkler et al., 2000). Besides these, CP has been reported to facilitate neurological recovery and to improve cerebral blood flow, cerebrospinal fluid (CSF) hydrodynamics, and metabolic activity after decompressive craniectomy (Fodstad et al., 1984; Winkler et al., 2000). On the other hand, some other authors reported a considerably higher overall complication rate after CP compared to other elective cranial procedures (Chang et al., 2010; Gooch et al., 2009). Despite possible residual brain swelling after DC, several reports questioned the traditional delayed timing of cranioplasty (3–6 months after DC), and suggested cranial repair at an early stage in terms of better neurological outcome (Beauchamp et al., 2010; Liang et al., 2007; Yadla et al., 2011). Early CP within 2 months after DC has been previously reported to be safe in patients with TBI (Liang et al., 2007). However, the timing of cranioplasty with regard to post-operative complications remains controversial. We therefore analyzed our prospectively conducted database of consecutive patients undergoing DC and subsequent CP, with special attention to the timing of CP and its associated post-operative complications.

Methods

From October 1999 to August 2011 we performed 280 cranioplasty procedures in patients who previously underwent DC. Information, including patient characteristics on admission and during the course of treatment, radiological features, mean duration of the DC and CP procedures, the modality of DC, the presence of ventriculoperitoneal (VP) shunt, complications of DC and CP, and the specific indication for DC, were prospectively entered into a computerized SPSS-database (version 15; SAS Institute Inc., Chicago, IL). Initial DC was performed for intractably elevated ICP (>20 mm Hg, despite extensive medical therapy) in acute situations or during the course of intensive care treatment. The size of DC was at least 11×16 cm. The site of the DC was determined based on the location of the main pathology and/or mydriasis. During DC, the dura was opened in a stellate fashion but no watertight duraplasty was applied, as previously reported in detail elsewhere (Güresir et al., 2010). Cranioplasty was considered after resolution of brain edema. Antiplatelet drugs, when used, were withdrawn 10 days prior to surgery.

The timing of CP varied according to the treating neurosurgeon, due to unclear literature data, between early and late. Based on the treating neurosurgeon's personal experience, some preferred to always perform CP early (≤2 months), while others performed it always late (>2 months). Based on previously published reports we defined the cut-point for early and late cranioplasty at 2 months after the initial DC (Liang et al., 2007). Patients were stratified into two groups according to the timing of CP, as early (≤2 months) versus late (>2 months).

Cranioplasty

Immediately after DC, the removed bone flap was frozen and stored under sterile conditions at −80°C. During cranioplasty, the layer for replacement of the bone fragment was dissected between the myocutaneous flap and the dura-like layer covering the brain. The bone margins encasing the craniectomy defect were exposed. The autologous bone flap was fixed with titanium plates and screws. The temporalis muscle was dissected as a separate layer and fixed at the bone flap. All patients received a single intravenous dose of an antibiotic agent and a wound drain. In patients with borderline hydrocephalus, a lumbar drain was inserted before cranioplasty, and was removed after the procedure. If unexpected bulging of the brain beyond the bone margins occurred intraoperatively and no lumbar drain had been inserted preoperatively, a ventricular puncture was performed intraoperatively in order to insert the bone flap smoothly without force. Postoperatively, a routine CT scan was performed to rule out procedure-related complications and to confirm correct positioning of the bone flap.

Complications of CP requiring surgical intervention were assessed and analyzed.

Statistical analysis

Data analyses were performed using the computer software package SPSS (version 15; SAS Institute Inc., Chicago, IL). An unpaired t-test was used for parametric statistics. Categorical variables were analyzed in contingency tables using Fisher's exact test. Results with p<0.05 were considered statistically significant. In a second step a multivariate analysis was performed to find independent predictors for post-operative complications after CP using a binary logistic regression analysis, and to find confounding factors between potentially independent predictors. Variables with significant p values in univariate analyses, or that had been considered to be clinically relevant, were considered as potentially independent variables in the multivariate analysis. A backward stepwise method was used to construct multivariate logistic regression models with the inclusion criterion of a p value of <0.05.

Results

Patient characteristics

Patient characteristics, including age, sex, and data on the DC and CP procedures according to the primary admission diagnosis are shown in Table 1.

Table 1.

Patient Characteristics in the Present Series

Variable	TBI	Infarction	SAH	ICH	Other	All
No. of CP	98	80	73	20	9	280
Mean age in years	38±19	54±12	48±11	44±17	40±12	46±16
Female sex	31%	40%	75%	50%	78%	48%
Mean time to CP in days	91±49	110±72	105±75	117±70	121±89	103±67
Mean duration of CP in min	124±36	104±25	113±42	121±39	115±28	115±36
Hemicraniectomy	73	80	65	19	6	243
Bifrontal craniectomy	25	-	8	1	3	37
VP shunt	20	7	28	7	2	64
Complications	21	8	8	8	1	46

Values represent the number of procedures unless otherwise indicated. Means are given with standard deviations (SDs).

CP, cranioplasty; VP, ventriculoperitoneal; TBI, traumatic brain injury; SAH, subarachnoid hemorrhage; ICH, intracerebral hemorrhage.

Cranioplasty was performed in 98 patients (35%) with previous TBI, 80 patients (29%) with previous cerebral infarction, 73 patients (26%) with previous SAH, 20 patients (7%) with previous ICH, and in 9 patients (3%) with other primary diagnoses.

Cranioplasty was performed in 243 patients (87%) with hemicraniectomy, and in 37 patients (13%) with bifrontal craniectomy.

Complications of cranioplasty

Overall 46 of the 280 patients (16.4%) had CP-related complications. Complications of CP included epidural or subdural hematoma (EDH or SDH) in 17 (6%), wound healing disturbance in 16 (5.7%), abscess in 4 (1.4%), hygroma in 3 (1.1%), CSF fistula in 3 (1.1%), and bone flap dislocation in 3 (1.1%) patients (Table 2).

Table 2.

Postoperative Complications Of Cranioplasty

Complication	TBI (n=98)	Infarction (n=80)	SAH (n=73)	ICH (n=20)	Other (n=9)	All (n=280)
EDH or SDH	5 (5.1)	4 (5)	3 (4.1)	4 (20)	1 (11.1)	17 (6)
Wound healing disturbance	9 (9.1)	2 (2.5)	4 (5.4)	1 (5)		16 (5.7)
Abscess	3 (3.1)	1 (1.25)				4 (1.4)
Hygroma	2 (2)			1 (5)		3 (1.1)
CSF fistula	1 (1)	1 (1.25)		1 (5)		3 (1.1)
Other	1 (1)		1 (1.4)	1 (5)		3 (1.1)

Values represent number of complications (%).

EDH, epidural hematoma; SDH, subdural hematoma; CSF, cerebrospinal fluid; TBI, traumatic brain injury; SAH, subarachnoid hemorrhage; ICH, intracerebral hemorrhage.

The initial modality of DC (hemicraniectomy versus bifrontal craniectomy) had no effect on post-operative complications (16.9% versus 13.5%; p=0.8, OR 0.8, 95% CI 0.3,2.1). Because of the lack of effect of the DC modality on post-operative complications, the following univariate and multivariate analyses were performed on pooled data of patients with previous hemicraniectomy and bifrontal craniectomy.

The presence of a VP shunt was associated with a significantly higher rate of complications after CP compared to patients without a VP shunt (28.1% versus 12.9%; p=0.007, OR 2.7, 95% CI 1.3,5.2). Hygroma developed after cranioplasty in 3 of 64 patients (4.7%) with a VP shunt, and in 0 of 216 patients (0%) without a VP shunt (p=0.01, OR 24.6, 95% CI 1.3,484).

Patients who underwent DC due to TBI suffered significantly more often from wound healing disturbances and abscess following cranioplasty than patients who underwent DC because of any other primary diagnosis (12.2% versus 4.4%; p=0.03, OR 3.04, 95% CI 1.2,7.7).

Time to cranioplasty

The mean time from DC to CP was 103±67 days. The mean time to cranioplasty did not differ significantly between patients after stratification according to underlying pathology previously leading to DC. The mean surgical time for cranioplasty was 115±36 min (Table 1).

The effect of timing of CP on post-operative complications

CP was performed early in 54 patients (19.3%) and late in 226 patients (80.7%) after DC.

Stratified according to the timing of the cranioplasty procedure, EDH or SDH occurred in 3 out of 54 patients after early CP, and in 14 out of 226 patients when CP was performed late after initial DC (5.5% versus 6.2%). Furthermore, wound healing disturbance occurred in 7 out of 54 patients after early CP, and in 9 out of 226 patients after late CP (13% versus 4%; Table 3). Fifty percent of patients with complications after early CP suffered from TBI as an underlying pathology (Table 4).

Table 3.

Time of Cranioplasty

	No. of complications according to the time to cranioplasty
Total	≤2 months (n=54)	>2 months (n=226)
Complications	14 (25.9)^a	32 (14.2)^a
EDH or SDH	3 (5.5)	14 (6.2)
Wound healing disturbance	7 (13)	9 (4)
Abscess	1 (1.85)	3 (1.3)
Hygroma	1 (1.85)	2 (0.9)
CSF fistula	1 (1.85)	2 (0.9)
Other	1 (1.85)	2 (0.9)

p=0.04, OR 2.1, 95% CI 1.04,4.3.

Values represent the number of complications (%).

EDH, epidural hematoma; SDH, subdural hematoma; CSF, cerebrospinal fluid; CI, confidence interval.

Table 4.

Patient Characteristics and Complications after Cranioplasty

	Time to cranioplasty
	≤2 months			>2 months
	All	No complication	With complication	All	No complication	With complication
No. of CPs	54	40	14^*	226	194	32^*
Mean age in years	39±19	38±18	41±23	47±15	49±14	41±17
Female sex	46%	48%	43%	48%	51%	34%
Mean time to CP in days	43±15	41±15	46±14	117±66	120±69	103±41
Mean duration of CP in min	110±40	104±34	123±51	116±35	117±33	108±45
Hemicraniectomy	45	34	11	198	168	30
Bifrontal craniectomy	9	6	3	28	26	2
VP shunt	15 (27.7)	9 (22.5)	6 (42.9)^**	49 (21.7)	37 (19.1)	12 (37.5)^**
Etiology
TBI	29 (53.7)	22 (55)	7 (50)	69 (30.5)	55 (28.4)	14 (43.7)
Infarction	7 (12.9)	4 (10)	3 (21.4)	73 (32.3)	68 (35)	5 (15.6)
SAH	12 (22.2)	10 (25)	2 (14.3)	61 (27)	55 (28.4)	6 (18.8)
ICH	5 (9.3)	3 (7.5)	2 (14.3)^***	15 (6.6)	9 (4.6)	6 (18.8)^***
Other	1 (1.9)	1 (2.5)		8 (3.6)	7 (3.6)	1 (3.1)

p=0.04; OR 2.1, 95% CI 1.04,4.3.

p=0.007; OR 2.7, 95% CI 1.3,5.2.

***

p=0.01; OR 3.4, 95% CI 1.3,9.2.

Values represent the number of complications unless otherwise indicated (%). Means are given with standard deviations.

CP, cranioplasty; VP, ventriculoperitoneal; TBI, traumatic brain injury; SAH, subarachnoid hemorrhage; ICH, intracerebral hemorrhage.

Overall, early CP after DC was associated with a significantly higher rate of complications compared to late CP (25.9% versus 14.2%; p=0.04, OR 2.1, 95% CI 1.04,4.3; Tables 3 and 4).

Brain swelling

During four CP procedures (1.4%) we were forced to abort and postpone the cranioplasty procedure due to unexpected brain swelling intraoperatively. In 3 of 54 patients with early CP (5.5%) versus 1 of 226 patients with late CP (0.4%), the procedure had to be aborted and postponed (p=0.02). Intraoperative puncture of the ventricles to release CSF was necessary in 59 of 280 CP procedures (21%). Also, 14 of 54 patients (26%) with early and 45 of 226 patients (20%) with late CP required intraoperative ventricular puncture (p=0.4).

Multivariate analysis

We performed a multivariate logistic regression analysis of those variables significantly associated with complications after CP. We also included the variable “intraoperative ventricular puncture” for further analysis, to determine any possible association with higher post-operative complications. In the multivariate regression model the variables “early CP” (p=0.03, OR 2.2, 95% CI 1.1,4.6), “presence of VP shunt” (p=0.01, OR 2.3, 95% CI 1.2,4.7), and “ICH as underlying pathology” (p=0.01, OR 3.4, 95% CI 1.3,9.2) remained significant for the occurrence of post-operative complications after CP (Nagelkerke's R²=0.1).

Discussion

Decompressive craniectomy for intractable ICP elevation mandates later cranioplasty. The optimal timing of the cranioplasty procedure after decompressive craniectomy remains controversial. We therefore analyzed 280 cranioplasty procedures performed at our institution with regard to the occurrence of post-operative complications after cranioplasty. The results of the present study suggest that patients who underwent cranioplasty late (>2 months) after DC, might benefit from a significantly lower complication rate. Several reports stated that the overall complication rate of cranioplasty is much higher than for other elective cranial procedures (Chang et al., 2010; Gooch et al., 2009; Güresir et al., 2010). However, cranioplasty has been reported to improve cerebral blood flow, CSF hydrodynamics, and metabolic activity after decompressive craniectomy (Fodstad et al., 1984; Winkler et al., 2000). Because of the potential benefit of these improvements for patient rehabilitation, a number of reports discussed early timing of cranioplasty (Beauchamp et al., 2010; Kilincer et al., 2005; Liang et al., 2007; Sarov et al., 2010; Schiffer et al., 1997; Tabaddor and LaMorgese, 1976; Waziri et al., 2007). Because of controversial data in the literature regarding the timing of CP and post-operative complications, we performed a retrospective analysis of our prospectively collected data concerning the occurrence of complications after cranioplasty and the timing of the procedure.

Complications after cranioplasty

In this series and throughout the literature, complications of CP exceed those of other elective cranial procedures. The overall complication rate after cranioplasty was 16.4% in our patient population. Chang and associates recently published a series with an overall complication rate of 16% following CP (Chang et al., 2010). Gooch and colleagues reported complications after CP requiring surgical treatment in 16 of 109 patients (14.7%; Gooch et al., 2009). Upon analysis of the complications after CP, wound healing disturbances and post-operative abscess following CP occurred more often in patients with previous TBI compared to the group of all patients undergoing DC due to any other primary diagnosis (12.2% versus 4.4%). This might be because patients after TBI are commonly admitted with injuries to the skin leading to secondary infections or contamination (Rish et al., 1979).

Gooch and associates stated that patients undergoing bifrontal craniectomy are at significantly higher risk for post-operative complications after CP (Gooch et al., 2009). However, our data suggest no significantly increased risk for complications in patients treated with bifrontal craniectomy (16.9% versus 13.5%). A delayed time to cranioplasty was previously linked with the development of persistent hydrocephalus requiring shunt placement (Waziri et al., 2007). Recently, Rahme and colleagues concluded that hydrocephalus does not frequently occur after DC (Rahme et al., 2010). In contrast to the data published by Chang's group, we identified the presence of a VP shunt as a factor associated with complications after CP (p=0.007; Chang et al., 2010). Post-operative hygroma was only observed in patients with VP shunt (p=0.01). The ability to potentially avoid shunt-related complications by adjusting the valve to a higher setting is an advantage for the use of programmable shunts, and might suggest preoperative raising of the opening pressure for prophylactic reasons (Zemack and Romner, 2000). Because of this advantage, the use of programmable shunts might be considered in patients who underwent DC and who require placement of a VP shunt.

The effect of timing of CP on post-operative complications

The timing of cranioplasty has been discussed controversially. Recently, several reports argued that patients might benefit from early CP (Beauchamp et al., 2010; Chang et al., 2010; Liang et al., 2007). Liang and associates stated that cranioplasty following DC at an early stage (5–8 weeks after DC) is safe and might lead to neurologic improvement (Liang et al., 2007). However, their report lacked detailed information about the complication rates after cranioplasty. Chang and colleagues reported that patients who underwent cranioplasty in an early stage exhibited lower complication rates (Chang et al., 2010). Gooch and co-workers did not find significantly increased complication rates in cranioplasty when performed in an early stage (0–48 days), and found no association between the timing of CP and post-operative complications in general (Gooch et al., 2009). In our opinion it is remarkable that patients who underwent craniectomy for the purpose of decompression could undergo CP as early as 0 days, which might promote doubt about the indications for DC. Beauchamp and associates suggested that CP could be performed in patients with TBI within 2–6 weeks after the initial DC, with no increased rate of infection (19%), or hydrocephalus (Beauchamp et al., 2010). In a recently published review, Yadla and colleagues reported no effect of early surgery, method of bone flap preservation, or implant material used, on post-operative complications after CP (Yadla et al., 2011).

However, the results of our analysis showed a significantly higher complication rate of cranioplasty when performed within 2 months after the initial DC (25.9% versus 14.2%; p=0.04). In our series, 53.7% of patients with early CP suffered from TBI versus 30.5% of patients with late CP. The higher infectious complication rate of patients with TBI may have altered the overall complication rate in the early and late CP groups. However, TBI was no significant predictor of post-operative complications after CP in our multivariate analysis, and therefore no confounder in the comparison of early versus late CP. In the multivariate analysis, early CP, the presence of a VP shunt, and ICH as underlying pathology were significantly associated with post-operative complications after CP. Despite the possible neurological improvements seen after early CP in some patients (Chang et al., 2010; Liang et al., 2007), patients with late cranioplasty might benefit from a lower post-operative complication rate, which is higher compared to other standard elective cranial procedures. Considering the post-operative complication rate, the optimal time point of CP in the present series was after 2 months. The optimal time frame might be between 2 and 6 months in order to enhance rehabilitation and neurological recovery after CP, and to attain the lowest possible complication rate.

Complications after early CP may be due to residual brain swelling, risk of infection in traumatic injuries, or general brain vulnerability in severely ill patients. In 4 patients (1.4%), we were forced to abort and postpone the CP procedure due to unexpected residual brain swelling intraoperatively. The CP procedure was significantly more often aborted and postponed when the attempt to CP was performed early (p=0.02). It has been reported that multiple alterations persist for several days, even after mild cerebral concussion, and represent the pathological basis of post-traumatic brain vulnerability (Vagnozzi et al., 2005; Yoshino et al., 1991). Vagnozzi and colleagues found that 30 days were needed for normalization of cerebral metabolism after mild trauma (Vagnozzi et al., 2008). Two recent studies indicated that neurometabolite concentrations are systematically altered even by mild TBI, and that these changes normalize over a time frame of 3–5 months after injury (Gasparovic et al., 2009; Yeo et al., 2010). Furthermore, in cases of severe TBI, this period of cerebral derangement might be prolonged. Therefore, a CP performed early might interfere during this window of elevated brain vulnerability, which could be an explanation for the increased post-operative complication rate seen with early CP.

Limitations

The present study has several limitations. Data analysis was retrospective, despite the fact that collection of data was prospective. Therefore the study suffers from the shortcomings of a retrospective analysis. The heterogeneity of the underlying pathologies that led to DC might have biased the complication rate after CP. Furthermore, these results represent only a single-center experience. However, our standardized surgical approach and the large number of patients may outweigh some of these shortcomings.

Conclusion

We provide detailed data on surgical timing and complications for cranioplasty after decompressive craniectomy. The present data suggest that early cranioplasty within 2 months is associated with a significantly higher risk of complications. Therefore, the timing of the CP procedure, its potential benefits when performed early, and the risks for the patient, should be calculated in each individual case.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

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