CASE REPORT/CASE SERIES
Acute Global Ischemic Stroke After Cranioplasty Case Report and Review of the Literature Erwin Mangubat, MD and Sepehr Sani, MD
Introduction: Cranioplasty procedures are performed usually after devastating neurological injuries requiring craniectomies. Although relatively safe, global intracerebral infarction is a poorly understood, and most often, lethal complication after cranioplasty. We report here one such case with a thorough literature review with insight as to possible etiologies of this injury. Case Report: A 14-year-old girl underwent a left-sided decompressive hemicraniectomy for treatment of a subdural hematoma and cerebral edema. The patient’s neurological condition eventually improved and she presented for cranioplasty repair of the defect 83 days after her initial operation. Six hours after an uneventful procedure, the patient’s neurological examination declined. Immediate CT scan revealed global edema. Despite all treatment measures, the patient progressed to global ischemia and brain death and expired. Conclusions: Although global intracerebral infarction after cranioplasty is extremely rare, the concepts of vessel injury, venous stasis, and reperfusion into dysfunctional cerebral tissue after cranioplasty should be considered when evaluating the risk of this procedure. Key Words: cranioplasty, complications, stroke, global ischemia
(The Neurologist 2015;19:135–139)
A
n increasing number of cranioplasty procedures are performed in neurosurgical practice mainly for cosmetic and protective purposes. Neurological improvement has been reported, possibly attributed to improvements in cerebral blood flow and metabolism after such a procedure.1–5 Particularly in cases of sinking flap syndrome (a phenomenon of paradoxical herniation that is theoretically a result from a mismatch of atmospheric pressure and forces of gravity being greater than intracranial pressure), cranioplasty has been attributed with further neurological improvement through increased bilateral hemispheric cerebral blood flow.6,7 However, complications after cranioplasty are not uncommon. Infection, wound dehiscence, intracerebral hemorrhage, hygroma, subgaleal collections, bone resorption, break-through seizures, neurological deficits, and hydrocephalus have been reported in 16% to 34% of studied patients.8–12 Global intracerebral infarction after cranioplasty is a rare devastating complication that is poorly understood, of which there are only 4 other reported cases to date.13,14 We report here the case of a 14-year-old girl with left-sided traumatic brain injury who developed bilateral supratentorial and From the Department of Neurosurgery, Rush University Medical Center, Chicago, IL. The authors declare no conflict of interest. Reprints: Sepehr Sani, MD, Department of Neurosurgery, Rush University Medical Center, 1725 West Harrison Street, Suite 855, Chicago, IL 60612. E-mail: [email protected]. Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 1074-7931/15/1905-0135 DOI: 10.1097/NRL.0000000000000024
The Neurologist
Volume 19, Number 5, May 2015
infratentorial hemorrhagic strokes with rapid progression to brain death. An extensive literature review and discussion regarding possible etiologies are provided.
CASE REPORT A 14-year-old girl who was a victim of pedestrian versus motor vehicle accident with an initial Glasgow coma scale (GCS) of 5 underwent a left-sided decompressive hemicraniectomy for treatment of a subdural hematoma and cerebral edema (Fig. 1A). The patient’s neurological condition eventually improved to GCS 9 and she presented for cranioplasty repair of the defect 83 days after her initial operation. The patient’s preoperative CT scan revealed encephalomalacia in the left posterior temporooccipital region and a paradoxical midline shift from left-to-right measuring 1.9 cm (Fig. 1B). A custom synthetic porous PEEK (polyether ether ketone) implant was implanted uneventfully. Postoperatively, the patient was noted to be at neurological baseline and CT revealed reexpansion of the left hemisphere associated with a parafalcine subdural hematoma and numerous petechial subcortical intracranial hemorrhages (Figs. 2A, B). Six hours later, the patient’s neurological examination declined and began to develop hypotension requiring intravenous pressors. Immediate CT obtained (Figs. 2C, D) revealed diffuse supratentorial and infratentorial cerebral edema with effacement of sulci, basal cisterns, gray-white junction, and increasing lateral and third ventricular sizes. CT angiography (CTA) of the head revealed diffuse narrowing in the vessels of the anterior and posterior circulation, likely reflecting attenuation due to diffuse cerebral edema. CTA of the neck demonstrated an intimal flap with focal out-pouching in the distal cervical portion of the right internal carotid artery, which was not flow limiting and was stable as compared with a CTA done at the time of initial trauma (Fig. 3). CT venogram of the head demonstrated a filling defect in the left sigmoid sinus and distal aspect of left transverse sinus (Fig. 4), as well as poor opacification in the superior sagittal sinus likely related to sluggish flow. Because of worsening ventriculomegaly, the ventricular peritoneal shunt was externalized at the bedside and converted into an external ventricular drain with opening pressure >20 cm H2O. Despite continuous cerebrospinal fluid drainage, intracranial pressure remained >50 mm Hg. Follow-up CT scan 10 hours postoperatively (Figs. 2E, F) revealed diffuse hypodensities and hemorrhagic foci in bilateral hemispheres and brainstem. The patient shortly thereafter progressed to brain death and expired.
DISCUSSION Acute global hemorrhagic ischemia is a rare but devastating complication after cranioplasty. Review of 4 cases13–15 previously reported along with the presented report suggests a phenomenology that begins immediately in the postoperative period with a malignant and rapid course leading to diffuse and irreversible edema and brain death (Table 1). Previous heroic attempts at performing bilateral supratentorial and infratentorial craniectomies have proven futile, suggesting that the underlying mechanism is ischemic in origin rather than neurogenic or vasogenic edema. www.theneurologist.org |
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FIGURE 1. Noncontrasted CT head (A) demonstrates a left subdural hematoma with diffuse cerebral edema immediately after the patient’s traumatic injury. Three-month status postoperative left hemicraniectomy noncontrasted CT head (B) demonstrates an associated paradoxical midline shift to the right.
There are a number of proposed mechanisms that may have resulted in this devastating complication: (1) hypotensive event, (2) intraoperative vascular insufficiency, (3) venous stasis, (4) a “hyperperfusion congestion,” and (5) dysautonomia. The clearest explanation for this catastrophic event could be as a result of severe hypotension, leading to a severe anoxic brain injury with massive cerebral edema. Although anesthesia records did not show evidence of perioperative systemic hypotension, the patient did suffer a brief period of hypotension requiring vasopressors several hours after surgery. However, this is unlikely the causative event, as demonstrated on the immediate postoperative CT scan, there had already been signs of reexpansion and cerebral edema. In addition, even prolonged hypotensive episodes more often result in classic watershed infarcts rather than immediate global cerebral edema. Intraoperative vascular insufficiency may have also been a factor caused by positional stenosis or dissection of vessels related to positioning in the operating room. The patient did suffer a right-sided cervical internal carotid artery dissection upon her initial injury. However, CTA evidence demonstrated a non–flow-limiting stable lesion. Moreover, the patient did not have evidence of vertebral artery injury that would explain the posterior circulation ischemia. In addition, positioning for the patient was done in a manner such to limit the need to turn her head to no more than 20 degrees during surgery. As described by Chitale et al,13 deep venous occlusion can lead to diffuse cerebral edema, infarcts, and hemorrhagic conversion resulting in a similar clinical picture. The CT venogram in our patient did show some slowing of the left transverse sinus venous sinus, but no definitive occlusion or thrombosis. Moreover, this unilateral transverse sinus finding
136 | www.theneurologist.org
is unlikely sufficient to account for the global ischemia suffered by this patient and may be rather an anomaly as a result of the associated massive cerebral edema. Another possible causal mechanism may be associated with reexpansion of intracerebral tissue in the presence of a chronically dysfunctional brain related to impaired cerebral autoregulation, impaired tissue compliance from shuntdependent hydrocephalus, and sunken flap syndrome. This may have lead to a “hyperperfusion congestion”-like syndrome that could have caused global cerebral ischemia, resulting in multiple areas of petechial hemorrhage, in turn, leading to secondary neurogenic edema, herniation, and death. Following cranioplasty in patients with sunken flap syndrome, increased global cerebral blood flow has been demonstrated in a number of diagnostic tools, such as transcranial Doppler ultrasonography, xenon CT, and dynamic CT perfusion.6,10 This increase in cerebral perfusion, which in many patients would be associated with neurological improvement, may be detrimental in those patients with severe cases of cerebral autoregulation impairment.16 Cerebral blood flow autoregulation describes the complex intrinsic ability of the brain to maintain a stable cerebral blood flow by constantly changing cerebral vascular resistance despite fluctuations in arterial blood pressure and cerebral perfusion pressure.17–20 In the acutely injured brain, cerebral autoregulation may be dysfunctional, leading to episodes of hypoperfusion or hyperemia.21,22 Sudden increases in mean arterial blood pressure can be more easily transmitted into the microcirculation and can contribute to either areas of infarction or secondary hemorrhages and edema.23 In adults, the incidence of impaired cerebral autoregulation is 28% after moderate and 67% after severe traumatic brain injury.24,25 In the
Copyright
r
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The Neurologist
Volume 19, Number 5, May 2015
Global Stroke After Cranioplasty
FIGURE 2. Immediate postoperative left cranioplasty noncontrasted CT head demonstrates reexpansion of the left hemisphere associated with parafalcine subdural hematoma (A) and subcortical petechial hemorrhages (B). C and D, Six hours status postcranioplasty noncontrasted CT head demonstrates diffuse supratentorial and infratentorial cerebral edema with effacement of the sulci, basal cisterns, loss of gray-white junction, and increased bilateral and third ventricular sizes. E and F, Ten hours postoperative follow-up CT scan demonstrates diffuse hypodensities and hemorrhagic foci in bilateral hemispheres and brainstem.
pediatric population, impaired cerebral autoregulation has been found in 17% after mild and 42% after severe traumatic brain injury.26,27 Furthermore, the degree of impairment in children Copyright
r
may be worse as compared with that in adults. Vavilala et al28 observed that adolescents have a slightly delayed return of cerebral blood flow in response to transient hypotension.
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Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
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FIGURE 3. CT angiography of the neck immediately status post the patient’s initial traumatic injury demonstrates a non–flow-limiting carotid dissection (A), which is stable as compared with the CT angiography done status postcranioplasty (B). Arrows indicate area of dissection.
As Chitale et al13 described, a theoretical chain of events would begin with reequilibration of brain pressure vectors by removal of atmospheric pressure vector that would result in brain reexpansion after cranioplasty coupled with perfusion increases. Such movement may result in the stretch of
FIGURE 4. CT venogram of the head demonstrates a filling defect in the left sigmoid sinus and distal aspect of the left transverse sinus (arrow).
138 | www.theneurologist.org
supratentorial, infratentorial, and perforator intracranial vessels, resulting in a transient decrease in perfusion and microvascular injury, increasing the propensity for hemorrhage. Eom et al15 propose that the rapid increase in bilateral cerebral blood flow and volume in a chronic dysfunctional brain may result in venous stasis and congestion that can lead to thrombosis and diffuse hemorrhagic infarcts. Reexpansion may lead to compression of PCA vessels on the incisura, leading to large territory infarctions. In addition, this increase in cerebral perfusion may have increased the risk of hemorrhage into already weak brain tissue with impaired autoregulation. Furthermore, such a rapid reexpansion could have involved areas such as the hypothalamus that may cause dysautonomia, leading to changes in cerebral perfusion pressure. Therefore, for those who have suffered a severe head injury necessitating a hemicraniectomy, it may be useful to understand a patient’s cerebral autoregulatory capability before undergoing cranioplasty, particularly in those patients with sunken flap syndrome and/or hydrocephalus where tissue compliance is in question. Unfortunately there are no goldstandard methods to assess cerebral autoregulation. One modality currently used in clinical practice to assess cerebral autoregulation is pressure reactivity index (PRx) monitoring, which is defined as the correlation coefficient between slow waves in ICP and arterial blood pressure. PRx describes cerebral vasoreactivity and the level of disturbance in physiological vascular responses to changes in mean arterial blood pressure.9 Although such data obtained may not necessarily
Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
The Neurologist
Volume 19, Number 5, May 2015
Global Stroke After Cranioplasty
TABLE 1. Reported Cases of Global Cerebral Ischemia After Cranioplasty
Age/Sex
Cause/Site of Initial Injury
Paradoxical Cerebral Herniation
Shunt Dependent Hydrocephalus
Timing of Cranioplasty (d)
1
22/M
Trauma/bifrontal
N/A
Yes
88
Autologous Death
2 3 1
16/M 16/M 64/M
Trauma/bifrontal Trauma/bifrontal CVA/right
N/A N/A Yes
Yes Yes No
70 80 1y
Autologous Death Autologous Death PEEK Death
1
14/F
Trauma/left
Yes
Yes
83
References Number Honeybul et al14 Chitale et al13 This study
Type of Implant
PEEK
Result
Death
CVA indicates cerebrovascular accident; F, female; M, male; PEEK, polyether ether ketone.
change surgical management, it would at the very least provide insight to which patients are at risk of suffering such a catastrophic neurological event. Elevated ICP was treated by aggressive medical management and diversion of cerebrospinal fluid at the bedside. Removal of the PEEK implant as a treatment modality for raised intracranial pressure was not performed because it was felt the nature of edema was global, involving both supratentorial and infratentorial spaces. Furthermore, removal of the PEEK implant ran the risk of causing an upward herniation and leading to further neurological decline.
CONCLUSIONS This is the fifth reported case of combined supratentorial and infratentorial hemorrhagic infarctions after cranioplasty. Although this complication is extremely rare, the concepts of vessel injury, venous stasis, and reperfusion into dysfunctional cerebral tissue after cranioplasty should be considered when evaluating the risk of this procedure. REFERENCES 1. Bostrom S, Bobinski L, Zsigmond P, et al. Improved brain protection at decompressive craniectomy—a new method using Palacos R-40 (methylmethacrylate). Acta Neurochir. 2005;147: 279–281. 2. Britt RH, Hamilton RD. Large decompressive craniectomy in the treatment of acute subdural hematoma. Neurosurgery. 1978;2: 195–200. 3. Chibbaro S, Tacconi L. Role of decompressive craniectomy in the management of severe head injury with refractory cerebral edema and intractable intracranial pressure. Our experience with 48 cases. Surg Neurol. 2007;68:632–638. 4. Chibarro S, Fricia M, Valee F, et al. The impact of early cranioplasty on cerebral blood flow and metabolism and its correlation with neurological and cognitive outcome: prospective multi-center study on 34 patients. Indian J Neurosurg. 2012;1: 17–22. 5. Yamaura A, Sato M, Meguro K, et al. Cranioplasty following decompressive craniectomy—analysis of 300 cases (author’s transl). No Shinkei Geka. 1977;5:345–353. 6. Isago T, Nozaki M, Kikuchi Y, et al. Sinking flap syndrome: a case of improved cerebral blood flow after cranioplasty. Ann Plast Surg. 2004;3:288–292. 7. Sakamoto S, Eguchi K, Kiura Y, et al. CT perfusion imaging in the syndrome of the sinking flap before and after cranioplasty. Clin Neurol Neurosurg. 2006;108:583–585. 8. Chang V, Hartzfeld P, Langlois M, et al. Outcomes of cranial repair after craniectomy. J Neurosurg. 2010;112:1120–1124. 9. Rangel-Castilla L, Gasco J, Nauta HJW, et al. Cerebral pressure autoregulation in traumatic brain injury. Neurosurg Focus. 2008; 25:E7.
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10. Sobani ZA, Shamim MS, Zafar SN, et al. Cranioplasty after decompressive craniectomy: an institutional audit and analysis of factors related to complications. Surg Neurol Int. 2011;2:123. 11. Stephens FL, Mossop CM, Bell RS, et al. Cranioplasty complications following wartime decompressive craniectomy. Neurosurg Focus. 2010;28:E3. 12. Gooch MR, Gin GE, Kenning TJ, et al. Complications of cranioplasty following decompressive craniectomy: analysis of 62 cases. Neurosurg Focus. 2009;26:E9. 13. Chitale R, Tjoumakaris S, Gonzalez F, et al. Infratentorial and supratentorial strokes after a cranioplasty. Neurologist. 20113;19:17–21. 14. Honeybul S. Sudden death following cranioplasty: a complication of decompressive craniectomy for head injury. Br J Neurosurg. 2011;25:343–345. 15. Eom KS, Kim DW, Kang SD. Bilateral diffuse intracerebral hemorrhagic infarction after cranioplasty with autologous bone graft. Clin Neurol Neurosurg. 2010;112:336–340. 16. Vavilala MS, Lee LA, Boddu K, et al. Cerebral autoregulation in pediatric traumatic brain injury. Pediatr Crit Care Med. 2004;5: 257–263. 17. Harper AM. Autoregulation of cerebral blood flow: influence of the arterial blood pressure on the blood flow through the cerebral cortex. J Neurol Neurosurg Psychiatry. 1966;29:398–403. 18. Kontos HA, Wei EP, Navari RM, et al. Responses of cerebral arteries and arterioles to acute hypotension and hypertension. Am J Physiol. 1978;234:H371–H383. 19. Lassen NA. Cerebral blood flow and oxygen consumption in man. Physiol Rev. 1959;39:183–238. 20. Lassen NA. Autoregulation of cerebral blood flow. Circ Res. 1964;15:201–204. 21. Bouma GJ, Muizelaar JP, Bandoh K, et al. Blood pressure and intracranial pressure-volume dynamics in severe head injury: relationship with cerebral blood flow. J Neurosurg. 1992;77:15–19. 22. Steiner LA, Czosnyka M, Piechnik SK, et al. Continuous monitoring of cerebrovascular pressure reactivity allows determination of optimal cerebral perfusion pressure in patients with traumatic brain injury. Crit Care Med. 2002;30:733–738. 23. Simard JM, Bellefleur M. Systemic arterial hypertension in head trauma. Am J Cardiol. 1989;63:32C–35C. 24. Junger EC, Newell DW, Grant GA, et al. Cerebral autoregulation following minor head injury. J Neurosurg. 1997;86:425–432. 25. Sahuquillo J, Munar F, Baguena M, et al. Evaluation of cerebrovascular CO2 reactivity and autoregulation in patients with post-traumatic diffuse brain swelling (diffuse injury III). Acta Neurochir Suppl. 1998;71:233–236. 26. Bouma GJ, Muizelaar JP, Fatouros P. Pathogenesis of traumatic brain swelling: role of cerebral blood volume. Acta Neurochir Suppl. 1998;71:272–275. 27. Stoyka WW, Schutz H. The cerebral response to sodium nitroprusside and trimethaphan controlled hypotension. Can Anaesth Soc J. 1975;22:275–283. 28. Vavilala MS, Muangman S, Waitayawinyu P, et al. Neurointensive care: impaired cerebral autoregulation in infants and young children early after inflicted traumatic brain injury: a preliminary report. J Neurotrauma. 2007;24:87–96.
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139
Acute Global Ischemic Stroke After Cranioplasty Case Report and Review of the Literature Erwin Mangubat, MD and Sepehr Sani, MD
Introduction: Cranioplasty procedures are performed usually after devastating neurological injuries requiring craniectomies. Although relatively safe, global intracerebral infarction is a poorly understood, and most often, lethal complication after cranioplasty. We report here one such case with a thorough literature review with insight as to possible etiologies of this injury. Case Report: A 14-year-old girl underwent a left-sided decompressive hemicraniectomy for treatment of a subdural hematoma and cerebral edema. The patient’s neurological condition eventually improved and she presented for cranioplasty repair of the defect 83 days after her initial operation. Six hours after an uneventful procedure, the patient’s neurological examination declined. Immediate CT scan revealed global edema. Despite all treatment measures, the patient progressed to global ischemia and brain death and expired. Conclusions: Although global intracerebral infarction after cranioplasty is extremely rare, the concepts of vessel injury, venous stasis, and reperfusion into dysfunctional cerebral tissue after cranioplasty should be considered when evaluating the risk of this procedure. Key Words: cranioplasty, complications, stroke, global ischemia
(The Neurologist 2015;19:135–139)
A
n increasing number of cranioplasty procedures are performed in neurosurgical practice mainly for cosmetic and protective purposes. Neurological improvement has been reported, possibly attributed to improvements in cerebral blood flow and metabolism after such a procedure.1–5 Particularly in cases of sinking flap syndrome (a phenomenon of paradoxical herniation that is theoretically a result from a mismatch of atmospheric pressure and forces of gravity being greater than intracranial pressure), cranioplasty has been attributed with further neurological improvement through increased bilateral hemispheric cerebral blood flow.6,7 However, complications after cranioplasty are not uncommon. Infection, wound dehiscence, intracerebral hemorrhage, hygroma, subgaleal collections, bone resorption, break-through seizures, neurological deficits, and hydrocephalus have been reported in 16% to 34% of studied patients.8–12 Global intracerebral infarction after cranioplasty is a rare devastating complication that is poorly understood, of which there are only 4 other reported cases to date.13,14 We report here the case of a 14-year-old girl with left-sided traumatic brain injury who developed bilateral supratentorial and From the Department of Neurosurgery, Rush University Medical Center, Chicago, IL. The authors declare no conflict of interest. Reprints: Sepehr Sani, MD, Department of Neurosurgery, Rush University Medical Center, 1725 West Harrison Street, Suite 855, Chicago, IL 60612. E-mail: [email protected]. Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 1074-7931/15/1905-0135 DOI: 10.1097/NRL.0000000000000024
The Neurologist
Volume 19, Number 5, May 2015
infratentorial hemorrhagic strokes with rapid progression to brain death. An extensive literature review and discussion regarding possible etiologies are provided.
CASE REPORT A 14-year-old girl who was a victim of pedestrian versus motor vehicle accident with an initial Glasgow coma scale (GCS) of 5 underwent a left-sided decompressive hemicraniectomy for treatment of a subdural hematoma and cerebral edema (Fig. 1A). The patient’s neurological condition eventually improved to GCS 9 and she presented for cranioplasty repair of the defect 83 days after her initial operation. The patient’s preoperative CT scan revealed encephalomalacia in the left posterior temporooccipital region and a paradoxical midline shift from left-to-right measuring 1.9 cm (Fig. 1B). A custom synthetic porous PEEK (polyether ether ketone) implant was implanted uneventfully. Postoperatively, the patient was noted to be at neurological baseline and CT revealed reexpansion of the left hemisphere associated with a parafalcine subdural hematoma and numerous petechial subcortical intracranial hemorrhages (Figs. 2A, B). Six hours later, the patient’s neurological examination declined and began to develop hypotension requiring intravenous pressors. Immediate CT obtained (Figs. 2C, D) revealed diffuse supratentorial and infratentorial cerebral edema with effacement of sulci, basal cisterns, gray-white junction, and increasing lateral and third ventricular sizes. CT angiography (CTA) of the head revealed diffuse narrowing in the vessels of the anterior and posterior circulation, likely reflecting attenuation due to diffuse cerebral edema. CTA of the neck demonstrated an intimal flap with focal out-pouching in the distal cervical portion of the right internal carotid artery, which was not flow limiting and was stable as compared with a CTA done at the time of initial trauma (Fig. 3). CT venogram of the head demonstrated a filling defect in the left sigmoid sinus and distal aspect of left transverse sinus (Fig. 4), as well as poor opacification in the superior sagittal sinus likely related to sluggish flow. Because of worsening ventriculomegaly, the ventricular peritoneal shunt was externalized at the bedside and converted into an external ventricular drain with opening pressure >20 cm H2O. Despite continuous cerebrospinal fluid drainage, intracranial pressure remained >50 mm Hg. Follow-up CT scan 10 hours postoperatively (Figs. 2E, F) revealed diffuse hypodensities and hemorrhagic foci in bilateral hemispheres and brainstem. The patient shortly thereafter progressed to brain death and expired.
DISCUSSION Acute global hemorrhagic ischemia is a rare but devastating complication after cranioplasty. Review of 4 cases13–15 previously reported along with the presented report suggests a phenomenology that begins immediately in the postoperative period with a malignant and rapid course leading to diffuse and irreversible edema and brain death (Table 1). Previous heroic attempts at performing bilateral supratentorial and infratentorial craniectomies have proven futile, suggesting that the underlying mechanism is ischemic in origin rather than neurogenic or vasogenic edema. www.theneurologist.org |
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
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FIGURE 1. Noncontrasted CT head (A) demonstrates a left subdural hematoma with diffuse cerebral edema immediately after the patient’s traumatic injury. Three-month status postoperative left hemicraniectomy noncontrasted CT head (B) demonstrates an associated paradoxical midline shift to the right.
There are a number of proposed mechanisms that may have resulted in this devastating complication: (1) hypotensive event, (2) intraoperative vascular insufficiency, (3) venous stasis, (4) a “hyperperfusion congestion,” and (5) dysautonomia. The clearest explanation for this catastrophic event could be as a result of severe hypotension, leading to a severe anoxic brain injury with massive cerebral edema. Although anesthesia records did not show evidence of perioperative systemic hypotension, the patient did suffer a brief period of hypotension requiring vasopressors several hours after surgery. However, this is unlikely the causative event, as demonstrated on the immediate postoperative CT scan, there had already been signs of reexpansion and cerebral edema. In addition, even prolonged hypotensive episodes more often result in classic watershed infarcts rather than immediate global cerebral edema. Intraoperative vascular insufficiency may have also been a factor caused by positional stenosis or dissection of vessels related to positioning in the operating room. The patient did suffer a right-sided cervical internal carotid artery dissection upon her initial injury. However, CTA evidence demonstrated a non–flow-limiting stable lesion. Moreover, the patient did not have evidence of vertebral artery injury that would explain the posterior circulation ischemia. In addition, positioning for the patient was done in a manner such to limit the need to turn her head to no more than 20 degrees during surgery. As described by Chitale et al,13 deep venous occlusion can lead to diffuse cerebral edema, infarcts, and hemorrhagic conversion resulting in a similar clinical picture. The CT venogram in our patient did show some slowing of the left transverse sinus venous sinus, but no definitive occlusion or thrombosis. Moreover, this unilateral transverse sinus finding
136 | www.theneurologist.org
is unlikely sufficient to account for the global ischemia suffered by this patient and may be rather an anomaly as a result of the associated massive cerebral edema. Another possible causal mechanism may be associated with reexpansion of intracerebral tissue in the presence of a chronically dysfunctional brain related to impaired cerebral autoregulation, impaired tissue compliance from shuntdependent hydrocephalus, and sunken flap syndrome. This may have lead to a “hyperperfusion congestion”-like syndrome that could have caused global cerebral ischemia, resulting in multiple areas of petechial hemorrhage, in turn, leading to secondary neurogenic edema, herniation, and death. Following cranioplasty in patients with sunken flap syndrome, increased global cerebral blood flow has been demonstrated in a number of diagnostic tools, such as transcranial Doppler ultrasonography, xenon CT, and dynamic CT perfusion.6,10 This increase in cerebral perfusion, which in many patients would be associated with neurological improvement, may be detrimental in those patients with severe cases of cerebral autoregulation impairment.16 Cerebral blood flow autoregulation describes the complex intrinsic ability of the brain to maintain a stable cerebral blood flow by constantly changing cerebral vascular resistance despite fluctuations in arterial blood pressure and cerebral perfusion pressure.17–20 In the acutely injured brain, cerebral autoregulation may be dysfunctional, leading to episodes of hypoperfusion or hyperemia.21,22 Sudden increases in mean arterial blood pressure can be more easily transmitted into the microcirculation and can contribute to either areas of infarction or secondary hemorrhages and edema.23 In adults, the incidence of impaired cerebral autoregulation is 28% after moderate and 67% after severe traumatic brain injury.24,25 In the
Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
The Neurologist
Volume 19, Number 5, May 2015
Global Stroke After Cranioplasty
FIGURE 2. Immediate postoperative left cranioplasty noncontrasted CT head demonstrates reexpansion of the left hemisphere associated with parafalcine subdural hematoma (A) and subcortical petechial hemorrhages (B). C and D, Six hours status postcranioplasty noncontrasted CT head demonstrates diffuse supratentorial and infratentorial cerebral edema with effacement of the sulci, basal cisterns, loss of gray-white junction, and increased bilateral and third ventricular sizes. E and F, Ten hours postoperative follow-up CT scan demonstrates diffuse hypodensities and hemorrhagic foci in bilateral hemispheres and brainstem.
pediatric population, impaired cerebral autoregulation has been found in 17% after mild and 42% after severe traumatic brain injury.26,27 Furthermore, the degree of impairment in children Copyright
r
may be worse as compared with that in adults. Vavilala et al28 observed that adolescents have a slightly delayed return of cerebral blood flow in response to transient hypotension.
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FIGURE 3. CT angiography of the neck immediately status post the patient’s initial traumatic injury demonstrates a non–flow-limiting carotid dissection (A), which is stable as compared with the CT angiography done status postcranioplasty (B). Arrows indicate area of dissection.
As Chitale et al13 described, a theoretical chain of events would begin with reequilibration of brain pressure vectors by removal of atmospheric pressure vector that would result in brain reexpansion after cranioplasty coupled with perfusion increases. Such movement may result in the stretch of
FIGURE 4. CT venogram of the head demonstrates a filling defect in the left sigmoid sinus and distal aspect of the left transverse sinus (arrow).
138 | www.theneurologist.org
supratentorial, infratentorial, and perforator intracranial vessels, resulting in a transient decrease in perfusion and microvascular injury, increasing the propensity for hemorrhage. Eom et al15 propose that the rapid increase in bilateral cerebral blood flow and volume in a chronic dysfunctional brain may result in venous stasis and congestion that can lead to thrombosis and diffuse hemorrhagic infarcts. Reexpansion may lead to compression of PCA vessels on the incisura, leading to large territory infarctions. In addition, this increase in cerebral perfusion may have increased the risk of hemorrhage into already weak brain tissue with impaired autoregulation. Furthermore, such a rapid reexpansion could have involved areas such as the hypothalamus that may cause dysautonomia, leading to changes in cerebral perfusion pressure. Therefore, for those who have suffered a severe head injury necessitating a hemicraniectomy, it may be useful to understand a patient’s cerebral autoregulatory capability before undergoing cranioplasty, particularly in those patients with sunken flap syndrome and/or hydrocephalus where tissue compliance is in question. Unfortunately there are no goldstandard methods to assess cerebral autoregulation. One modality currently used in clinical practice to assess cerebral autoregulation is pressure reactivity index (PRx) monitoring, which is defined as the correlation coefficient between slow waves in ICP and arterial blood pressure. PRx describes cerebral vasoreactivity and the level of disturbance in physiological vascular responses to changes in mean arterial blood pressure.9 Although such data obtained may not necessarily
Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
The Neurologist
Volume 19, Number 5, May 2015
Global Stroke After Cranioplasty
TABLE 1. Reported Cases of Global Cerebral Ischemia After Cranioplasty
Age/Sex
Cause/Site of Initial Injury
Paradoxical Cerebral Herniation
Shunt Dependent Hydrocephalus
Timing of Cranioplasty (d)
1
22/M
Trauma/bifrontal
N/A
Yes
88
Autologous Death
2 3 1
16/M 16/M 64/M
Trauma/bifrontal Trauma/bifrontal CVA/right
N/A N/A Yes
Yes Yes No
70 80 1y
Autologous Death Autologous Death PEEK Death
1
14/F
Trauma/left
Yes
Yes
83
References Number Honeybul et al14 Chitale et al13 This study
Type of Implant
PEEK
Result
Death
CVA indicates cerebrovascular accident; F, female; M, male; PEEK, polyether ether ketone.
change surgical management, it would at the very least provide insight to which patients are at risk of suffering such a catastrophic neurological event. Elevated ICP was treated by aggressive medical management and diversion of cerebrospinal fluid at the bedside. Removal of the PEEK implant as a treatment modality for raised intracranial pressure was not performed because it was felt the nature of edema was global, involving both supratentorial and infratentorial spaces. Furthermore, removal of the PEEK implant ran the risk of causing an upward herniation and leading to further neurological decline.
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