- Meeting abstract
- Open Access
Hypothermia after aneurysmal subarachnoid hemorrhage
Critical Care volume 16, Article number: A16 (2012)
Aneurysmal subarachnoid hemorrhage (SAH) is a common and frequently devastating condition, accounting for 1 to 7% of all strokes with an incidence of 9.1 per 100,000 . Major advances in SAH management over the past three decades have decreased case fatality by 0.8% per year, but it is still 40% and many survivors have long-term disabilities . The most important and potentially treatable complication is development of delayed cerebral ischemia (DCI), which can progress to cerebral infarction associated with poor outcome.
The pathogenesis of DCI is multifactorial and assumed to be initiated in the early phase of SAH . The onset of SAH is characterized by a short-lasting and cerebral perfusion pressure (CPP)-dependent decrease in cerebral blood flow (CBF) leading to global cerebral ischemia . Elevated intracranial pressure (ICP) and acute cerebral ischemia are the main factors for early disruption of the blood-brain barrier as well as impairment of autoregulation associated with brain edema and brain swelling. Important pathogenic mechanisms of CPP-independent hypoperfusion include acute vasoconstriction, cortical spreading ischemia, and activation of the inflammatory response. The release of oxyhemoglobin and endothelin-1 (ET-1) are the key factors for cortical spreading ischemia, reduced nitric oxide (NO) availability, and secondary cytotoxic edema formation. Cerebral vasospasm (CVS) is a delayed morphological narrowing of cerebral arteries, occurring 4 to 10 days after SAH. Although CVS have been associated with DCI, it is generally accepted that CVS is not solely responsible for DCI . In fact, DCI may occur in the absence of CVS and vice versa and the distribution of CVS may fail to reliably predict the subsequent pattern of cerebral infarction .
Neuroprotective strategies to prevent DCI have been mainly focused on treatment of CVS, but despite extensive research, effective and/or causative prophylaxis and treatment are not available . So far, oral nimodipine is the only drug that can reduce the incidence of DCI and poor outcome, but there is no beneficial effect on CVS . Hypothermia (HT) treatment exerting numerous protective effects such as a decrease in cerebral metabolism , stabilization of the blood-brain barrier , reduction of cerebral edema , suppression of excitatory neurotransmitter concentrations  and inflammatory reactions  seems to be well suited as a neuroprotective strategy. In the following, the clinical application of HT after SAH is presented by reviewing the existing literature.
Hypothermia during aneurysm surgery
In the past, promising studies on intraoperative HT during aneurysm surgery as an attempt to reduce ischemic injury have been published [14–18]. The Intraoperative Hypothermia for Aneurysm Surgery Trial (IHAST) applied HT in a randomized study in 1,001 patients with good-grade SAH (WFNS 1 to 3); however, it found no improvement in neurological outcome 3 months after surgery . Post-hoc analysis demonstrated no difference in the incidence of cognitive impairment between hypothermic and normothermic groups . Furthermore, there was no evidence for the benefit of intraoperative HT on 24-hour and 3-month outcome in patients who underwent temporary clipping . It has to be noted that these results only apply to good-grade SAH patients and may not be extrapolated to the general SAH population. This suggests that only a carefully selected subgroup of patients, with specific complications induced by SAH, may benefit from HT treatment at a particular time and for certain duration.
Hypothermia in patients with poor-grade subarachnoid hemorrhage
Several experimental studies have demonstrated that HT is effective in minimizing neuronal damage, if induced before or early after the SAH. Kawamura and colleagues found a reduced expression of c-jun and hsp-70 mRNA, indicating a reduced stress response that may otherwise manifest as necrosis or apoptosis . Thome and colleagues and Schubert and colleagues demonstrated that early induction of HT, up to 60 minutes after SAH, reversed CPP-independent hypoperfusion and brain edema formation, preserved cerebral autoregulation, and reduced accumulation of lactate and glutamate [11, 12, 23]. On the other hand, delayed induction of HT, up to 180 minutes after SAH, failed to reduce brain edema formation, thus indicating a limited time window of HT application . However, HT was effective in reducing ICP and associated with improved neurological recovery. These studies encourage early induction of HT in poor-grade SAH patients, for example, as soon as signs of brain swelling are seen on CT scans.
So far, only few retrospective case series have investigated the effect of mild HT during the acute phase of SAH. Table 1 presents an overview of these studies applying HT within 24 hours after SAH to patients with poor-grade SAH (WFNS 4 to 5). The duration of HT varied between 2 and 14 days. Overall outcome results were unsatisfactory with a mortality rate of 47.4% and favorable outcome in less than one-quarter of cases. Yasui and colleagues evaluated seven patients admitted within 6 hours from symptom onset and treated with HT for 48 hours . PET studies during HT revealed a reduction in cerebral oxygen metabolism exceeding the decrease in CBF, thus indicating a state of luxury perfusion. However, according to the Barthel Index only two patients were independent, one was partially dependent, able to walk without assistance, and more than one-half of the patients bedridden at 12 months after SAH. Anei and colleagues compared outcome results before and after introduction of HT treatment to their institution and found no significant difference in the mortality rate with 56.3% and 57.9%, respectively . The authors noted that post-HT fever can be a serious complication resulting in brain swelling and unfavorable outcome. In contrast to these studies, Gasser and colleagues showed more promising outcome results in 21 patients with poor-grade SAH (WFNS 4 to 5) and induction of HT after developing intracranial hypertension (>15 mmHg) that was refractory to conventional treatment. HT was induced on average 4.2 ± 3.3 days after SAH and maintained for 4.3 ± 3.9 days. Prolonged HT (>72 hours) was associated with an increased risk of systemic complications, but 10 patients (47.6%) showed favorable outcome (GOS 4 to 5) and five patients died (23.8%).
Hypothermia in patients with delayed cerebral ischemia/cerebral vasospasm
Recently, a SAH-CVS model in dogs demonstrated that HT can attenuate the degree of CVS up to 14 days after SAH, possibly by regulating the levels of ET-1 and NO . The duration of HT was directly proportional to the duration of relieving CVS. Table 2 presents an overview of clinical studies applying HT to patients with symptomatic CVS leading to DCI. Nagao and colleagues treated five patients with good-grade SAH (H&H I to III), starting HT either during delayed aneurysm clipping or if CVS was refractory to hyperdynamic and endovascular therapy . Four patients survived with favorable outcome and one patient was severely disabled. In a follow-up study, Nagao and colleagues included eight patients with good-grade SAH (H&H II to III), and seven patients had favorable outcome and one survived severely disabled . According to SPECT studies, HT was associated with decreased CBF levels in all patients. Nakamura and colleagues reported a reduction in arterio-jugular oxygen difference (AVDO2) during HT in five patients (H&H III to IV), thus indicating a reduced metabolic demand . All patients received hyperdynamic therapy before and during HT, but outcome results were unsatisfactory. Possible contributing factors of poor outcome include a higher grade of SAH and it is unclear whether endovascular treatment was applied or not. In our series of 100 SAH patients treated with HT, 28 patients had symptomatic CVS refractory to hypertensive therapy and endovascular treatment . HT was combined with barbiturate coma in 23 of 28 patients and maintained until CVS resolved or severe side effects occurred (mean duration 5.7 ± 3.3 days). Although the majority of patients had poor-grade SAH (H&H 4 to 5 in 57.1%, Fisher 3 to 4 in 85.7%), favorable outcome (GOS 4 to 5) was achieved in 57.1%. In patients with intracranial hypertension (>20 mmHg) with and without refractory CVS, favorable outcome was obtained in only 25.0% and 26.5%, respectively. Systemic side effects possibly caused from HT and/or barbiturate coma included pneumonia in 52.0%, thrombocytopenia (<100,000/µl) in 47.0%, septic shock syndrome in 40.0%, and acute respiratory distress syndrome in 16.0%. In a subgroup of seven patients with combined HT and barbiturate coma, daily levels of IL-6, IL-1β, TNFα, and leukocyte count in the cerebrospinal fluid and plasma were quantified . IL-6 levels in the cerebrospinal fluid and systemic IL-1β levels were significantly lower compared with patients receiving barbiturate coma alone (n = 8), thus indicating HT-related attenuation of the inflammatory response.
So far, the evidence of HT on improved outcome after SAH is limited. Intraoperative HT has been abandoned based on the randomized Intraoperative Hypothermia Study on Aneurysm Surgery in good-grade SAH patients. The available data suggest that HT may improve outcome in a carefully selected subgroup of patients developing intracranial hypertension and/or symptomatic CVS that are refractory to conventional treatment. Further evaluation of cerebral hemodynamics and oxygenation during HT treatment is required to obtain important insights in the effects of HT and to identify patients who may benefit most.
Feigin VL, Lawes CM, Bennett DA, Anderson CS: Stroke epidemiology: a review of population-based studies of incidence, prevalence, and case-fatality in the late 20th century. Lancet Neurol 2003, 2: 43-53. 10.1016/S1474-4422(03)00266-7
Nieuwkamp DJ, Setz LE, Algra A, Linn FH, de Rooij NK, Rinkel GJ: Changes in case fatality of aneurysmal subarachnoid haemorrhage over time, according to age, sex, and region: a meta-analysis. Lancet Neurol 2009, 8: 635-642. 10.1016/S1474-4422(09)70126-7
Ostrowski RP, Colohan AR, Zhang JH: Molecular mechanisms of early brain injury after subarachnoid hemorrhage. Neurol Res 2006, 28: 399-414. 10.1179/016164106X115008
Bederson JB, Germano IM, Guarino L: Cortical blood flow and cerebral perfusion pressure in a new noncraniotomy model of subarachnoid hemorrhage in the rat. Stroke 1995, 26: 1086-1091. discussion 1091-1092 10.1161/01.STR.26.6.1086
Vergouwen MD, Ilodigwe D, Macdonald RL: Cerebral infarction after subarachnoid hemorrhage contributes to poor outcome by vasospasm-dependent and -independent effects. Stroke 2011, 42: 924-929. 10.1161/STROKEAHA.110.597914
Rabinstein AA, Weigand S, Atkinson JL, Wijdicks EF: Patterns of cerebral infarction in aneurysmal subarachnoid hemorrhage. Stroke 2005, 36: 992-997. 10.1161/01.STR.0000163090.59350.5a
Muroi C, Seule M, Mishima K, Keller E: Novel treatments for vasospasm after subarachnoid hemorrhage. Curr Opin Crit Care 2012, 18: 119-126. 10.1097/MCC.0b013e32835075ae
Castanares-Zapatero D, Hantson P: Pharmacological treatment of delayed cerebral ischemia and vasospasm in subarachnoid hemorrhage. Ann Intensive Care 2011, 1: 12. 10.1186/2110-5820-1-12
Erecinska M, Thoresen M, Silver IA: Effects of hypothermia on energy metabolism in mammalian central nervous system. J Cereb Blood Flow Metab 2003, 23: 513-530.
Karibe H, Zarow GJ, Graham SH, Weinstein PR: Mild intraischemic hypothermia reduces postischemic hyperperfusion, delayed postischemic hypoperfusion, blood-brain barrier disruption, brain edema, and neuronal damage volume after temporary focal cerebral ischemia in rats. J Cereb Blood Flow Metab 1994, 14: 620-627. 10.1038/jcbfm.1994.77
Schubert GA, Poli S, Schilling L, Heiland S, Thome C: Hypothermia reduces cytotoxic edema and metabolic alterations during the acute phase of massive SAH: a diffusion-weighted imaging and spectroscopy study in rats. J Neurotrauma 2008, 25: 841-852. 10.1089/neu.2007.0443
Schubert GA, Poli S, Mendelowitsch A, Schilling L, Thome C: Hypothermia reduces early hypoperfusion and metabolic alterations during the acute phase of massive subarachnoid hemorrhage: a laser-Doppler-flowmetry and microdialysis study in rats. J Neurotrauma 2008, 25: 539-548. 10.1089/neu.2007.0500
Muroi C, Frei K, El Beltagy M, Cesnulis E, Yonekawa Y, Keller E: Combined therapeutic hypothermia and barbiturate coma reduces interleukin-6 in the cerebrospinal fluid after aneurysmal subarachnoid hemorrhage. J Neurosurg Anesthesiol 2008, 20: 193-198. 10.1097/ANA.0b013e31817996bf
Hindman BJ, Todd MM, Gelb AW, Loftus CM, Craen RA, Schubert A, Mahla ME, Torner JC: Mild hypothermia as a protective therapy during intracranial aneurysm surgery: a randomized prospective pilot trial. Neurosurgery 1999, 44: 23-32. discussion 32-33 10.1097/00006123-199901000-00009
Karibe H, Sato K, Shimizu H, Tominaga T, Koshu K, Yoshimoto T: Intraoperative mild hypothermia ameliorates postoperative cerebral blood flow impairment in patients with aneurysmal subarachnoid hemorrhage. Neurosurgery 2000, 47: 594-599. discussion 599-601
Ogilvy CS, Carter BS, Kaplan S, Rich C, Crowell RM: Temporary vessel occlusion for aneurysm surgery: risk factors for stroke in patients protected by induced hypothermia and hypertension and intravenous mannitol administration. J Neurosurg 1996, 84: 785-791. 10.3171/jns.1996.84.5.0785
Sato K, Yoshimoto T: Systemic and cerebral haemodynamics during craniotomy under mild hypothermia in patients with acute subarachnoid haemorrhage. Acta Neurochir (Wien) 2000, 142: 1013-1019. discussion 1019-1020 10.1007/s007010070056
Kimme P, Fridrikssen S, Engdahl O, Hillman J, Vegfors M, Sjoberg F: Moderate hypothermia for 359 operations to clip cerebral aneurysms. Br J Anaesth 2004, 93: 343-347. 10.1093/bja/aeh206
Todd MM, Hindman BJ, Clarke WR, Torner JC: Mild intraoperative hypothermia during surgery for intracranial aneurysm. N Engl J Med 2005, 352: 135-145. 10.1056/NEJMoa040975
Anderson SW, Todd MM, Hindman BJ, Clarke WR, Torner JC, Tranel D, Yoo B, Weeks J, Manzel KW, Samra S: Effects of intraoperative hypothermia on neuropsychological outcomes after intracranial aneurysm surgery. Ann Neurol 2006, 60: 518-527. 10.1002/ana.21018
Hindman BJ, Bayman EO, Pfisterer WK, Torner JC, Todd MM: No association between intraoperative hypothermia or supplemental protective drug and neurologic outcomes in patients undergoing temporary clipping during cerebral aneurysm surgery: findings from the Intraoperative Hypothermia for Aneurysm Surgery Trial. Anesthesiology 2010, 112: 86-101. 10.1097/ALN.0b013e3181c5e28f
Kawamura Y, Yamada K, Masago A, Katano H, Matsumoto T, Mase M: Hypothermia modulates induction of hsp70 and c-jun mRNA in the rat brain after subarachnoid hemorrhage. J Neurotrauma 2000, 17: 243-250. 10.1089/neu.2000.17.243
Thome C, Schubert G, Piepgras A, Elste V, Schilling L, Schmiedek P: Hypothermia reduces acute vasospasm following SAH in rats. Acta Neurochir Suppl 2001, 77: 255-258.
Torok E, Klopotowski M, Trabold R, Thal SC, Plesnila N, Scholler K: Mild hypothermia (33°C) reduces intracranial hypertension and improves functional outcome after subarachnoid hemorrhage in rats. Neurosurgery 2009, 65: 352-359. discussion 359 10.1227/01.NEU.0000345632.09882.FF
Yasui N, Kawamura S, Suzuki A, Hadeishi H, Hatazawa J: Role of hypothermia in the management of severe cases of subarachnoid hemorrhage. Acta Neurochir Suppl 2002, 82: 93-98.
Anei R, Sakai H, Iihara K, Nagata I: Effectiveness of brain hypothermia treatment in patients with severe subarachnoid hemorrhage: comparisons at a single facility. Neurol Med Chir (Tokyo) 2010, 50: 879-883. 10.2176/nmc.50.879
Wang ZP, Chen HS, Wang FX: Influence of plasma and cerebrospinal fluid levels of endothelin-1 and NO in reducing cerebral vasospasm after subarachnoid hemorrhage during treatment with mild hypothermia, in a dog model. Cell Biochem Biophys 2011, 61: 137-143. 10.1007/s12013-011-9170-z
Nagao S, Irie K, Kawai N, Kunishio K, Ogawa T, Nakamura T, Okauchi M: Protective effect of mild hypothermia on symptomatic vasospasm: a preliminary report. Acta Neurochir Suppl 2000, 76: 547-550.
Nagao S, Irie K, Kawai N, Nakamura T, Kunishio K, Matsumoto Y: The use of mild hypothermia for patients with severe vasospasm: a preliminary report. J Clin Neurosci 2003, 10: 208-212. 10.1016/S0967-5868(02)00322-3
Nakamura T, Tatara N, Morisaki K, Kawakita K, Nagao S: Cerebral oxygen metabolism monitoring under hypothermia for severe subarachnoid hemorrhage: report of eight cases. Acta Neurol Scand 2002, 106: 314-318.
Seule MA, Muroi C, Mink S, Yonekawa Y, Keller E: Therapeutic hypothermia in patients with aneurysmal subarachnoid hemorrhage, refractory intracranial hypertension, or cerebral vasospasm. Neurosurgery 2009, 64: 86-92. discussion 92-93 10.1227/01.NEU.0000336312.32773.A0
About this article
Cite this article
Seule, M., Keller, E. Hypothermia after aneurysmal subarachnoid hemorrhage. Crit Care 16, A16 (2012). https://doi.org/10.1186/cc11274
- Intracranial Hypertension
- Delayed Cerebral Ischemia
- Aneurysmal Subarachnoid Hemorrhage
- Barbiturate Coma
- Brain Edema Formation