The use of mild hypothermia for patients with severe vasospasm: a preliminary report

Health Care Expenditures Associated with Delayed Cerebral Ischemia Following Subarachnoid Hemorrhage: A Propensity-Adjusted Analysis

OBJECTIVE

The additional hospital costs associated with delayed cerebral ischemia (DCI) have not been well investigated in prior literature. In this study, the total hospital cost of DCI in aneurysmal subarachnoid hemmorhage (aSAH) patients treated at a single quaternary center was analyzed.

METHODS

All patients in the Post-Barrow Ruptured Aneurysm Trial treated for an aSAH between January 1, 2014, and July 31, 2019, were retrospectively analyzed. DCI was defined as cerebral infarction identified on computed tomography, magnetic resonance imaging, or autopsy after exclusion of procedure-related infarctions. The primary outcome was the difference in total cost (including hospital, discharge facility, and all follow-up) using a propensity-adjusted analysis. Propensity score covariate-adjusted linear regression analysis included age, sex, open versus endovascular treatment, Hunt and Hess score, and Charlson Comorbidity Index score.

RESULTS

Of the 391 patients included, 144 (37%) had DCI. Patients with DCI had a significantly greater cost compared to patients without DCI (mean standard deviation $112,081 [$54,022] vs. $86,159 [$38,817]; P < 0.001) and a significantly greater length of stay (21 days [11] vs. 18 days [8], P = 0.003, respectively). In propensity-adjusted linear regression analysis, both DCI (odds ratio, $13,871; 95% confidence interval, $7558-$20,185; P < 0.001) and length of stay (odds ratio, $3815 per day; 95% confidence interval, $3480-$4149 per day; P < 0.001) were found to significantly increase the cost.

CONCLUSIONS

The significantly higher costs associated with DCI further support the evidence that adverse effects associated with DCI in aSAH pose a significant burden to the health care system.

Therapeutic hypothermia protocols

The application of targeted temperature management has become common practice in the neurocritical care setting. It is important to recognize the pathophysiologic mechanisms by which temperature control impacts acute neurologic injury, as well as the clinical limitations to its application. Nonetheless, when utilizing temperature modulation, an organized approach is required in order to avoid complications and minimize side-effects. The most common clinically relevant complications are related to the impact of cooling on hemodynamics and electrolytes. In both instances, the rate of complications is often related to the depth and rate of cooling or rewarming. Shivering is the most common side-effect of hypothermia and is best managed by adequate monitoring and stepwise administration of medications specifically targeting the shivering response. Due to the impact cooling can have upon pharmacokinetics of commonly used sedatives and analgesics, there can be significant delays in the return of the neurologic examination. As a result, early prognostication posthypothermia should be avoided.

Management of delayed cerebral ischemia after subarachnoid hemorrhage

For patients who survive the initial bleeding event of a ruptured brain aneurysm, delayed cerebral ischemia (DCI) is one of the most important causes of mortality and poor neurological outcome. New insights in the last decade have led to an important paradigm shift in the understanding of DCI pathogenesis. Large-vessel cerebral vasospasm has been challenged as the sole causal mechanism; new hypotheses now focus on the early brain injury, microcirculatory dysfunction, impaired autoregulation, and spreading depolarization. Prevention of DCI primarily relies on nimodipine administration and optimization of blood volume and cardiac performance. Neurological monitoring is essential for early DCI detection and intervention. Serial clinical examination combined with intermittent transcranial Doppler ultrasonography and CT angiography (with or without perfusion) is the most commonly used monitoring paradigm, and usually suffices in good grade patients. By contrast, poor grade patients (WFNS grades 4 and 5) require more advanced monitoring because stupor and coma reduce sensitivity to the effects of ischemia. Greater reliance on CT perfusion imaging, continuous electroencephalography, and invasive brain multimodality monitoring are potential strategies to improve situational awareness as it relates to detecting DCI. Pharmacologically-induced hypertension combined with volume is the established first-line therapy for DCI; a good clinical response with reversal of the presenting deficit occurs in 70 % of patients. Medically refractory DCI, defined as failure to respond adequately to these measures, should trigger step-wise escalation of rescue therapy. Level 1 rescue therapy consists of cardiac output optimization, hemoglobin optimization, and endovascular intervention, including angioplasty and intra-arterial vasodilator infusion. In highly refractory cases, level 2 rescue therapies are also considered, none of which have been validated. This review provides an overview of current state-of-the-art care for DCI management.

The use of targeted temperature management for elevated intracranial pressure

The use of hypothermia for treatment of intracranial hypertension is controversial, despite no other medical therapy demonstrating consistent improvements in morbidity or mortality. Much of this may be the result of negative results from randomized controlled trials. However, the patients selected for these trials may have obscured the results in the populations most likely to benefit. Further, brain injury does not behave uniformly, not even within a diagnosis. Therefore, therapies may have more benefit in some diseases, less in others. This review focuses on the effect on outcome of intracranial hypertension in common disease processes in the neurocritical care unit, and identifies who is most likely to benefit from the use of hypothermia.

Vascular KCNQ (Kv7) potassium channels as common signaling intermediates and therapeutic targets in cerebral vasospasm

Cerebral vasospasm after subarachnoid hemorrhage (SAH) is characterized by prolonged severe constriction of the basilar artery, which often leads to ischemic brain damage. Locally elevated concentrations of spasmogenic substances induce persistent depolarization of myocytes in the basilar artery, leading to continuous influx of calcium (Ca) through voltage-sensitive Ca channels and myocyte contraction. Potassium (K) channel openers may have therapeutic utility to oppose membrane depolarization, dilate the arteries, and reduce ischemia. Here, we examined the involvement of vascular Kv7 K channels in the pathogenesis of cerebral vasospasm and tested whether Kv7 channel openers are effective therapeutic agents in a rat model of SAH. Patch-clamp experiments revealed that 3 different spasmogens (serotonin, endothelin, and vasopressin) suppressed Kv7 currents and depolarized freshly isolated rat basilar artery myocytes. These effects were significantly reduced in the presence of a Kv7 channel opener, retigabine. Retigabine (10 μM) also significantly blocked L-type Ca channels, reducing peak inward currents by >50%. In the presence of a selective Kv7 channel blocker, XE991, the spasmogens did not produce additive constriction responses measured using pressure myography. Kv7 channel openers (retigabine or celecoxib) significantly attenuated basilar artery spasm in rats with experimentally induced SAH. In conclusion, we identify Kv7 channels as common targets of vasoconstrictor spasmogens and as candidates for therapeutic intervention for cerebral vasospasm.

Shivering management during therapeutic temperature modulation: nurses' perspective

Therapeutic temperature modulation, which incorporates mild hypothermia and maintenance of normothermia, is being used to manage patients resuscitated after cardiac arrest. Methods of modulating temperature include intravenous infusion of cold fluids and surface or endovascular cooling. During this therapy, the shiver response is activated as a defense mechanism in response to an altered set-point temperature and causes metabolic and hemodynamic stress for patients. Recognition of shivering according to objective and subjective assessments is vital for early detection of the condition. Once shivering is detected, treatment is imperative to avoid deleterious effects. The Bedside Shivering Assessment Scale can be used to determine the efficacy of interventions intended to blunt thermoregulatory defenses and can provide continual evaluation of patients' responses to the interventions. Nurses' knowledge and understanding of the harmful effects of shivering are important to effect care and prevent injury associated with uncontrolled shivering.

Induced hypothermia for trauma: current research and practice

Induction of hypothermia with the goal of providing therapeutic benefit has been accepted for use in the clinical setting of adult cardiac arrest and neonatal hypoxic-ischemic encephalopathy (HIE). However, its potential as a treatment in trauma is not as well defined. This review discusses potential benefits and complications of induced hypothermia (IH) with emphasis on the current state of knowledge and practice in various types of trauma. There is excellent preclinical research showing that in cases of penetrating trauma with cardiac arrest, inducing hypothermia to 10 degrees C using cardiopulmonary bypass (CPB) could possibly save those otherwise likely to die without causing neurologic sequelae. A human trial of this intervention is about to get underway. Preclinical studies suggest that inducing hypothermia may be useful to delay cardiac arrest in penetrating trauma victims who are hypotensive. There is potential for IH to be used in cases of blunt trauma, but it has not been well studied. In the case of traumatic brain injury (TBI), clinical trials have shown conflicting results, despite almost uniform efficacy seen in preclinical experiments. Major studies are analyzed and ways to standardize its use and optimize future clinical trials are discussed. More preclinical and clinical research is needed to better define whether there could be a role for IH in the case of spinal cord injuries.

Mild hypothermia (33 degrees C) reduces intracranial hypertension and improves functional outcome after subarachnoid hemorrhage in rats

OBJECTIVE

After a subarachnoid hemorrhage (SAH), the primary cause of mortality is secondary brain injury occurring within the first 48 hours after the initial bleeding. Because of the unknown pathophysiology of these early events, therapeutic approaches are scarce. Because mild hypothermia (33 degrees C) is among the strongest neuroprotectants known so far, the aim of this study was to investigate acute and delayed effects of hypothermia if applied after SAH.

METHODS

Male Sprague-Dawley rats were subjected to SAH and randomly assigned to the following groups: 1) SAH under normothermia, 2) SAH followed by 2 hours of hypothermia starting 1 hour after the bleeding, and 3) SAH followed by 2 hours of hypothermia starting 3 hours after the bleeding. Cerebral blood flow and intracranial pressure were continuously measured up to 6 hours after SAH. Mortality, neurological deficits, and body weight were assessed from postoperative day 1 to day 7. Brain water content and morphological brain damage were quantified 24 hours and 7 days after SAH, respectively.

RESULTS

Mild hypothermia reduced intracranial pressure (P < 0.001) and posthemorrhagic neurological deficits (P < 0.05) and improved postoperative weight gain significantly (P < 0.05). Mortality, cerebral blood flow, and the formation of cerebral edema were not significantly influenced by mild hypothermia.

CONCLUSION

The current results show that mild hypothermia (33 degrees C) exhibits sustained neuroprotection if applied up to 3 hours after SAH. Overall, mild hypothermia seems to be an effective neuroprotective strategy after SAH and should therefore be evaluated as a treatment option for SAH in patients.

[Therapeutic hypothermia in neurocritical patients]

Induced hypothermia in neurocritical patients is one of the most promising neuroprotective therapies in the last decade. Unfortunately, the promising results obtained in experimental studies have had an unequal reflection in the different diseases that affect the neurocritical patient. The use of therapeutic hypothermia is clearly established in patients with neurological deterioration after cardiac arrest. On the contrary, its use in patients with traumatic brain injury is highly controversial. There is not enough evidence in stroke and hemorrhagic patients to support its use except in clinical trials. Nowadays, the greater understanding of the pathophysiology of secondary brain damage, the go od clinical results obtained in randomized clinical trials in patients with cerebral anoxia after ventricular fibrillation and the new cooling methods that have appeared have improved the interest of hypothermia in neurocritical patients. Induced hypothermia has a role in the intensive care unit. Critical care physicians should be familiar with the physiologic effects, current indications, techniques, and complications of induced hypothermia. This review elaborates on the clinical implications of hypothermia research in traumatic brain injury, anoxic, brain injury, stroke and intracerebral hemorrhage.

THERAPEUTIC HYPOTHERMIA IN PATIENTS WITH ANEURYSMAL SUBARACHNOID HEMORRHAGE, REFRACTORY INTRACRANIAL HYPERTENSION, OR CEREBRAL VASOSPASM

OBJECTIVE

To evaluate the feasibility and safety of mild hypothermia treatment in patients with aneurysmal subarachnoid hemorrhage (SAH) who are experiencing intracranial hypertension and/or cerebral vasospasm (CVS).

METHODS

Of 441 consecutive patients with SAH, 100 developed elevated intracranial pressure and/or symptomatic CVS refractory to conventional treatment. Hypothermia (33–34°C) was induced and maintained until intracranial pressure normalized, CVS resolved, or severe side effects occurred.

RESULTS

Thirteen patients were treated with hypothermia alone, and 87 were treated with hypothermia in combination with barbiturate coma. Sixty-six patients experienced poor-grade SAH (Hunt and Hess Grades IV and V) and 92 had Fisher Grade 3 and 4 bleedings. The mean duration of hypothermia was 169 ± 104 hours, with a maximum of 16.4 days. The outcome after 1 year was evaluated in 90 of 100 patients. Thirty-two patients (35.6%) survived with good functional outcome (Glasgow Outcome Scale [GOS] score, 4 and 5), 14 (15.5%) were severely disabled (GOS score, 3), 1 (1.1%) was in a vegetative state (GOS score, 2), and 43 (47.8%) died (GOS score, 1). The most frequent side effects were electrolyte disorders (77%), pneumonia (52%), thrombocytopenia (47%), and septic shock syndrome (40%). Of 93 patients with severe side effects, 6 (6.5%) died as a result of respiratory or multi-organ failure.

CONCLUSION

Prolonged systemic hypothermia may be considered as a last-resort option for a carefully selected group of SAH patients with intracranial hypertension or CVS resistant to conventional treatment. However, complications associated with hypothermia require elaborate protocols in general intensive care unit management.

Temperature management in acute neurologic disorders

Temperature management in acute neurologic disorders has received considerable attention in the last 2 decades. Numerous trials of hypothermia have been performed in patients with head injury, stroke, and cardiac arrest. This article reviews the physiology of thermoregulation and mechanisms responsible for hyperpyrexia. Detrimental effects of fever and benefits of normalizing elevated temperature in experimental models are discussed. This article presents a detailed analysis of trials of induced hypothermia in patients with acute neurologic insults and describes methods of fever control.

Induced hypothermia and fever control for prevention and treatment of neurological injuries

Increasing evidence suggests that induction of mild hypothermia (32-35 degrees C) in the first hours after an ischaemic event can prevent or mitigate permanent injuries. This effect has been shown most clearly for postanoxic brain injury, but could also apply to other organs such as the heart and kidneys. Hypothermia has also been used as a treatment for traumatic brain injury, stroke, hepatic encephalopathy, myocardial infarction, and other indications. Hypothermia is a highly promising treatment in neurocritical care; thus, physicians caring for patients with neurological injuries, both in and outside the intensive care unit, are likely to be confronted with questions about temperature management more frequently. This Review discusses the available evidence for use of controlled hypothermia, and also deals with fever control. Besides discussing the evidence, the aim is to provide information to help guide treatments more effectively with regard to timing, depth, duration, and effective management of side-effects. In particular, the rate of rewarming seems to be an important factor in establishing successful use of hypothermia in the treatment of neurological injuries.

Use of induced hypothermia for neuroprotection: indications and application

Therapeutic temperature regulation has become an exciting field of interest. Mild-to-moderate hypothermia is a safe and feasible management strategy for neuroprotection and control of intracranial pressure in neurological catastrophies such as traumatic brain injury, subarachnoid and intracerebral hemorrhage, and large hemispheric stroke. Fever is associated with worse neurological outcome in patients with brain injury, normothermia may be of benefit in this patient population. The efficacy of mild-to-moderate hypothermia has been proven for neuroprotection after cardiac arrest with ventricular fibrillation as initial rhythm, and after neonatal asphyxia. Application of hypothermia and fever control in neurocritical care, available cooling technologies and systemic effects and complications of hypothermia will be discussed.

[Therapeutic hypothermia in the intensive care unit]

Experimental studies have demonstrated the neuroprotective effects of induced hypothermia in prevention of secondary insults following acute brain injury. Therefore, therapeutic hypothermia could be effective in the clinical setting of intensive care therapy. In this paper pathophysiological aspects of induced hypothermia are discussed and clinically relevant study results of hypothermia therapy are given in respect to evidence-based medicine.

Therapeutic temperature modulation in neurocritical care

The ability to effectively achieve and maintain long-term temperature control is an important goal that has been previously unachievable in the neurocritical care setting. Previous attempts have been limited by the inability to overcome physiologic defense mechanisms, short duration of action, or significant adverse effects. Recent advances in technology have made therapeutic temperature modulation feasible. In this review, current concepts of therapeutic temperature modulation are presented. New advances in technology may provide an important breakthrough in the ability to reduce fever-associated morbidity in neurocritically ill patients. What remains to be seen is whether the advantages of these technologies will outweigh the risks associated with therapeutic temperature modulation.

Temperature Management in Acute Neurologic Disorders

Temperature management in acute neurologic disorders has received considerable attention in the last 2 decades. Numerous trials of hypothermia have been performed in patients with head injury, stroke, and cardiac arrest. This article reviews the physiology of thermoregulation and mechanisms responsible for hyperpyrexia. Detrimental effects of fever and benefits of normalizing elevated temperature in experimental models are discussed. This article presents a detailed analysis of trails of induced hypothermia in patients with acute neurologic insults and describes methods of fever control.

Controversies in the management of aneurysmal subarachnoid hemorrhage*

BACKGROUND

The care of patients with aneurysmal subarachnoid hemorrhage has evolved significantly with the advent of new diagnostic and therapeutic modalities. Although it is believed that these advances have contributed to improved outcomes, considerable uncertainty persists regarding key areas of management.

OBJECTIVE

To review selected controversies in the management of aneurysmal subarachnoid hemorrhage, with a special emphasis on endovascular vs. surgical techniques for securing aneurysms, the diagnosis and therapy of cerebral vasospasm, neuroprotection, antithrombotic and anticonvulsant agents, cerebral salt wasting, and myocardial dysfunction, and to suggest venues for further clinical investigation.

DATA SOURCE

Search of MEDLINE and Cochrane databases and manual review of article bibliographies.

DATA SYNTHESIS AND CONCLUSIONS

Many aspects of care in patients with aneurysmal subarachnoid hemorrhage remain highly controversial and warrant further resolution with hypothesis-driven clinical or translational research. It is anticipated that the rigorous evaluation and implementation of such data will provide a basis for improvements in short- and long-term outcomes.

Cerebral vasospasm: results of a structured multimodal treatment

Symptomatic cerebral vasospasm (CVS) with delayed ischemic neurologic deficits affects about one third of the patients after aneurysmal subarachnoid hemorrhage (SAH). In spite of the lack of definite evidence of large clinical trials, the devastating outcome of the natural history of symptomatic CVS demands an aggressive CVS treatment in a practically oriented, structured multimodal treatment regimen. With our treatment protocol good functional outcome could be reached in 66% of the patients with symptomatic CVS. This policy requires close and fast multidisciplinary collaboration between neurosurgeons, neuroradiologists, competent in endovascular interventions, and specialists for neurointensive care. We report on our experience with 79 cases with symptomatic CVS and delayed ischemic neurologic deficit (DIND) after aneurysmal SAH. The different treatment options with CVS are reviewed and practical guidelines for a step by step treatment are given.

[Controlled mild-to-moderate hypothermia in the intensive care unit]

Controlled hypothermia is used as a therapeutic intervention to provide neuroprotection and (more recently) cardioprotection. The growing insight into the underlying pathophysiology of apoptosis and destructive processes at the cellular level, and the mechanisms underlying the protective effects of hypothermia, have led to improved application and to a widening of the range of potential indications. In many centres hypothermia has now become part of the standard therapy for post-anoxic coma in certain patients, but for other indications its use still remains controversial. The negative findings of some studies may be partly explained by inadequate protocols for the application of hypothermia and insufficient attention to the prevention of potential side effects. This review deals with some of the concepts underlying hypothermia-associated neuroprotection and cardioprotection, and discusses some potential clinical indications as well as reasons why some clinical trials may have produced conflicting results. Practical aspects such as methods to induce hypothermia, as well as the side effects of cooling are also discussed.

Is hypothermia a stress condition in HepG2 cells?

To understand hypothermia as a stress condition we determined the expression and localization of Hsp70 under hyperthermic and hypothermic stress in human hepatoma HepG2 cells. Western blot analysis indicates that there was a statistically significant increase of Hsp70 expression under thermal stresses. Immunohistochemically, the distribution of inducible Hsp70 in stressed cells showed a granular pattern mostly in the cytoplasm. At subcellular level, Hsp70 was localized in the nucleus, vacuoles, cytoskeletal components and dispersed throughout the cytoplasm. Accumulation of Hsp70 in cells under hypothermia could be related to restitution of cell equilibrium modified by this thermal stress condition. The protective effect of hypothermia could be associated with promotion of Hsp expression. We suggest that hypothermia is a stress capable of inducing Hsp70 expression in human HepG2 cells.

Therapeutische Hypothermie nach Sch�del-Hirn-Trauma oder Subarachnoidalblutung

BACKGROUND

We aimed to explore current practices in use of therapeutic hypothermia after traumatic brain injury (TBI) or subarachnoid hemorrhage (SAH) in intensive care of adults.

METHODS

Questionnaires were sent to anaesthesia department chairs in German hospitals with neurosurgical care in January 2004 with a survey focussing on cooling procedures, temperature measurement, depth and duration of hypothermia, and rewarming after therapy.

RESULTS

99 (67%) questionnaires on TBI and 95 (64%) on SAH could be analysed. Hypothermia was used in 39% after TBI and 18% after SAH. Its aims were neuroprotection in approximately 45% and control of refractory intracranial hypertension in approximately 50%. However, in most cases (69% TBI, 59% SAH) hypothermia was used in less than a quarter of patients treated. A criterion for hypothermia was severe disease in approximately 40% and refractory intracranial hypertension in approximately 50%. Temperatures were targeted to 36-34 degrees C in 77% after TBI and 88% after SAH. In more than 80%, bladder temperatures were measured. For induction of hypothermia, surface cooling was applied in approximately 90%. The duration of hypothermia was 24-48 h in 62% after TBI and 29% after SAH. Cooling was orientated at the intracranial pressure (ICP) in 31% after TBI and 47% after SAH, and was used for more than 48 h in approximately 25%. After hypothermia was stopped, a rewarming rate of 0.5 degrees C/h was applied in 38% after TBI and 53% after SAH. In approximately 35%, rewarming was orientated at the ICP, and in 33% after TBI and 24% after SAH, it was performed over 24 h. After SAH, spontaneous rewarming was used in 24%.

CONCLUSION

Therapeutic hypothermia is used in 39% after TBI and 18% after SAH in the intensive care of German anaesthesia departments. There is no standard in management, and there is wide variation in practices of duration of cooling and rewarming. For patients' benefit, evidence-based recommendations on therapeutic hypothermia should be published by the appropriate medical societies in the German language.

Novel applications of therapeutic hypothermia: report of three cases

Therapeutic hypothermia can provide neuroprotection in various situations where global or focal neurological injury has occurred. Hypothermia has been shown to be effective in a large number of animal experiments. In clinical trials, hypothermia has been used in patients with postanoxic injury following cardiopulmonary resuscitation, in traumatic brain injury with high intracranial pressure, in the perioperative setting during various surgical procedures and for various other indications. There is thus evidence that hypothermia can be effective in various situations of neurological injury, although a number of questions remain unanswered. We describe three patients with unusual causes of neurological injury, whose clinical situation was in fundamental aspects analogous to conditions where hypothermia has been shown to be effective.

Application of therapeutic hypothermia in the ICU: opportunities and pitfalls of a promising treatment modality. Part 1: Indications and evidence

OBJECTIVE

Hypothermia has been used for medicinal purposes since ancient times. This paper reviews the current potential clinical applications for mild hypothermia (32-35 degrees C).

DESIGN AND SETTING

Induced hypothermia is used mostly to prevent or attenuate neurological injury, and has been used to provide neuroprotection in traumatic brain injury, cardiopulmonary resuscitation, stroke, and various other disorders. The evidence for each of these applications is discussed, and the mechanisms underlying potential neuroprotective effects are reviewed. Some of this evidence comes from animal models, and a brief overview of these models and their limitations is included in this review.

RESULTS

The duration of cooling and speed of re-warming appear to be key factors in determining whether hypothermia will be effective in preventing or mitigating neurological injury. Some other potential usages of hypothermia, such as its use in the peri-operative setting and its application to mitigate cardiac injury following ischemia and reperfusion, are also discussed.

CONCLUSIONS

Although induced hypothermia appears to be a highly promising treatment, it should be emphasized that it is associated with a number of potentially serious side effects, which may negate some or all of its potential benefits. Prevention and/or early treatment of these complications are the key to successful use of hypothermia in clinical practice. These side effects, as well as various physiological changes induced by cooling, are discussed in a separate review.

Triple-H therapy in the management of aneurysmal subarachnoid haemorrhage

Cerebral vasospasm is a recognised but poorly understood complication for many patients who have aneurysmal subarachnoid haemorrhage and can lead to delayed ischaemic neurological deficit (stroke). Morbidity and mortality rates for vasospasm are high despite improvements in management. Since the middle of the 1970s, much has been written about the treatment of cerebral vasospasm. Hypervolaemia, hypertension, and haemodilution (triple-H) therapy in an intensive-care setting has been shown in some studies to improve outcome and is an accepted means of treatment, although a randomised controlled trial has never been undertaken. In this review, the rationale for this approach will be discussed, alongside new thoughts and future prospects for the management of this complex disorder.