Neurology Critical Care
Neurological Intensive Care is one of the newest and fastest–growing specialties in medicine today. Currently, there are approximately 25 academic neuro–ICUs in North America. Neuro–ICUs uniquely bring together specially trained physicians and nurses armed with advanced technology. Mayo Clinic researchers perform clinical and basic science research on patients in a critical care setting to gain better understanding of their critical illnesses and to develop improved and innovative treatments for these conditions.
Advanced monitoring techniques used in neuro–ICUs allow the identification of critical problems before permanent neurologic injury occurs. A neuro–ICU also provides many specialized therapeutic options for patients with serious neurologic illness. Management of patients in a neuro–ICU is essential to achieve a favorable outcome.
Alejandro Rabinstein, M.D., is a member of METRIC (Multidisciplinary Epidemiology and Translational Research in Intensive Care), a group that studies the epidemiology, pathophysiology and management of specific critical care syndromes such as acute lung injury, sepsis and shock. In collaboration with the Thoracic Disease Research Unit, Anesthesia Clinical Research Unit, Division of Transfusion Medicine, Department of Anesthesiology, Department of Health Sciences Research and several national and international partners (University of California San Francisco, ARDS–network, International Study of Mechanical Ventilation, University of Amsterdam) METRIC researchers have been working on several projects related to the prevention and treatment of acute lung injury/acute respiratory distress syndrome (ALI/ARDS), and in particular its iatrogenic causes (ventilator associated lung injury–VALI, transfusion related lung injury–TRALI). Additional projects in which Dr. Rabinstein is engaged include studying the influence of:
- ICU structure: Staffing and housestaff education
- ICU processes:
- Criteria for determining safety for discharging patients from ICU
- Evidence based practices of sedation, invasive and noninvasive mechanical ventilation, blood product transfusion and sepsis
- ICU Outcomes: Performance of individual ICUs based on benchmarks derived from severity prognostic models
Cognitive Recovery Following Symptomatic Ischemic Stroke (ProCog)
This study aims to map the natural recovery of stroke by investigating people who have had an ischemic stroke and those who have not. Stroke must have occurred within the last 30 days. The study is funded by the Hanley Development Award. Participants have two neuropsychological evaluations at 30 and 90 days post–stroke to evaluate speech, language, memory, attention and visual spatial skills. The knowledge gained from this study will be used to develop treatment trials and enhance rehabilitation.
Cognitive Recovery of Intracerebral Hemorrhage and Ischemic Stroke
Similar in study design to ProCog, this project is funded by Brooks Rehabilitation, and seeks to evaluate cognitive recovery from both hemorrhagic and ischemic stroke. It is a collaborative effort between Brooks and Mayo Clinic.
Surgical Trial in Lobar Intracerebral Hemorrhage (STICH–II)
This is a randomized clinical trial that compares the efficacy of either no surgery or surgical treatment of intracerebral hemorrhage. The study is funded and directed by investigators at Newcastle University in the UK. The value of surgery in this situation is unproven and the decision of whether or not to surgically evacuate an intracerebral hematoma is made currently without the benefit of quality data from a randomized clinical trial. This study is anticipated to facilitate the development of guidelines of safety and efficacy of surgical evacuation versus conservative non–surgical treament. Eligible patients are enrolled within 48 hours of their stroke and, if randomized to the surgical group, have surgery within 60 hours of stroke onset.
M. Allison Cato Jackson, M.D., of Nemours Clinic in Jacksonville is involved in a study comparing people who have had an ischemic stroke to evaluate how the brain compensates after a stroke. Patients perform different tasks (finger tapping, repeating words, generating words on their own: such as name an animal you would find in a zoo) while in the fMRI scanner. These tasks are repeated several times while collecting data on cerebral blood flow; by so doing, the parts of the brain that are active (have higher blood flow) while doing those tasks is mapped. The extent of brain activation determined by blood flow differences is measured to evaluate how the brain that may be compensating for the injury by activating areas of the brain not normally activated in the healthy control individuals.
Weaning From a Mechanical Ventilator in Patients With Guillain–Barre Syndrome (GBS)
R.D. Henderson, M.D., and colleagues retrospectively reviewed 114 patients with Guillain–Barre Syndrome (GBS) who required mechanical ventilation to elucidate risk factors for prolonged weaning in this population. By dividing patients into three subgroups, those requiring mechanical ventilation for less than three weeks; those requiring prolonged ventilation but having a short weaning time; and those requiring prolonged ventilation and prolonged weaning, they determined that a bedside vital capacity (VC) above 12 mL/kg was predictive of a successful weaning. Age over 60 years and the presence of preexisting lung disease also predicted a longer weaning period. They concluded that patients under 60 years without preexisting lung disease can probably be weaned within two weeks if they have a VC above 15 mL when weaning commences. The team underscored the importance of respiratory muscle strength testing. (Neurology, 2000;54(suppl 3):A246. Abstract S44.004.)
Eelco F.M. Wijdicks, M.D., studied brain edema after cardiac surgery – an uncommon and often asymptomatic condition. Dr. Wijdicks and his colleagues studied a 34–year–old man who had postoperative left flaccid hemiplegia and anosognosia after undergoing cardiac surgery. MRI scans showed evidence of brain edema predominantly in the right hemisphere. The patient’s symptoms resolved within three days, and there was no evidence of cerebral infarction. While the cause for the unilateral brain edema is unknown, the patient’s clinical course and imaging are supportive for hyperperfusion syndrome wherein the brain could not compensate for increased perfusion pressure that follows a period of reduced perfusion. This resulted in a temporary encephalopathy that mimicked a stroke. (Annals of Thoracic Surgery, 2008 Aug;86(2):634–7.)
Coma Rating Scale
Dr. Wijdiks was a member of a research team that developed and subsequently validated the use of "Full Outline of Unresponsiveness" (FOUR) rating scale. Initially, the performance and validity of this scale was validated in the Neurosciences Intensive Care Unit. Their recent study was designed to validate the use of FOUR score in the emergency department (ED) using non–neurology staff. The team also compared its performance to the standard rating scale for this purpose, the Glasgow Coma Scale (GCS), and correlated the score to functional outcome at hospital discharge and to survival from coma. They found that the FOUR score can be reliably used in the ED by non–neurology staff. The neurologic detail incorporated in the FOUR score makes it more useful in management and triage of patients. (Neurocritical Care, 2008 Sep 20.)
Aspergillus Brain Infection
Drs. Alejandro, Rabinstein and Wijdicks studied two patients with insidious Aspergillus sinusitis leading to catastrophic CNS infection in investigating cerebral aspergillosis, an important cause of mortality in organ transplant recipients that is typically associated with concomitant pulmonary infection. From this research, they concluded that sinusitis may be an early sign of aspergillosis and may present with new onset headache. Untreated, it can be followed by symptoms of chronic meningitis and ischemic or hemorrhagic stroke. Aspergillus species have an affinity for invading blood vessels and spreading along the internal elastic lamina of these vessels, inducing vasculitis and thrombosis. Fungal cultures of CSF often remain negative. The sensitivity of this test in immunocompromised patients has been reported up to 90% but is decreased by antifungal therapy. A prospective multicenter study on the diagnostic value of galactomannan in patients with cerebral aspergillosis is needed. Their findings indicate that, in cases of cerebral aspergillosis, galactomannan antigen may be detected in CSF when serum indexes are normal. (Neurology, 2008 Jun 10;70(24 Pt 2):2411–3.)
The Value of Surgery for Intracerebral Hematoma
Drs. Rabinstein, Wijdicks and Atkinson from Mayo Clinic’s Department of Neurosurgery investigated supratentorial intracerebral hematomas, which are often evacuated in rapidly deteriorating patients. Surgery may prevent death, but not necessarily disability. They studied the outcome of emergent clot evacuation in patients with worsening massive intracerebral hemorrhage. They concluded that craniotomy for rapidly worsening patients with supratentorial intracerebral hemorrhage and radiologic signs of brain tissue shift may result in functional independence in a quarter of patients. However, all comatose patients who lost upper brainstem reflexes and had extensor posturing died despite surgery. (Neurology, 2002 May 14;58(9):1367–72.) As noted above, a STICH–II prospective randomized clinical trial to address the value of this surgery is now ongoing at Mayo Clinic.
Delayed Cerebral Ischemis Post Subarachnoic Hemorrhage
Drs. Rabinstein, Atkinson and Wijdicks analyzed the distribution patterns of delayed cerebral ischemia after subarachnoid hemorrhage (SAH) and the factors that determine their occurrence. They concluded that the two most common patterns of delayed cerebral ischemia after aneurysmal SAH are single cortical infarction, typically near the ruptured aneurysm, and multiple widespread lesions including subcortical locations, often unrelated to the site of aneurysm rupture. These two patterns may represent different pathophysiological mechanisms or different degrees of severity of the same vascular process. (Stroke, 2005 May;36(5):992–7. Epub 2005 Apr 14.)
Neurocritical care research highlights
Over the past decade, Mayo Clinic has forged advancements in the area of neurology critical care for its patients. Working together, our clinicians and researchers have:
- Developed national criteria for defining brain death
- Developed predictors of acute neuromuscular respiratory failure in Guillian–Barré syndrome
- Developed extubation criteria for acutely ill neurologic patients
- Characterized natriuretic factors in aneurysmal subarachnoid hemorrhage
- Characterized neurologic complications after transplant
- Developed predictors of deterioration in neurologic critical illness
- Characterized CT scan abnormalities predicting ischemia–related cerebral swelling
- Provided early surgical evacuation of lobar hematoma in patients whose condition is deteriorating
- Assessed cerebral metabolism using magnetic resonance technology in critical neurologic illness
- Refined pulmonary care in acutely ill neurologic patients
Our goals for the future include investigations of the implication of abnormal volume and sodium homeostasis in aneurysmal subarachnoid hemorrhage; and treatment of early swelling in large hemispheric stroke using an invasive cooling device.
In addition, there are numerous other ongoing research projects that will continue to advance our care of critically ill patients in the area of neurology.