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13 Neurologic Manifestations of Systemic Disease
Karl E. Misulis, MD, PhD and E. Lee Murray, MD
CHAPTER CONTENTS
◦Hypertension with Acute Ischemic Stroke
◦Hypertension with Acute Intracranial Hemorrhage
•Posterior Reversible Encephalopathy Syndrome
◦Altered Clearance of Medications
◦Hyperosmolar Hyperglycemic State
•Electrolyte and Fluid Disorders
OVERVIEW
Presentation and differential diagnosis of acute neurologic complications of medical diseases were discussed in Chapter 11. In this chapter, we discuss selected disorders in greater detail. Other chapters discuss manifestations of systemic diseases in the context of clinically related disorders, as follows:
•Neurologic complications of cancers: Chapter 25
•Infectious diseases: Chapter 17
•Hypoxic-ischemic encephalopathy: Chapter 14
•Stroke: Chapter 16
•Hospitalization encephalopathy: Chapter 18
•Diabetic neuropathy: Chapter 28
HYPERTENSION
Hypertension has a multiplicity of neurologic implications, but in the hospital the following scenarios are of special concern:
•Hypertension with acute ischemic stroke
•Hypertension with acute intracranial hemorrhage
•Malignant hypertension/hypertensive crisis
Hypertension with Acute Ischemic Stroke
Blood pressure (BP) is commonly increased at the time of acute ischemic stroke. Implications of this include increased risk of bleeding with IV tissue plasminogen activator (tPA) if BP remains high, but also a higher baseline blood pressure prior to the stroke worsens outcome. Recent advances in BP management may be responsible for some of the improvement in stroke outcome seen independently of thrombolytic therapy.1
Decisions on BP management are governed by many factors. Guidelines from 2013 are freely available.2
Some of the most important factors governing BP management in acute stroke are:
•Elevated BP at time of presentation can be either or a combination of baseline hypertension plus reactive BP from the acute ischemia.
•Contraindication to IV tPA presently is severe uncontrolled hypertension, often defined as systolic BP of greater than 185 or diastolic of greater than 110 mm Hg.3
•Marked lowering of BP with acute stroke can worsen deficit by reducing perfusion of affected tissue.
MANAGEMENT of BP depends on the clinical scenario:
•Acute stroke that is a candidate for IV tPA but with BP too high: The goal is to bring the BP into a range that would allow IV tPA to be given yet not so low as to reduce perfusion pressure. Acute management is often with nicardipine or labetalol intravenously by titration. After administration of tPA, the BP must be continued to be controlled in the same manner.
•Acute stroke that is a candidate for endovascular therapy: Most hospital neurologists follow the BP management guidelines for IV tPA when managing the BP of a patient who is undergoing endovascular therapy.
•Acute stroke that is not a candidate for IV tPA: There is less consensus for this scenario. However, the Guidelines recommend lowering of BP by 15% during the first 24 hours after the stroke. But the antihypertensive agents should be withheld unless the systolic blood pressure is greater than 220 or the diastolic BP is greater than 120.
•Acute stroke with cerebral edema: Patients with cerebral edema following acute ischemic stroke are difficult to manage. Edema peaks at about 4 days following the acute stroke. There are less-defined guidelines, other than that marked hypertension can produce hemorrhage into the infarction, and hypotension reduces perfusion especially with cerebral edema. Antihypertensive therapy is usually minimized unless there is marked elevation. As discussed in Chapter 41, medical and, if needed, surgical management of the edema can help.
•Acute stroke has been managed, and the patient is preparing for post-hospitalization care: Details of routine BP management will not be presented here, but, as the patient is being readied for discharge or rehab, a regimen of antihypertensive therapy appropriate for outpatient therapy is established. Algorithms for routine management of BP are beyond the scope of this text, but the JNC-8 guidelines should be part of the hospital neurologist’s library.4
Hypertension with Acute Intracranial Hemorrhage
Hypertension after acute intracranial hemorrhage is common and presents a management problem since we want to lower the BP to reduce further bleeding yet do not want to reduce perfusion pressure in a patient with increased intracranial pressure (ICP). Medical and surgical management of acute intracranial hemorrhage are discussed in more detail in Chapter 16. Several studies have examined BP management in this scenario without a clear consensus. Generally, traditional management is to aim for a systolic BP of less than 180 within 6 hours from symptom onset.5 It is likely that more aggressive management will be used and guidelines will be revised.
Hypertensive Crisis
The term hypertensive crisis is predominately used, although the term malignant hypertension is widely used interchangeably. Strictly speaking, malignant hypertension includes papilledema. Both diagnoses indicate marked hypertension with organ damage involving cerebrovascular, cardiovascular, and/or renal systems.
PRESENTATION is hypertension with a complaint of headache, visual disturbance, or other neurologic or cardiac findings. Neurologic findings can include focal weakness or sensory change, confusion, or seizures.
DIAGNOSIS is suggested to the neurologist by headache or focal deficits associated with severe hypertension. Then it is confirmed by identification of other organ damage and absence of a fixed structural or vascular defect in the brain. Focal deficits due to hypertensive emergency must be distinguished from acute stroke in order to decide whether tPA should be offered. In general, rapidly fluctuating deficits favor hypertensive emergency. Neurologic symptoms that are fixed suggest infarction or hemorrhage.
•A computed tomography (CT) of the brain is performed emergently to look for bleeding or early edema.
•A magnetic resonance imaging (MRI) of the brain is ultimately performed to look for ischemia not seen on the CT.
•CT angiography (CTA) or magnetic resonance angiography (MRA) is performed at some point. MRA is generally preferable to CTA in the case of renal insufficiency, but when acute vascular event and intervention is considered, CTA may be performed emergently despite renal status.
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