The following three diseases do not fall into any category. They are related, however, by the fact that each is extremely amenable to the treatment offered by a neuro-ICU. Without such therapy the outcome for these disorders can be poor. A neuro-ICU is specialized to treat:
» Neuroleptic Malignant syndrome
» Vasculitis of the Central Nervous System
What is eclampsia?
Eclampsia is a condition caused by pregnancy. The initial manifestations of this illness are called pre-eclampsia. Pre-eclampsia arises at about the 20th week of pregnancy and is characterized by hypertension (high blood pressure), edema (tissue swelling due to the movement of fluid out of blood vessels), and proteinuria (an excessive accumulation of protein in the urine). When a pre-eclamptic patient develops neurologic symptoms, the condition is referred to as eclampsia. Eclampsia is usually characterized by seizures, but can also present as blindness, visual hallucinations, or even coma. The main cause of these symptoms is hypertensive encephalopathy and cerebral edema.
Who is afflicted with eclampsia?
Eclampsia is a rare condition. About 6-8% of pregnancies are complicated by pre-eclampsia. This number rises up to 30% in twin pregnancies. Woman who are most at risk are those who are malnourished and who have never borne children. Eclampsia is one of the major causes of death and disability in pregnant women.
How is eclampsia treated in a neuro-ICU?
Treatment of eclampsia has three objectives:
- Control of hypertension. Anti-hypertensive agents are administered for this purpose. The most commonly used drugs are labetolol, nicardipine, and nitroprusside.
- Management of seizures. Magnesium sulfate is highly effective for the treatment of seizures which arise as a result of eclampsia. Thus magnesium sulfate remains a standard therapy for the treatment of eclampsia. Seizures can also be controlled by anticonvulsant drugs such as diazepam and phenytoin.
- Treatment of cerebral edema. It is common for the increased blood pressure associated with pre-eclampsia to cause leakage of fluid from the blood vessels supplying the brain. Under these circumstances the brain can become swollen with fluid, a condition known as cerebral edema. Cerebral edema can give rise to a dangerous increase in the pressure within the skull (intracranial pressure or ICP). Cerebral edema is treated with: (a) hyperventilation, which causes the blood to become overly alkaline and results in the constriction of blood vessels supplying the brain. Since less blood is perfusing the brain cerebral edema, and thus ICP, is reduced; and (b) mannitol treatment, which osmotically draws fluid out of brain tissue and back into blood vessels, thus reducing cerebral edema and lowering ICP.
NEUROLEPTIC MALIGNANT SYNDROME
NMS is a rare disease which is induced by the use of neuroleptic drugs. It is estimated that only 0.2% of those treated with neuroleptic medication will develop NMS. Neuroleptics are a class of drugs used to treat psychiatric disorders. Clinically this disease manifests itself in four ways:
- Hyperthermia: Patients with NMS have a high fever which is drug-induced. About 40% of patients have a temperature above 104 degrees F and fever can reach as high as 108 degrees F. Hyperthermia occurs because neuroleptics affect those portions of the brain which are responsible for regulating body temperature down.
- Muscle rigidity: Generalized muscle rigidity occurs in all patients with NMS. Individuals often have muscle tremors as well as myoclonus (shock-like contractions of a group of muscles). In addition, muscle rigidity can be manifested as trouble swallowing (dysphagia), excess secretion of saliva (sialorrhea), difficulty performing voluntary movements (dyskinesia), and uncontrolled rotation of the eyeball (oculogyric crisis).
- Altered mental status: Victims of NMS suffer from clouding of consciousness. Consciousness can be altered to the point of stupor (an impairment of consciousness in which only continual stimulation can arouse the patient), or even to the point of coma. In addition, patients afflicted with NMS are often delirious, meaning that they are confused, disoriented, and agitated
- Autonomic dysfunction: Patients with NMS commonly experience disorders of the autonomic nervous system. This is manifested as rapid heart rate (tachycardia), high blood pressure (hypertension), and rapid breathing (tachypnea).
What complications are associated with NMS?
The high fever and muscle rigidity associated with NMS can give rise to the following complications: metabolic acidosis (increased acidity of the blood); respiratory failure, which results from rigidity of the chest muscles and diaphragm; muscle breakdown (rhadbomyolysis); and renal failure, which can result from myoglobinuria. If these complications are uncontrolled, NMS can be fatal.
How is NMS treated in a neuro-ICU?
Neuroleptic malignant syndrome, although rare, is extremely amenable to treatment in a neuro-ICU. Such treatment vastly improves the prognosis of patients with NMS. Therapy involves:
- The immediate discontinuation of all neuroleptic drugs and/or drugs affecting the brain's levels of dopamine.
- Pharmacotherapy with two drugs specialized to treat this condition: dantrolene and bromocriptine. Both of these agents serve to decrease muscle rigidity. Dantrolene is rarely used in most medical centers, and familiarity with its use can lead to more effective treatment.
- Aggressive temperature reduction is accomplished with cooling blankets.
- Intravenous fluid replacement.
- Proper breathing is ensured by intubation with a breathing tube, and placement of the patient on a mechanical ventilator.
VASCULITIS OF THE CENTRAL NERVOUS SYSTEM
Vasculitis (or angiitis) refers to inflammation of a blood vessel. Primary CNS Vasculitis results from an auto-immune attack on the blood vessels supplying the brain and spinal cord. Such inflammation results in the blockage of these vessels, and thus stops the flow of blood to parts of the brain or spinal cord. Cessation of blood flow to an area of tissue is known as ischemia. The result of vasculitis is that both the blood vessel wall and the tissue that blood vessel supplies will die.
What causes CNS vasculitis?
The underlying cause of CNS vasculitis is poorly understood. However, it is widely accepted that an autoimmune mechanism is responsible for the disease. When the body detects foreign pathogens it directs antibodies against them. These antibodies bind to the foreign organisms (or antigens) and form antigen-antibody complexes. During the development of CNS vasculitis these complexes are deposited in the walls of certain blood vessels supplying the brain and spinal cord. This deposition results in the release of chemicals which attract defensive white blood cells to the vessel wall. These white cells infiltrate the vessel wall, ingest the antigen-antibody complexes, and release enzymes which damage the vessel wall. The end result is the inflammation and death of the blood vessel, and the death secondarily of the tissue that the vessel no longer supplies.
What symptoms are associated with CNS vasculitis?
The symptoms associated with CNS vasculitis are varied. However, many patients with this disorder follow a similar clinical course. Patients usually develop headaches as an initial symptom. This may be accompanied by changes in the patients mental status. These symptoms are then followed by weakness over parts of the body, seizures, ataxia (an inability to smoothly coordinate muscle movements), or even coma. In fact, it is not uncommon for a patient to exhibit the signs of a stroke.
How is CNS vasculitis diagnosed?
Vasculitis which is limited to the central nervous system is rare and the diagnosis of this disease is difficult. The following techniques are employed to help establish a diagnosis:
- Measurement of the erythrocyte sedimentation rate, which is nonspecific but indicative of an ongoing inflammatory process.
- Detection of inflammation in the cerebrospinal fluid (CSF). This is performed by a lumbar puncture (or spinal tap). A needle is inserted into the small of the back to recover CSF, which circulates around the spinal cord. Levels of protein are elevated in 85% of patients with CNS vasculitis.
- Magnetic Resonance Imaging (MRI) almost always detects evidence of widespread small vessel infarcts, or unusual patterns of enhancements resulting from inflammation and breakdown of the blood-brain barrier.
- Cerebral angiography, which is an x-ray examination of blood vessels supplying the brain after the patient has been injected with a dye. This test may demonstrate irregularities of the cerebral arteries, known as "beading."
- Even with the use of these measures, a definitive diagnosis of CNS vasculitis cannot be established without a brain biopsy. This procedure involves removing a small piece of the brain for examination under a microscope. This is the only way to definitively ascertain a diagnosis of CNS vasculitis. The other methods are used as supportive evidence.
How is CNS vasculitis treated in a neuro-ICU?
A neuro-ICU is specialized to treat critically-ill neurologic patients, including patients with severe CNS vasculitis. Patients with severe depression of level of consciousness (stupor or coma) may require intubation and placement on a respirator. The administration of corticosteroids such as dexamethasone can improve the condition of patients with this disorder. Patients with severe brain swelling or increased intracranial pressure may require placement of an ICP monitor. Other treatments to reduce the auto-immune attack on the blood vessels of the brain may include plasmapheresis (removal of proteins including antibodies from the bloodstream), and immunosuppression with drugs such as cyclophosphamide. Because the suppression of the immune system can result in a number of side effects the patient's overall medical status is carefully monitored by the intensive care unit.
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August 27, 2014