Paroxysmal sympathetic hyperactivity | |
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Specialty | Neurology |
Paroxysmal sympathetic hyperactivity (PSH) is a syndrome that causes episodes of increased activity of the sympathetic nervous system. Hyperactivity of the sympathetic nervous system can manifest as increased heart rate, increased respiration, increased blood pressure, diaphoresis, and hyperthermia. [1] Previously, this syndrome has been identified as general dysautonomia but now is considered a specific form of it. It has also been referred to as paroxysmal sympathetic instability with dystonia, or PAID, and sympathetic storm. Recently, however, studies have adopted the name paroxysmal sympathetic hyperactivity to ensure specificity. [2] PSH is observed more in younger patients than older ones. It is also seen more commonly in men than women. [2] There is no known reason why this is the case, although it is suspected that pathophysiological links exist. In patients surviving traumatic brain injury, the occurrence of these episodes is one in every three. PSH can also be associated with severe anoxia, subarachnoid and intracerebral hemorrhage, and hydrocephalus. [3]
Characteristics of paroxysmal sympathetic hyperactivity include: [3]
In cases where PSH episodes develop post-injury, specifically traumatic brain injury, symptoms typically develop quickly, usually within a week. Symptom onset has been seen to average 5.9 days post-injury. [2] Episodes vary in duration and occurrence. Episodes can last as little as a few minutes or as long as ten hours, and they can occur multiple times a day. Episode duration has been seen to average 30.8 minutes and occur five to six times a day. [2] Episodes can occur naturally or arise from external triggers. Common triggers include pain or stimulation, body turning or movements, and bladder distention. Bladder distention has been observed in patients being treated in intensive care units with the concurrent use of catheters. [3] Symptoms of PSH can last from weeks to years following initial onset. As episodes persist over time, they have been found to become less frequent in occurrence but last for prolonged periods. [3]
The number of events that can lead to the development of PSH symptoms is many. The exact pathways or causes for the development of the syndrome are not known. Traumatic brain injury, hypoxia, [4] stroke, anti-NMDA receptor encephalitis (although further associations are being explored), [5] injury of the spinal cord, [1] and many other forms of brain injury can cause onset of PSH. Even more obscure diseases such as intracranial tuberculoma have been seen to cause onset of paroxysmal sympathetic hyperactivity. [6] It is observed that these injuries lead to the development of PSH or are seen in conjunction with PSH, but the pathophysiology behind these diseases and the syndrome is not well understood.
A considerable number of theories exist as to the pathophysiology:
There are many theories dealing with the pathophysiology of paroxysmal sympathetic hyperactivity. It is possible that none or multiple of these theories are correct. Research that is being conducted on PSH is focused on figuring out these pathways.
Diagnosing PSH can be very difficult due to the lack of common terminology in circulation and a lack of diagnostic criteria. [7] Different systems for diagnosis have been proposed, but a universal system has not been embraced. One example of a proposed system of diagnosis requires observation confirmation for four of the six following symptoms: fever greater than 38.3 degrees Celsius, tachycardia classified as a heart rate of 120 bpm or higher, hypertension classified as a systolic pressure higher than 160 mmHg or a pulse pressure higher than 80 mmHg, tachypnea classified as respiration rate higher than 30 breaths per minute, excess sweating, and severe dystonia. [3] Ruling out other diseases or syndromes that show similar symptoms is imperative to diagnosis as well. Sepsis, encephalitis, neuroleptic malignant syndrome, [8] malignant hyperthermia, [8] lethal catatonia, spinal cord injury (not associated with PSH), seizures, and hydrocephalus (this can be associated with PSH) are examples of diagnoses that should be considered due to the manifestation of similar symptoms before confirming a diagnosis of PSH. [3] PSH has no simple radiological features that can be observed or detected on a scan.
Various methods are used to treat PSH. Medications are used to end episodes or prevent their occurrence. Hyperbaric oxygen therapy has been explored as well. [9] Other treatments have been used, but their success is measured on a case-by-case basis. Successful treatments with qualitative results or efficacy for wider ranges of patients have not been developed.
The two most common medications used in the treatment of paroxysmal sympathetic hyperactivity are morphine sulfate and beta-blockers. [3] Morphine is useful in helping halt episodes that have started to occur. Beta-blockers are helpful in preventing the occurrence of 'sympathetic storms'. Other drugs that have been used and have in some cases been helpful are dopamine agonists, other various opiates, benzodiazepines, clonidine, and baclofen. [10] Chlorpromazine and haloperidol, both dopamine antagonists, in some cases have worsened PSH symptoms. [3] These drugs are in use currently for treatment; exact pathways are not known and wide-range helpfulness is speculative.
Morphine has been found to be effective in aborting episodes; sometimes it is the only medication that can combat the sympathetic response. Morphine helps lower respiration rates and hypertension. It is given in doses of two milligrams to eight milligrams but can be administered up to twenty milligrams. Nausea and vomiting are common side effects. Withdrawal is sometimes seen in patients. [3]
Non-selective beta-blockers are the most effective in reducing the frequency and severity of PSH episodes. They help decrease the effect of circulating catecholamines and lower metabolic rates, which are high in patients during PSH episodes. Beta-blockers also help in reducing fever, diaphoresis, and in some cases dystonia. Propranolol is a common beta-blocker administered due to the fact that it penetrates the blood-brain barrier relatively well. Typically it is administered in doses of twenty milligrams to sixty milligrams every four to six hours in the treatment of PSH. [3]
Clonidine is an alpha receptor agonist that helps reduces sympathetic activity leaving the hypothalamus and reduces circulating catecholamines. It is helpful in lowering blood pressure and heart rate, but it does not show much of an effect on other symptoms. It may also increase sympathetic inhibition in the brainstem.[ medical citation needed ] Bromocriptine is a dopamine agonist that helps lower blood pressure. Its effects are modest, but they are not well understood. Baclofen is a GABA agonist that helps control muscle spasms, proving to be helpful in treating dystonia. Benzodiazepines bind to GABA receptors and work as muscle relaxants. Benzodiazepines also combat high blood pressure and respiratory rates; however, they are associated with glaucoma, which is a rather serious side effect. Gabapentin inhibits neurotransmitter release in the dorsal horn of the spinal cord and various areas of the central nervous system. It helps treat mild symptoms and can be tolerated for longer periods of time compared to other drug treatments. Dantrolene helps combat dystonia and fever by affecting muscle contraction and relaxation cycles. It hinders the release of calcium from the sarcoplasmic reticulum, inhibiting muscle contraction. It causes decreases in respiration, but it can be very dangerous for the liver. [3] Again, these treatments are seen case by case and treat symptoms well. They do not treat the syndrome as a whole or preventatively. Efficacy varies patient to patient, as symptoms do.
Patients who develop PSH after traumatic injury have longer hospitalization and longer durations in intensive care in cases where ICU treatment is necessary. Patients often are more vulnerable to infections and spend longer times on ventilators, which can lead to an increased risk of various lung diseases. PSH does not affect mortality rate, but it increases the amount of time it takes a patient to recover from injury, compared to patients with similar injuries who do not develop PSH episodes. It often takes patients who develop PSH longer to reach similar levels of the brain activity seen in patients who do not develop PSH, although PSH patients do eventually reach these same levels. [2]
The first published case of paroxysmal sympathetic hyperactivity was Wilder Penfield's case report of a 41-year-old woman, JH, published in 1929. She had a third ventricle cholesteatoma. She displayed increased respiration, increased heart rate, diaphoresis, and increased blood pressure. She also displayed minor symptoms: pupillary dilation, hiccups, and lacrimation. At the time, her episodes were termed 'diencephalic autonomic epilepsy'. It was believed that both her sympathetic and parasympathetic nervous systems were showing overactivity. [1] The future may hold non-pharmacologic solutions such as renal sympathetic denervation. [11]
Complex regional pain syndrome (CRPS) is a form of amplified musculoskeletal pain syndrome in which pain from an physical trauma outlasts the expected recovery time. This type of AMPS must include a specific cause and often includes various visible changes, such as skin changes. Lack of these visible symptoms, or lack of an observed cause for the condition creates the diagnosis of diffuse amplified pain. Usually starting in a limb, it manifests as pain, swelling, limited range of motion, and/or changes to the skin and bones. It may initially affect one limb and then spread throughout the body; 35% of affected people report symptoms throughout their whole bodies. Two types exist: reflex sympathetic dystrophy (RSD) and causalgia. Having both types is possible.
The Fregoli delusion is a rare disorder in which a person holds a delusional belief that different people are in fact a single person who changes appearance or is in disguise. The syndrome may be related to a brain lesion and is often of a paranoid nature, with the delusional person believing themselves persecuted by the person they believe is in disguise.
Cerebral edema is excess accumulation of fluid (edema) in the intracellular or extracellular spaces of the brain. This typically causes impaired nerve function, increased pressure within the skull, and can eventually lead to direct compression of brain tissue and blood vessels. Symptoms vary based on the location and extent of edema and generally include headaches, nausea, vomiting, seizures, drowsiness, visual disturbances, dizziness, and in severe cases, coma and death.
Dysautonomia or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia has many causes, not all of which may be classified as neuropathic. A number of conditions can feature dysautonomia, such as Parkinson's disease, multiple system atrophy, dementia with Lewy bodies, Ehlers-Danlos syndromes, autoimmune autonomic ganglionopathy and autonomic neuropathy, HIV/AIDS, autonomic failure, and postural orthostatic tachycardia syndrome.
Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury (mmHg) and at rest, is normally 7–15 mmHg for a supine adult. The body has various mechanisms by which it keeps the ICP stable, with CSF pressures varying by about 1 mmHg in normal adults through shifts in production and absorption of CSF.
Dystonia is a neurological hyperkinetic movement disorder in which sustained or repetitive muscle contractions result in twisting and repetitive movements or abnormal fixed postures. The movements may resemble a tremor. Dystonia is often intensified or exacerbated by physical activity, and symptoms may progress into adjacent muscles.
In neurology, abulia, or aboulia, refers to a lack of will or initiative and can be seen as a disorder of diminished motivation (DDM). Abulia falls in the middle of the spectrum of diminished motivation, with apathy being less extreme and akinetic mutism being more extreme than abulia. The condition was originally considered to be a disorder of the will, and aboulic individuals are unable to act or make decisions independently; and their condition may range in severity from subtle to overwhelming. In the case of akinetic mutism, many patients describe that as soon as they "will" or attempt a movement, a "counter-will" or "resistance" rises up to meet them.
Closed-head injury is a type of traumatic brain injury in which the skull and dura mater remain intact. Closed-head injuries are the leading cause of death in children under 4 years old and the most common cause of physical disability and cognitive impairment in young people. Overall, closed-head injuries and other forms of mild traumatic brain injury account for about 75% of the estimated 1.7 million brain injuries that occur annually in the United States. Brain injuries such as closed-head injuries may result in lifelong physical, cognitive, or psychological impairment and, thus, are of utmost concern with regards to public health.
Neurogenic shock is a distributive type of shock resulting in hypotension, often with bradycardia, caused by disruption of autonomic nervous system pathways. It can occur after damage to the central nervous system, such as spinal cord injury and traumatic brain injury. Low blood pressure occurs due to decreased systemic vascular resistance resulting from loss of sympathetic tone, which in turn causes blood pooling within the extremities rather than being available to circulate throughout the body. The slowed heart rate results from a vagal response unopposed by a sympathetic nervous system (SNS) response. Such cardiovascular instability is exacerbated by hypoxia, or treatment with endotracheal or endobronchial suction used to prevent pulmonary aspiration.
Hyperkinesia refers to an increase in muscular activity that can result in excessive abnormal movements, excessive normal movements, or a combination of both. Hyperkinesia is a state of excessive restlessness which is featured in a large variety of disorders that affect the ability to control motor movement, such as Huntington's disease. It is the opposite of hypokinesia, which refers to decreased bodily movement, as commonly manifested in Parkinson's disease.
Acute stress disorder is a psychological response to a terrifying, traumatic or surprising experience. It may bring about delayed stress reactions if not correctly addressed. Acute stress may present in reactions which include but are not limited to: intrusive or dissociative symptoms, and reactivity symptoms such as avoidance or arousal. Reactions may be exhibited for days or weeks post the traumatic event.
Brain herniation is a potentially deadly side effect of very high pressure within the skull that occurs when a part of the brain is squeezed across structures within the skull. The brain can shift across such structures as the falx cerebri, the tentorium cerebelli, and even through the foramen magnum. Herniation can be caused by a number of factors that cause a mass effect and increase intracranial pressure (ICP): these include traumatic brain injury, intracranial hemorrhage, or brain tumor.
Spasmodic torticollis is an extremely painful chronic neurological movement disorder causing the neck to involuntarily turn to the left, right, upwards, and/or downwards. The condition is also referred to as "cervical dystonia". Both agonist and antagonist muscles contract simultaneously during dystonic movement. Causes of the disorder are predominantly idiopathic. A small number of patients develop the disorder as a result of another disorder or disease. Most patients first experience symptoms midlife. The most common treatment for spasmodic torticollis is the use of botulinum toxin type A.
Post-concussion syndrome (PCS), also known as persisting symptoms after concussion, is a set of symptoms that may continue for weeks, months, years after a concussion. PCS is medically classified as a mild traumatic brain injury (TBI). About 35% of people with concussion experience persistent or prolonged symptoms 3 to 6 months after injury. Prolonged concussion is defined as having concussion symptoms for over four weeks following the first accident in youth and for weeks or months in adults.
Pseudobulbar affect (PBA), or emotional incontinence, is a type of neurological disorder characterized by uncontrollable episodes of crying or laughing. PBA occurs secondary to a neurologic disorder or brain injury. Patients may find themselves crying uncontrollably at something that is only slightly sad, being unable to stop themselves for several minutes. Episodes may also be mood-incongruent: a patient may laugh uncontrollably when angry or frustrated, for example. Sometimes, the episodes may switch between emotional states, resulting in the patient crying uncontrollably before dissolving into fits of laughter.
GLUT1 deficiency syndrome, also known as GLUT1-DS, De Vivo disease or Glucose transporter type 1 deficiency syndrome, is an autosomal dominant genetic metabolic disorder associated with a deficiency of GLUT1, the protein that transports glucose across the blood brain barrier. Glucose Transporter Type 1 Deficiency Syndrome has an estimated birth incidence of 1 in 90,000 to 1 in 24,300. This birth incidence translates to an estimated prevalence of 3,000 to 7,000 in the U.S.
Paroxysmal exercise-induced dystonia or PED is a rare neurological disorder characterized by sudden, transient, involuntary movements, often including repetitive twisting motions and painful posturing triggered by exercise or other physical exertion. PED is in the class of paroxysmal dyskinesia which are a group of rare movement disorders characterized by attacks of hyperkinesia with intact consciousness. The term paroxysmal indicates that the episodes are sudden and short lived and usually unpredicted, and return to normal is rapid. The number of reported cases of people with PED is very small leading to difficulty in studying and classifying this disease and most studies are limited to a very small number of test subjects.
Traumatic brain injury can cause a variety of complications, health effects that are not TBI themselves but that result from it. The risk of complications increases with the severity of the trauma; however even mild traumatic brain injury can result in disabilities that interfere with social interactions, employment, and everyday living. TBI can cause a variety of problems including physical, cognitive, emotional, and behavioral complications.
Syncope, commonly known as fainting, or passing out, is a loss of consciousness and muscle strength characterized by a fast onset, short duration, and spontaneous recovery. It is caused by a decrease in blood flow to the brain, typically from low blood pressure. There are sometimes symptoms before the loss of consciousness such as lightheadedness, sweating, pale skin, blurred vision, nausea, vomiting, or feeling warm. Syncope may also be associated with a short episode of muscle twitching. Psychiatric causes can also be determined when a patient experiences fear, anxiety, or panic; particularly before a stressful event, usually medical in nature. When consciousness and muscle strength are not completely lost, it is called presyncope. It is recommended that presyncope be treated the same as syncope.
Basal ganglia disease is a group of physical problems that occur when the group of nuclei in the brain known as the basal ganglia fail to properly suppress unwanted movements or to properly prime upper motor neuron circuits to initiate motor function. Research indicates that increased output of the basal ganglia inhibits thalamocortical projection neurons. Proper activation or deactivation of these neurons is an integral component for proper movement. If something causes too much basal ganglia output, then the ventral anterior (VA) and ventral lateral (VL) thalamocortical projection neurons become too inhibited, and one cannot initiate voluntary movement. These disorders are known as hypokinetic disorders. However, a disorder leading to abnormally low output of the basal ganglia leads to reduced inhibition, and thus excitation, of the thalamocortical projection neurons which synapse onto the cortex. This situation leads to an inability to suppress unwanted movements. These disorders are known as hyperkinetic disorders.