Dysautonomia



Most chronic diseases are accompanied by more or less prominent dysautonomia symptoms, which often and visibly worsen patients' quality of life. It could be chronic or acute, progressive, or reversible. Dysautonomia can occur in several common illnesses, including diabetes and alcoholism. Dysautonomia can also be the main condition or co-occur with degenerative neurological disorders like Parkinson's.

What is Dysautonomia?

Dysautonomia is characterized by a failure or increase in the autonomic nervous system's sympathetic or parasympathetic component activity (ANS). Clinical signs include reduced lacrimation, poor thermoregulation, orthostatic hypotension (hypotension, orthostatic), fixed pupils, increased perspiration, loss of pain and temperature sensitivity, and lack of reflexes. These signs are evident at birth. Pathologic hallmarks include a decrease in the number of small-diameter peripheral nerve fibers and autonomic ganglion neurons.

Types of Dysautonomia

At least 15 different kinds of dysautonomia exist.

  • POTS − One of the most prevalent autonomic disorders, postural orthostatic tachycardia syndrome (POTS), includes a variety of clinical symptoms, including postural tachycardia, dizziness, orthostatic intolerance, presyncope, and exercise intolerance.

  • NCS − The syndrome of neurocardiogenic syncope is defined as "a normally self-limited episode of systemic hypotension marked by both bradycardia (asystole or relative bradycardia) and peripheral vasodilation."

  • Multiple System Atrophy − Multiple System Atrophy (MSA) is a rare neurological disorder characterised by a combination of autonomic dysfunction and motor involvement. It can be extrapyramidal (MSA-P) or cerebellar (MSA-C).

  • Autonomic Dysreflexia − After a spinal cord injury, a condition known as autonomic dysreflexia frequently develops, typically when the damage has occurred above the T6 level. Up to 90% of individuals with cervical spinal or high-thoracic spinal cord injuries are at greater risk than those with lower levels of spinal cord injury. When there is a noxious stimulus below the level of the spinal cord injury, dysregulation of the autonomic nervous system causes an uncoordinated sympathetic response that could result in a possibly fatal hypertensive crisis.

  • Baroreflex Failure − The body partially regulates healthy blood pressure through the baroreflex mechanism. Stretch receptors, known as baroreceptors, are found in significant blood arteries, and they send signals to the brain stem when they notice stretching in the artery walls. If these signals are ignored, a person's blood pressure may drop dangerously low while they are at rest or may dangerously increase during stressful periods.

  • Diabetic Autonomic Neuropathy − Among the many significant complications of diabetes, diabetic autonomic neuropathy (DAN) is a typical occurrence. The illness affects the nerves that regulate the heart, genitalia, bladder, digestive system, and other organs.

  • Familial Dysautonomia (FD) − It falls under the larger category of hereditary sensory and autonomic neuropathies, each of which is brought on by a unique genetic mistake. It is a neurodevelopmental genetic condition. Pathological changes include fewer unmyelinated and small-fiber neurons. Clinical characteristics demonstrate the extensive participation of sensory and autonomic neurons. Sensory loss includes impaired pain and temperature sensation. Dysphagia, vomiting episodes, labile blood pressure, and sudomotor dysfunction are autonomic symptoms. Ataxia and emotional instability are symptoms of central dysfunction.

Symptoms

Dysautonomia manifests a wide range of clinical signs and symptoms, including exhaustion, unstable blood pressure, orthostatic hypotension, dysfunction in heart rate variability (HRV), the emergence of impotence, dysfunction of the bladder, and impairment of bowel functions. In FD patients, anxiety is the most prevalent psychiatric condition. Even a small amount of anxiety causes noticeable hypertension and tachycardia, which can lead to nausea and vomiting. About 10% of people with FD experience trichotillomania, compulsive hair pulling, and skin or nail picking. Deep wounds and scars may result from the inability to feel pain.

Patients with FD may experience a range of behavior problems. Psychosis may happen. During a hypertensive-vomiting crisis, caregivers typically report seeing patients become withdrawn or agitated. Drug-seeking behavior coupled with benzodiazepine addiction is a frequently overlooked psychiatric symptom. Studies on primary and secondary autonomic diseases frequently mention the symptoms of orthostatic intolerance. Orthostatic intolerance symptoms typically signal the beginning of the dysregulation of the ANS-reliant neuronal processes governing brain flow.

Causes

Various variables can contribute to autonomic dysfunction, and many reasons may coexist in the same patient. The autonomic nervous system is susceptible to many disorders due to its expansive nature, and the following are the most prevalent reasons known to produce autonomic dysfunction −

  • Inherited diseases include Fabry disease, inherited sensory-autonomic neuropathy, and Porphyrias, amyloidosis.

  • Familial dysautonomia and dopamine-beta-hydroxylase deficiency are examples of genetic illnesses.

  • Guillain-Barre syndrome, Autoimmune autonomic ganglionopathy, Lambert-Eaton myasthenic syndrome, rheumatoid arthritis, Sjogren syndrome, and systemic lupus erythematosus are all autoimmune diseases.

  • Abnormal reflex responses in carotid sinus hypersensitivity, vasovagal syncope, and other neuro-meditated syncopes, as well as perhaps in postural tachycardia syndrome (PoTS)

  • Excessive activation is linked to abnormal sweating responses, such as in widespread or localized hyperhidrosis.

  • Nutritional/ Metabolic: Diabetes and vitamin B12 deficiency

  • Parkinson's disease, multiple system atrophy/Shy-Drager syndromes, pure autonomic failure presenting or suffering from orthostatic hypotension, and fixed heart rate responses are examples of degenerative neurologic illnesses.

  • Botulism, Chagas disease, human immunodeficiency virus (HIV), leprosy, Lyme disease, and tetanus are all infections.

  • Brain tumors and paraneoplastic disorders are examples of neoplasia.

  • Several medicines have pharmacologic effects that interfere with normal autonomic function and cause symptoms, including alpha- and beta-blocker-induced orthostatic hypotension.

  • Traumatic or tumoral spinal cord damage at various levels resulting in autonomic dysreflexia.

  • Chronic liver disease/uremic neuropathy.

Epidemiology

Autonomic dysfunction is not uncommon in general. The most prevalent autonomic dysfunction occurs in the cardiovascular control sphere and is characterized by an aberrant vasovagal response, which causes syncope. Other typical symptoms include postural tachycardia syndrome (POTS) or abnormalities associated with Parkinson's disease and other parkinsonism. Urinary incontinence, as seen in multiple sclerosis and other nervous system illnesses, is unspecific but relatively uncommon compared to other areas of autonomic regulation. Some autonomic disruption symptoms, such as face vasomotor and ocular symptoms in trigeminal autonomic headaches, are of secondary importance but aid in diagnosis.

Treatment

The goal of treating FD is to lessen the catecholamine surges brought on by baroreflex failure. To avoid respiratory failure, neurogenic dysphagia must be managed with good protection of the airway passageways and rapid aspiration pneumonia treatment. The possibility of respiratory depression should be considered when using sedative drugs. When used during sleep, non-invasive ventilation efficiently controls apneas and prevents hypercapnia. Compounds that elevate IKAP (ELP-1) levels are undergoing clinical trials to see if they can stop or halt the progression of the illness.

The management of anxiety in FD is challenging. Benzodiazepines, such as diazepam, should only be administered occasionally since they impair mood and ventilatory drive. Despite the absence of controlled research, selective serotonin reuptake inhibitors can occasionally be helpful. Psychotherapy and behavioral approaches can often help with anxiety management, but they take patience and a long-term time commitment.

Conclusion

It is crucial to take family dynamics into careful account. Any FD patient should have clear expectations and boundaries, which should be addressed with families. Parental counseling is vital for setting realistic expectations. The cognitive performance varies greatly between FD patients. Patients at one end of the spectrum cannot speak or regulate their bowels or bladder, while those at the other end are capable of finishing college and holding down a full-time job. Poor concentration and issues with learning are both prominent. Drugs that cause significant hypertension, such as stimulants and norepinephrine reuptake inhibitors, should be avoided. Numerous patients need specialized education programs.


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