The signs and symptoms of autonomic neuropathy include the following:

- Urinary bladder conditions: bladder incontinence or urinary retention

- Gastrointestinal tract: dysphagia, abdominal pain, nausea, vomiting, malabsorption, fecal incontinence, gastroparesis, diarrhoea, constipation

- Cardiovascular system: disturbances of heart rate (tachycardia, bradycardia), orthostatic hypotension, inadequate increase of heart rate on exertion

- Respiratory system: impairments in the signals associated with regulation of breathing and gas exchange (central sleep apnea, hypopnea, bradypnea).

- Nervous system: pupillary defect, exaggerated hippus, dizziness or lightheadedness.

- Other areas: hypoglycemia unawareness, genital impotence, sweat disturbances, sicca (dryness).

Primary autonomic failure (also called primary dysautonomia) refers to a category of dysautonomias -- conditions in which the autonomic nervous system does not function properly.

In primary dysautonomias, the autonomic dysfunction occurs as a primary condition (as opposed to resulting from another disease). Autonomic failure is categorized as "primary" when believed to result from a chronic condition characterized by degeneration of the autonomic nervous system, or where autonomic failure is the predominant symptom and its cause is unknown.

Such "primary" dysautonomias are distinguished from secondary dysautonomias, where the dysfunction of the autonomic nervous system is believed to be caused by another disease (e.g. diabetes).

Diseases categorized as primary autonomic failure usually include pure autonomic failure and multiple system atrophy. Many scientists also categorize Parkinson disease and familial dysautonomia as "primary".

Dysautonomia may be due to inherited or degenerative neurologic diseases (primary dysautonomia) or it may occur due to injury of the autonomic nervous system from an acquired disorder (secondary dysautonomia). The most common causes of dysautonomia include

In the sympathetic nervous system (SNS), predominant dysautonomia is common along with fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, and interstitial cystitis, raising the possibility that such dysautonomia could be their common clustering underlying pathogenesis.

In addition to sometimes being a symptom of dysautonomia, anxiety can sometimes physically manifest symptoms resembling autonomic dysfunction. A thorough investigation ruling out physiological causes is crucial, but in cases where relevant tests are performed and no causes are found or symptoms do not match any known disorders, a primary anxiety disorder is possible, but should not be presumed. For such patients, the anxiety sensitivity index may have better predictivity for anxiety disorders, while the Beck anxiety inventory may misleadingly suggest anxiety for patients with dysautonomia.

Autonomic neuropathy (also AN or AAN) is a form of polyneuropathy that affects the non-voluntary, non-sensory nervous system (i.e., the autonomic nervous system), affecting mostly the internal organs such as the bladder muscles, the cardiovascular system, the digestive tract, and the genital organs. These nerves are not under a person's conscious control and function automatically. Autonomic nerve fibers form large collections in the thorax, abdomen, and pelvis outside the spinal cord. They have connections with the spinal cord and ultimately the brain, however. Most commonly autonomic neuropathy is seen in persons with long-standing diabetes mellitus type 1 and 2. In most—but not all—cases, autonomic neuropathy occurs alongside other forms of neuropathy, such as sensory neuropathy.

Autonomic neuropathy is one cause of malfunction of the autonomic nervous system (referred to as dysautonomia), but not the only one; some conditions affecting the brain or spinal cord also may cause autonomic dysfunction, such as multiple system atrophy, and therefore, may cause similar symptoms to autonomic neuropathy.

Although symptoms of AAG can range from patient to patient, hallmark symptoms include:

- gastrointestinal dysmotility

- anhidrosis (decreased ability to sweat)

- bladder dysfunction (neurogenic bladder)

- small fiber peripheral neuropathy

- Severe orthostatic hypotension

- Pupillary dysfunction

- syncope (fainting)

- Sicca syndrome (chronic dryness of the eyes and mouth)

The symptoms of Dysautonomia, which are numerous and vary widely for each individual, are due to inefficient or unbalanced efferent signals sent via both systems. The primary symptoms in individuals with dysautonomia include

A degenerative disease of the autonomic nervous system, symptoms include dizziness and fainting (caused by orthostatic hypotension), visual disturbances and neck pain. Chest pain, fatigue and sexual dysfunction are less common symptoms that may also occur. Symptoms are worse when standing; sometimes one may relieve symptoms by lying down.

Sensory symptoms of small fiber neuropathy are highly variable. Common complaints include paresthesias, dysesthesias, and insensitivity to pain. "Paresthesias" are abnormal sensations. They are often described as numbness, burning, cold, prickling, pins and needles along with other symptoms. "Dysesthesias" are unpleasant sensations, either spontaneous or evoked. A light breeze, the feeling of clothes, or even a soft touch can cause pain.

Insensitivity to pain can be particular problem. One may be bleeding or have a skin injury without even knowing it.

Autoimmune autonomic ganglionopathy (AAG) is an extremely rare form of dysautonomia in which the patients immune system produces ganglionic AChR antibodies, inhibiting ganglionic AChR currents and impairing transmission in autonomic ganglia. Approximately 100 Americans are diagnosed with AAG each year. Symptoms onset can be acute, subacute or gradual.

Like many polyneuropathies, the symptoms are length-dependent, starting in the longer nerves and progressively attack shorter nerves. This means that most often the symptoms start in the feet and progress upwards, and usually symptoms are more severe in the feet. Many patients have a widespread, length independent, or "patchy", presentation which is sporadic and can affect many nerves, including the trigeminal nerve or occipital nerve.

Patients with Fabry disease have isolated small fiber engagement, and can have a more widespread small fiber disruption.

The American College of Rheumatology has outlined 19 syndromes that are seen in NPSLE. These syndromes encompass disorders of the central and peripheral nervous systems:

- Aseptic meningitis

- Cerebrovascular disease

- Demyelinating syndrome

- Headache

- Movement disorder

- Myelopathy

- Seizure disorders

- Acute confusional state

- Anxiety disorder

- Cognitive dysfunction

- Mood disorder

- Psychosis

- Acute inflammatory demyelinating polyradiculoneuropathy

- Autonomic disorder

- Mononeuropathy (single/multiplex)

- Myasthenia gravis

- Cranial neuropathy

- Plexopathy

- Polyneuropathy

Each of the 19 syndromes are also stand-alone diagnoses, which can occur with or without lupus.

The majority of cases involve the central nervous system (CNS), which consists of the brain and spinal cord. The CNS syndromes can be subcategorized as either focal or diffuse. The focal syndromes are neurological, while the diffuse syndromes are psychiatric in nature. The most common CNS syndromes are headache and mood disorder.

Though neuropsychiatric lupus is sometimes referred to as "CNS lupus", it can also affect the peripheral nervous system (PNS). Between 10-15% of people with NPSLE have PNS involvement. Mononeuropathy and polyneuropathy are the most common PNS syndromes.

Among the signs/symptoms of polyneuropathy, which can be divided (into sensory and hereditary) and are consistent with the following:

- "Sensory polyneuropathy" - ataxia, numbness, muscle wasting and paraesthesiae.

- "Hereditary polyneuropathy" - scoliosis and hammer toes

Polyneuropathy ( + + ) is damage or disease affecting peripheral nerves (peripheral neuropathy) in roughly the same areas on both sides of the body, featuring weakness, numbness, and burning pain. It usually begins in the hands and feet and may progress to the arms and legs; and sometimes to other parts of the body where it may affect the autonomic nervous system. It may be acute or chronic. A number of different disorders may cause polyneuropathy, including diabetes and some types of Guillain–Barré syndrome.

Neuritis is a general term for inflammation of a nerve or the general inflammation of the peripheral nervous system. Symptoms depend on the nerves involved, but may include pain, paresthesia (pins-and-needles), paresis (weakness), hypoesthesia (numbness), anesthesia, paralysis, wasting, and disappearance of the reflexes.

Causes of neuritis include:

Those with diseases or dysfunctions of their nerves may present with problems in any of the normal nerve functions. Symptoms vary depending on the types of nerve fiber involved.In terms of sensory function, symptoms commonly include loss of function ("negative") symptoms, including , tremor, impairment of balance, and gait abnormality. Gain of function (positive) symptoms include tingling, pain, itching, crawling, and pins-and-needles.

Motor symptoms include loss of function ("negative") symptoms of weakness, tiredness, muscle atrophy, and gait abnormalities; and gain of function ("positive") symptoms of cramps, and muscle twitch (fasciculations).

In the most common form, length-dependent peripheral neuropathy, pain and parasthesia appears symmetrically and generally at the terminals of the longest nerves, which are in the lower legs and feet. Sensory symptoms generally develop before motor symptoms such as weakness. Length-dependent peripheral neuropathy symptoms make a slow ascent of leg, while symptoms may never appear in the upper limbs; if they do, it will be around the time that leg symptoms reach the knee. When the nerves of the autonomic nervous system are affected, symptoms may include constipation, dry mouth, difficulty urinating, and dizziness when standing.

The variable presentation of ROHHAD includes the following main symptoms:

- Hyperphagia and obesity by age of 10 years - (median age 3 years);

- Respiratory Manifestations:

- Alveolar Hypoventilation (median onset age 6.2 years);

- Cardiorespiratory arrest;

- Reduced Carbon Dioxide Ventilatory Response;

- Obstructive sleep apnea.

- Thermal or other hypothalamic dysregulations, with autonomic dysregulation by median age 3.6 years:

- Failed Growth Hormone Stimulation;

- Adipsic hypernatremia (inability to feel thirst to keep normal hydration);

- Hypernatremia;

- Hyperprolactinemia;

- Hyperphagia;

- Diabetes insipidus;

- Ophthalmologic Manifestations;

- Thermal Dysregulation;

- Gastrointestinal dysmotility;

- Altered Perception of Pain;

- Altered Sweating;

- Cold Hands and Feet.

- Neurobehavioral disorders;

- Tumors of neural crest origin.

Clinically overlapping cases exist because CCHS phenotype can also include autonomic nervous system dysregulation, or tumors of neural crest origin.

The first symptoms of Guillain–Barré syndrome are numbness, tingling, and pain, alone or in combination. This is followed by weakness of the legs and arms that affects both sides equally and worsens over time. The weakness can take half a day to over two weeks to reach maximum severity, and then becomes steady. In one in five people, the weakness continues to progress for as long as four weeks. The muscles of the neck may also be affected, and about half experience involvement of the cranial nerves which supply the head and face; this may lead to weakness of the muscles of the face, swallowing difficulties and sometimes weakness of the eye muscles. In 8%, the weakness affects only the legs (paraplegia or paraparesis). Involvement of the muscles that control the bladder and anus is unusual. In total, about a third of people with Guillain–Barré syndrome continue to be able to walk. Once the weakness has stopped progressing, it persists at a stable level ("plateau phase") before improvement occurs. The plateau phase can take between two days and six months, but the most common duration is a week. Pain-related symptoms affect more than half, and include back pain, painful tingling, muscle pain and pain in the head and neck relating to irritation of the lining of the brain.

Many people with Guillain–Barré syndrome have experienced the signs and symptoms of an infection in the 3–6 weeks prior to the onset of the neurological symptoms. This may consist of upper respiratory tract infection (rhinitis, sore throat) or diarrhea.

In children, particularly those younger than six years old, the diagnosis can be difficult and the condition is often initially mistaken (sometimes for up to two weeks) for other causes of pains and difficulty walking, such as viral infections, or bone and joint problems.

On neurological examination, characteristic features are the reduced power and reduced or absent tendon reflexes (hypo- or areflexia, respectively). However, a small proportion has normal reflexes in affected limbs before developing areflexia, and some may have exaggerated reflexes. In the "Miller Fisher variant" subtype of Guillain–Barré syndrome (see below), a triad of weakness of the eye muscles, abnormalities in coordination, as well as absent reflexes can be found. The level of consciousness is normally unaffected in Guillain–Barré syndrome, but the Bickerstaff brainstem encephalitis subtype may feature drowsiness, sleepiness, or coma.

Five different clinical entities have been described under hereditary sensory and autonomic neuropathies – all characterized by progressive loss of function that predominantly affects the peripheral sensory nerves. Their incidence has been estimated to be about 1 in 25,000.

The most distinctive clinical feature is the absence of overflow tears with emotional crying after age 7 months. This symptom can manifest less dramatically as persistent bilateral eye irritation. There is also a high prevalence of breech presentation. Other symptoms include weak or absent suck and poor tone, poor suck and misdirected swallowing, and red blotching of skin.

Symptoms in an older child with familial dysautonomia might include:

1. Delayed speech and walking

2. Unsteady gait

3. Spinal curvature

4. Corneal abrasion

5. Less perception in pain or temperature with nervous system.

6. Poor growth

7. Erratic or unstable blood pressure.

8. Red puffy hands

9. Dysautonomia crisis: a constellation of symptoms in response to physical and emotional stress; usually accompanied by vomiting, increased heart rate, increase in blood pressure, sweating, drooling, blotching of the skin and a negative change in personality.

The pathology of pure autonomic failure is not yet completely understood. However, a loss of cells in the intermediolateral column of the spinal cord has been documented, as has a loss of catecholamine uptake and catecholamine fluorescence in sympathetic postganglionic neurons. In general, levels of catecholamines in these patients are very low while lying down, and do not increase much upon standing.

In one of the few reported cases, the subject presented with muscle weakness and fatigue, muscle twitching, excessive sweating and salivation, small joint pain, itching and weight loss. The subject also developed confusional episodes with spatial and temporal disorientation, visual and auditory hallucinations, complex behavior during sleep and progressive nocturnal insomnia associated with diurnal drowsiness. There was also severe constipation, urinary incontinence, and excessive lacrimation. When left alone, the subject would slowly lapse into a stuporous state with dreamlike episodes characterized by complex and quasi-purposeful gestures and movements (enacted dreams). Marked hyperhidrosis and excessive salivation were evident. Neurological examination disclosed diffuse muscle twitching and spontaneous and reflex myoclonus, slight muscle atrophy in the limbs, absence of tendon reflexes in the lower limbs and diffuse erythema especially on the trunk with scratching lesions of the skin.

Compulsive behaviours, stereotypies and reduplicative paramnesias can be part of the CNS spectrum.

Morvan's syndrome, or Morvan's fibrillary chorea (MFC), is a rare autoimmune disease named after the nineteenth century French physician Augustin Marie Morvan. "La chorée fibrillaire" was first coined by Morvan in 1890 when describing patients with multiple, irregular contractions of the long muscles, cramping, weakness, pruritus, hyperhidrosis, insomnia, and delirium.

It normally presents with a slow insidious onset over months to years.

Approximately 90% of cases spontaneously go into remission, while the other 10% of cases lead to death.

In 1890, Morvan described a patient with myokymia (muscle twitching) associated with muscle pain, excessive sweating, and disordered sleep.

This rare disorder is characterized by severe insomnia, amounting to no less than complete lack of sleep (agrypnia) for weeks or months in a row, and associated with autonomic alterations consisting of profuse perspiration with characteristic skin miliaria (miliaria rubra, sweat rash or prickly heat), tachycardia, increased body temperature, and hypertension. Patients display a remarkable hallucinatory behavior, and peculiar motor disturbances, which Morvan reported under the term “fibrillary chorea” but which are best described in modern terms as neuromyotonic discharges.

The association of the disease with thymoma, tumour, autoimmune diseases, and autoantibodies suggests an autoimmune or paraneoplastic aetiology. Besides an immune-mediated etiology, it is also believed to occur in gold, mercury, or manganese poisoning.

A quarter of all people with Guillain–Barré syndrome develop weakness of the breathing muscles leading to respiratory failure, the inability to breathe adequately to maintain healthy levels of oxygen and/or carbon dioxide in the blood. This life-threatening scenario is complicated by other medical problems such as pneumonia, severe infections, blood clots in the lungs and bleeding in the digestive tract in 60% of those who require artificial ventilation.

People with this disorder are very likely to injure themselves in ways that would normally be prevented by feeling pain. For example, a patient could burn themselves severely and not even notice. The main features of the disorder are lack of pain sensation, painless injuries of the arms, legs, and oral structures, hyperthermia during hot weather because of inability to sweat, syndromic intellectual disability as a result of hyperthermia, infection and scarring of the tongue, lips and gums, chronic infections of bones and joints, bone fractures, multiple scars, osteomyelitis and joint deformities, which may lead to amputation. Other common problems are eye related, such as infection due to the sufferers rubbing them too hard, too frequently or scratching them during sleep. In addition, patients typically lack unmyelinated and small myelinated nerve fibers in the dorsal root ganglion. Both are responsible for transmitting pain signals. In addition, patients' sweat glands are normal in both structure and function, though they lack innervations by small diameter neurons.

The weakness from LEMS typically involves the muscles of the proximal arms and legs (the muscles closer to the trunk). In contrast to myasthenia gravis, the weakness affects the legs more than the arms. This leads to difficulties climbing stairs and rising from a sitting position. Weakness is often relieved temporarily after exertion or physical exercise. High temperatures can worsen the symptoms. Weakness of the bulbar muscles (muscles of the mouth and throat) is occasionally encountered. Weakness of the eye muscles is uncommon. Some may have double vision, drooping of the eyelids and difficulty swallowing, but generally only together with leg weakness; this too distinguishes LEMS from myasthenia gravis, in which eye signs are much more common. In the advanced stages of the disease, weakness of the respiratory muscles may occur. Some may also experience problems with coordination (ataxia).

Three-quarters of people with LEMS also have disruption of the autonomic nervous system. This may be experienced as a dry mouth, constipation, blurred vision, impaired sweating, and orthostatic hypotension (falls in blood pressure on standing, potentially leading to blackouts). Some report a metallic taste in the mouth.

On neurological examination, the weakness demonstrated with normal testing of power is often less severe than would be expected on the basis of the symptoms. Strength improves further with repeated testing, e.g. improvement of power on repeated hand grip (a phenomenon known as "Lambert's sign"). At rest, reflexes are typically reduced; with muscle use, reflex strength increases. This is a characteristic feature of LEMS. The pupillary light reflex may be sluggish.

In LEMS associated with lung cancer, most have no suggestive symptoms of cancer at the time, such as cough, coughing blood, and unintentional weight loss. LEMS associated with lung cancer may be more severe.