Neuropathy disorders usually have onset in childhood or young adulthood. Motor symptoms seem to be more predominant that sensory symptoms. Symptoms of these disorders include: fatigue, pain, lack of balance, lack of feeling, lack of reflexes, and lack of sight and hearing, which result from muscle atrophy. Patients can also suffer from high arched feet, hammer toes, foot drop, foot deformities, and scoliosis. These symptoms are a result of severe muscular weakness and atrophy. In patients suffering from demyelinating neuropathy, symptoms are due to slow nerve conduction velocities, however people with axonal degradation have average to normal nerve conduction velocities.

Mononeuritis multiplex, occasionally termed polyneuritis multiplex, is simultaneous or sequential involvement of individual noncontiguous nerve trunks, either partially or completely, evolving over days to years and typically presenting with acute or subacute loss of sensory and motor function of individual nerves. The pattern of involvement is asymmetric, however, as the disease progresses, deficit(s) becomes more confluent and symmetrical, making it difficult to differentiate from polyneuropathy. Therefore, attention to the pattern of early symptoms is important.

Mononeuritis multiplex also may cause pain, which is characterized as deep, aching pain that is worse at night and frequently in the lower back, hip, or leg. In people with diabetes mellitus, mononeuritis multiplex typically is encountered as acute, unilateral, and severe thigh pain followed by anterior muscle weakness and loss of knee reflex.

Electrodiagnostic medicine studies will show multifocal sensory motor axonal neuropathy.

It is caused by, or associated with, several medical conditions:

Autonomic neuropathy 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, 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.

The signs and symptoms of autonomic neuropathy include the following:

- Urinary bladder conditions: bladder incontinence or urine 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).

- Other areas: hypoglycemia unawareness, genital impotence, sweat disturbances

Patients with hereditary motor and sensory neuropathies are diagnosed through a physical evaluation that looks for muscle atrophy, weakness, and sensory responses. In addition to this, EMG (electromyography) and motor nerve conduction tests can help clinicians decide what type of motor and sensory neuropathy it is and how severe the disease is. Final confirmation can come through genetic testing.

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.

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).

Usually, the first respiratory symptoms are dyspnea and paradoxical respirations which then escalate within the first few months of life to diaphragmatic paralysis. The symptoms of diaphragmatic paralysis come on very rapidly and without warning, and the patient is often rushed to a hospital where they are placed on a ventilator for respiratory support. Due to the severe nature of diaphragmatic paralysis the patient eventually needs continuous ventilation support to survive. Continuous ventilation, however, may in itself cause damage to the anatomy of the lungs.

In addition to diaphragmatic paralysis other issues may arise: as the name suggests, the distal limbs are most affected with symptoms of weakness, restricting mobility due to (near-)paralysis of the distal limbs as well as the head and neck. Also, dysfunction of the peripheral nerves and the autonomic nervous system may occur. Due to these dysfunctions the patients have been shown to suffer from excessive sweating and irregular heartbeat. The deep tendon reflex is also lost in patients with DSMA1.

Uterine growth retardation and poor foetal movement have been observed in severe DSMA1 cases.

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.

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.

DSMA1 was identified and classified as a sub-group of spinal muscular atrophies (SMA) in 1974. Currently, various classifications include DSMA1 among general spinal muscular atrophies or distal hereditary motor neuropathies, though the latter has been argued to be more correct.

Congenital insensitivity to pain with anhidrosis (CIPA), also known as hereditary sensory and autonomic neuropathy type IV (HSAN IV), is characterized by insensitivity to pain, anhidrosis (the inability to sweat), and intellectual disability. The ability to sense all pain (including visceral pain) is absent, resulting in repeated injuries including: oral self-mutilation (biting of tongue, lips, and buccal mucosa); biting of fingertips; bruising, scarring, and infection of the skin; multiple bone fractures (many of which fail to heal properly); and recurrent joint dislocations resulting in joint deformity. Sense of touch, vibration, and position are normal. Anhidrosis predisposes to recurrent febrile episodes that are often the initial manifestation of CIPA. Hypothermia in cold environments also occurs. Intellectual disability of varying degree is observed in most affected individuals; hyperactivity and emotional lability are common.

Hereditary sensory neuropathy type IV (HSN4) is a rare genetic disorder characterized by the loss of sensation (sensory loss), especially in the feet and legs and, less severely, in the hands and forearms. The sensory loss is due to abnormal functioning of small, unmyelinated nerve fibers and portions of the spinal cord that control responses to pain and temperature as well as other involuntary or automatic body processes. Sweating is almost completely absent with this disorder. Intellectual disability is usually present.

Type 4, congenital insensitivity to pain with anhidrosis (CIPA), is an autosomal recessive condition and affected infants present with episodes of hyperthermia unrelated to environmental temperature, anhidrosis and insensitivity to pain. Palmar skin is thickened and charcot joints are commonly present. NCV shows motor and sensory nerve action potentials to be normal. The histopathology of peripheral nerve biopsy reveals absent small unmyelinated fibers and mitochondria are abnormally enlarged.

Management of Hereditary sensory and autonomic neuropathy Type 4:

Treatment of manifestations: Treatment is supportive and is best provided by specialists in pediatrics, orthopedics, dentistry, ophthalmology, and dermatology. For anhidrosis: Monitoring body temperature helps to institute timely measures to prevent/manage hyperthermia or hypothermia. For insensitivity to pain: Modify as much as reasonable a child’s activities to prevent injuries. Inability to provide proper immobilization as a treatment for orthopedic injuries often delays healing; additionally, bracing and invasive orthopedic procedures increase the risk for infection. Methods used to prevent injuries to the lips, buccal mucosa, tongue, and teeth include tooth extraction, and/or filing (smoothing) of the sharp incisal edges of teeth, and/or use of a mouth guard. Skin care with moisturizers can help prevent palmar and plantar hyperkeratosis and cracking and secondary risk of infection; neurotrophic keratitis is best treated with routine care for dry eyes, prevention of corneal infection, and daily observation of the ocular surface. Interventions for behavioral, developmental, and motor delays as well as educational and social support for school-age children and adolescents are recommended.

Prevention of secondary complications: Regular dental examinations and restriction of sweets to prevent dental caries; early treatment of dental caries and periodontal disease to prevent osteomyelitis of the mandible. During and following surgical procedures, potential complications to identify and manage promptly include hyper- or hypothermia and inadequate sedation, which may trigger unexpected movement and result in secondary injuries.

At the beginning, affected individuals often notice the loss of pain and temperature sensation or all sensory modalities in their feet. As the disease progresses, the sensory abnormalities may extend up to the knees. However, they often do not notice sensory loss for a long time. Many affected individuals only become aware of the disease when they notice painless injuries and burns or when they seek medical advice for slowly healing wounds or foot ulcers. Foot ulcerations may appear due to permanent pressure, such as long walks or badly fitting shoes. Minor wounds or blisters may then lead to deep foot ulcerations. Once infection occurs, complications such as inflammation and destruction of the underlying bones may follow. Affected individuals who do not lose sensation may experience spontaneous pain. In addition, many affected individuals exhibit, to a variable degree, symmetrical distal muscle weakness and wasting.

HSAN I is characterized by marked sensory disturbances mainly as the loss of pain and temperature sensation in the distal parts of the lower limbs. The loss of sensation can also extend to the proximal parts of the lower limbs and the upper limbs as the disease progresses. Some affected individuals do not lose sensation, but instead experience severe shooting, burning, and lancinating pains in the limbs or in the trunk. Autonomic disturbances, if present, manifest as decreased sweating. The degree of motor disturbances is highly variable, even within families, ranging from absent to severe distal muscle weakness and wasting.

The disease progresses slowly, but often disables the affected individuals severely after a long duration. The onset of the disease varies between the 2nd and 5th decade of life, albeit congenital or childhood onset has occasionally been reported. With the progression of the disease, the affected individuals lose the ability to feel pain in their feet and legs. Minor injuries in the painless area can result in slow-healing wounds which, if not immediately recognized, can develop into chronic ulcerations. Once infection occurs, these ulcerations can result in severe complications that lead to foot deformity, such as inflammation of the underlying bones, spontaneous bone fractures, and progressive degeneration of weight-bearing joints. Furthermore, foot deformity promotes skin changes such as hyperkeratosis at pressure points. These complications may necessitate amputation of the affected foot.

Biopsies of severely affected sural nerve (short saphenous nerve) in patients with HSAN I showed evidence of neuronal degeneration. Only a very few myelinated fibers were observed some of which showed a sign of primary (segmental) demyelination. A reasonable number of unmyelinated axons remained, although the presence of stacks of flattened Schwann cell processes suggested unmyelinated axon loss. Electrophysiological testing provides additional evidence that neuronal degeneration underlies the disease. Sensory potentials are usually absent in the lower limbs but are often recordable or even normal in the upper limbs of the patients. In addition, motor conduction is slow, possibly implying a demyelinating process.

The syndrome typically presents as a progressive flaccid symmetric paralysis with areflexia, often causing respiratory failure. Electromyographic studies and nerve conduction studies show normal motor conduction velocity and latency with decreased amplitude of compound muscle action potentials. F wave and sensory nerve action potentials are often normal in this illness. Pathologically, it is a noninflammatory axonopathy without demyelination. Antibodies attack the coating of the motor neurons without causing inflammation or loss of myelin. It does not affect sensory neurons, so sensation remains intact despite loss of movement.

Acute motor axonal neuropathy (AMAN) is a variant of Guillain–Barré syndrome. It is characterized by acute paralysis and loss of reflexes without sensory loss. Pathologically, there is motor axonal degeneration with antibody-mediated attacks of motor nerves and nodes of Ranvier.

Signs and symptoms of proximal diabetic neuropathy depend on the region of the plexus which is affected. The first symptom is usually pain in the buttocks, hips, thighs or legs. This pain most commonly affects one side of the body and can either start gradually or come on suddenly. This is often followed by variable weakness in the proximal muscles of the lower limbs. These symptoms, although often beginning on one side, can also spread . Weakness in proximal diabetic neuropathy is caused by denervation of the specific muscles innervated by regions of the plexus affected and can thus these muscles may start exhibiting fasciculations.

Note that diabetic amyotrophy is a condition caused by diabetes mellitus, but separate from the more common condition of polyneuropathy.

People with CIP/CIM have diffuse, symmetric, flaccid muscle weakness. CIP/CIM typically develops in the setting of a critical illness and immobilization, so patients with CIP/CIM are often receiving treatment in the intensive care unit (ICU).

Weakness (motor deficits) occurs in generalized fashion, rather than beginning in one region of the body and spreading. Limb and respiratory (diaphragm) muscles are especially affected. The muscles of the face are usually spared, but in rare cases, the eye muscles may be weakened, leading to ophthalmoplegia.

Respiratory difficulties can be caused by atrophy of the muscles between the ribs (intercostals), atrophy of the diaphragm muscle, and degeneration of the nerve that stimulates the diaphragm (phrenic nerve). This can prolong the time the wean a person off of a breathing machine (mechanical ventilation) by as much as 7 – 13 days.

Deep tendon reflexes may be lost or diminished, and there may be bilateral symmetric flaccid paralysis of the arms and legs. The nervous system manifestations are typically limited to peripheral nerves, as the central nervous system is usually unaffected.

There are several types of immune-mediated neuropathies recognised. These include

- Chronic inflammatory demyelinating polyneuropathy (CIPD) with subtypes:

- Classical CIDP

- CIDP with diabetes

- CIDP/monoclonal gammopathy of undetermined significance

- Sensory CIDP

- Multifocal motor neuropathy

- Multifocal acquired demyelinating sensory and motor neuropathy (Lewis-Sumner syndrome)

- Multifocal acquired sensory and motor neuropathy

- Distal acquired demyelinating sensory neuropathy

- Guillain-Barre syndrome with subtypes:

- Acute inflammatory demyelinating polyradiculoneuropathy

- Acute motor axonal neuropathy

- Acute motor and sensory axonal neuropathy

- Acute pandysautonomia

- Miller Fisher syndrome

- IgM monoclonal gammopathies with subtypes:

- Waldenstrom's macroglobulinemia

- Mixed cryoglobulinemia, gait ataxia, late-onset polyneuropathy syndrome

- Myelin-associated glycoprotein-associated gammopathy, polyneuropathy, organomegaly, endocrinopathy, M-protein and skin changes syndrome (POEMS)

For this reason a diagnosis of chronic inflammatory demyelinating polyneuropathy needs further investigations.

The diagnosis is usually provisionally made through a clinical neurological examination. Patients usually present with a history of weakness, numbness, tingling, pain and difficulty in walking. They may additionally present with fainting spells while standing up or burning pain in extremities. Some patients may have sudden onset of back pain or neck pain radiating down the extremities, usually diagnosed as radicular pain. These symptoms are usually progressive and may be intermittent.

Autonomic system dysfunction can occur; in such a case, the patient would complain of orthostatic dizziness, problems breathing, eye, bowel, bladder and cardiac problems. The patient may also present with a single cranial nerve or peripheral nerve dysfunction.

On examination the patients may have weakness, and loss of deep tendon reflexes (rarely increased or normal). There may be atrophy (shrinkage) of muscles, fasciculations (twitching) and loss of sensation. Patients may have multi-focal motor neuropathy, as they have no sensory loss.

Most experts consider the necessary duration of symptoms to be greater than 8 weeks for the diagnosis of CIDP to be made.

Typical diagnostic tests include:

- Electrodiagnostics – electromyography (EMG) and nerve conduction study (NCS). In usual CIDP, the nerve conduction studies show demyelination. These findings include:

1. a reduction in nerve conduction velocities;

2. the presence of conduction block or abnormal temporal dispersion in at least one motor nerve;

3. prolonged distal latencies in at least two nerves;

4. absent F waves or prolonged minimum F wave latencies in at least two motor nerves. (In some case EMG/NCV can be normal).

- Serum test to exclude other autoimmune diseases.

- Lumbar puncture and serum test for anti-ganglioside antibodies. These antibodies are present in the branch of CIDP diseases comprised by anti-GM1, anti-GD1a, and anti-GQ1b.

- Sural nerve biopsy; biopsy is considered for those patients in whom the diagnosis is not completely clear, when other causes of neuropathy (e.g., hereditary, vasculitic) cannot be excluded, or when profound axonal involvement is observed on EMG.

- Ultrasound of the periferal nerves may show swelling of the affected nerves

- MRI can also be used in the diagnosic workup

In some cases electrophysiological studies fail to show any evidence of demyelination. Though conventional electrophysiological diagnostic criteria are not met, the patient may still respond to immunomodulatory treatments. In such cases, presence of clinical characteristics suggestive of CIDP are critical, justifying full investigations, including sural nerve biopsy.

Hereditary sensory and autonomic neuropathy type I (HSAN I) or hereditary sensory neuropathy type I (HSN I) is a group of autosomal dominant inherited neurological diseases that affect the peripheral nervous system particularly on the sensory and autonomic functions. The hallmark of the disease is the marked loss of pain and temperature sensation in the distal parts of the lower limbs. The autonomic disturbances, if present, manifest as sweating abnormalities.

The beginning of the disease varies between adolescence and adulthood. Since affected individuals cannot feel pain, minor wounds or blisters in the painless area may not be immediately recognized and can develop into extensive and deep foot ulcerations. Once infection occurs, the complications such as inflammation and progressive destruction of the underlying bones may follow and may require amputation of the surrounding area.

HSAN I is the most common type among the five types of HSAN. As a heterogeneous group of diseases, HSAN I can be divided into five subtypes HSAN IA-E. Most of the genes associated with the diseases have been identified. However, the molecular pathways leading to the manifestation of the diseases are not fully understood. Therefore, the potential targets for therapeutic interventions are not known. Moreover, gene-based therapies for patients with the diseases are not available to date, hence supportive care is the only treatment available for the patients.

Infantile Progressive Bulbar palsy is a rare type of progressive bulbar palsy that occurs in children. The disease exists in both rapid and slow onsets, and involves inflammation of the gray matter of the bulb. Infantile PBP is a disease that manifests itself in two forms: Fazio Londe syndrome (FL) and Brown-Vialetto-Van-Laere syndrome (BVVL).

Persons with HDLS can suffer from tremors, decreased body movement, unsteadiness (Parkinsonism, muscles on one side of the body in constant contraction (spastic hemiparesis), impairment in motor and sensory function in the lower extremities (paraparesis), paralysis resulting in partial or total loss of all extremities and torso (tetraparesis), and the lack of voluntary coordination of muscle movements (ataxia).

A number of terms are used to describe critical illness polyneuropathy, partially because there is often neuropathy and myopathy in the same person, and nerve and muscle degeneration are difficult to distinguish from each other in this condition. Terms used for the condition include: critical illness polyneuromyopathy, critical illness neuromyopathy, and critical illness myopathy and neuropathy (CRIMYNE). Bolton's neuropathy is an older term, which is no longer used.

With symptoms of personality changes, behavioral changes, dementia, depression, and epilepsy, HDLS has been commonly misdiagnosed for a number of other diseases. Dementia or frontotemporal behavioral changes, for example, have commonly steered some clinicians to mistakenly consider diagnoses such as Alzheimer’s disease, frontotemporal dementia or atypical Parkinsonism. The presence of white matter changes has led to misdiagnosis of multiple sclerosis. HDLS commonly manifests with neuropsychiatric symptoms, progressing to dementia, and after a few years shows motor dysfunction. Eventually patients become wheelchair-bound or bedridden.

White matter degeneration is associated with and makes differential diagnoses out of other adult onset leukodystrophies such as metachromatic leukodystrophy (MLD), Krabbe disease (globoid cell leukodystrophy), and X-linked adrenoleukodystrophy (X-ADL).

Chronic inflammatory demyelinating polyneuropathy, also known as Vidaurri's disease, is believed to be due to immune cells, which normally protect the body from foreign infection, incorrectly attacking the nerves in the body instead. As a result, the affected nerves fail to respond, or respond only weakly, and on occasion, inordinately, to stimuli, causing numbing, tingling, pain, progressive muscle weakness, loss of deep tendon reflexes (areflexia), fatigue, and abnormal sensations. The likelihood of progression of the disease is high.

CIDP is under-recognized and under-treated due to its heterogeneous presentation (both clinical and electrophysiological) and the limitations of clinical, serologic, and electrophysiologic diagnostic criteria. Despite these limitations, early diagnosis and treatment is important in preventing irreversible axonal loss and improving functional recovery.

Lack of awareness and treatment of CIDP is also due to limitations of clinical trials. Although there are stringent research criteria for selecting patients to clinical trials, there are no generally agreed-on clinical diagnostic criteria for CIDP due to its different presentations in symptoms and objective data. Application of the present research criteria to routine clinical practice often miss the diagnosis in a majority of patients, and patients are often left untreated despite progression of their disease.

Proximal diabetic neuropathy, more commonly known as diabetic amyotrophy, is a nerve disorder that results as a complication of diabetes mellitus. It can affect the thighs, hips, buttocks or lower legs. Proximal diabetic neuropathy is a peripheral nerve disease (diabetic neuropathy) characterized by muscle wasting or weakness, pain, or changes in sensation/numbness of the leg. Diabetic neuropathy is an uncommon complication of diabetes. It is a type of lumbosacral plexopathy, or adverse condition affecting the lumbosacral plexus.

There are a number of ways that diabetes damages the nerves, all of which seem to be related to increased blood sugar levels over a long period of time. Proximal diabetic neuropathy is one of four types of diabetic neuropathy.

Proximal diabetic neuropathy can occur in type 2 and type 1 diabetes mellitus patients however, it is most commonly found in type 2 diabetics. Proximal neuropathy is the second most common type of diabetic neuropathy and can be resolved with time and treatment.