Plexopathy is a disorder affecting a of nerves, blood vessels, or lymph vessels. The region of nerves it affects are at the brachial or lumbosacral plexus. Symptoms include pain, loss of motor control, and sensory deficits.

There are two main types of plexopathy: brachial plexopathy and lumbosacral plexopathy. They are usually caused from some sort of localized trauma such as a dislocated shoulder. The disorder can also be caused secondary to a compression, co-morbid vascular disease, infection, or may be idiopathic with an unknown cause. Both plexopathies can also occur as a consequence of radiation therapy, sometimes after 30 or more years have passed, in conditions known as Radiation-induced Brachial Plexopathy (RIBP) and Radiation-induced Lumbosacral Plexopathy (RILP).

The first steps in the evaluation and later management of plexopathy would consist of gathering a medical history and conducting a physical examination by a healthcare clinician. Motor function defect patterns detected within either the upper or lower extremities help with diagnosis of the disorder.

X-rays of the cervical spine, chest, and shoulder are usually ordered if symptoms point to acute Brachial plexopathy. If the physical history reveals a history of diabetes, collagen vascular disease, or symptoms of infection, the physician may order a series of blood tests including a complete blood count (CBC) and a comprehensive metabolic panel (CMP).

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.

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.

Sensory symptoms are gradually followed by motor symptoms. Motor symptoms may include muscle cramps and weakness, erectile dysfunction in men, problems urinating, constipation, and diarrhea. Individuals also may experience muscle wasting and decreased or absent deep tendon reflexes. Some people may experience frequent falls and gait unsteadiness due to ataxia. This ataxia may be caused by cerebellar degeneration, sensory ataxia, or distal muscle weakness. Over time, alcoholic polyneuropathy may also cause difficulty swallowing (dysphagia), speech impairment (disarthria), muscle spasms, and muscle atrophy.

In addition to alcoholic polyneuropathy, the individual may also show other related disorders such as Wernicke-Korsakoff syndrome and cerebellar degeneration that result from alcoholism-related nutritional disorders.

Common manifestations of sensory issues include numbness or painful sensations in the arms and legs, abnormal sensations like “pins and needles,” and heat intolerance. Pain experienced by individuals depends on the severity of the polyneuropathy. It may be dull and constant in some individuals while being sharp and lancinating in others. In many subjects, tenderness is seen upon the palpitation of muscles in the feet and legs. Certain people may also feel cramping sensations in the muscles affected and others say there is a burning sensation in their feet and calves.

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.

Neuropsychiatric systemic lupus erythematosus or NPSLE refers to the neurological and psychiatric manifestations of systemic lupus erythematosus. SLE is a disease in which the immune system attacks the body's own cells and tissues. It can affect various organs or systems of the body. It is estimated that over half of people with SLE have neuropsychiatric involvement.

Inflammation of the pleurae known as pleurisy can rarely give rise to shrinking lung syndrome. SLE can cause pleuritic pain and also give rise to shrinking lung syndrome, involving a reduced lung volume. Other associated lung conditions include pneumonitis, chronic diffuse interstitial lung disease, pulmonary hypertension, pulmonary emboli, and pulmonary hemorrhage.

Neuropsychiatric syndromes can result when SLE affects the central or peripheral nervous system. The American College of Rheumatology defines 19 neuropsychiatric syndromes in systemic lupus erythematosus. The diagnosis of neuropsychiatric syndromes concurrent with SLE (now termed as NPSLE), is one of the most difficult challenges in medicine, because it can involve so many different patterns of symptoms, some of which may be mistaken for signs of infectious disease or stroke.

A common neurological disorder people with SLE have is headache, although the existence of a specific lupus headache and the optimal approach to headache in SLE cases remains controversial.

Other common neuropsychiatric manifestations of SLE include cognitive dysfunction, mood disorder, cerebrovascular disease, seizures, polyneuropathy, anxiety disorder, psychosis, depression, and in some extreme cases, personality disorders. Steroid psychosis can also occur as a result of treating the disease. It can rarely present with intracranial hypertension syndrome, characterized by an elevated intracranial pressure, papilledema, and headache with occasional abducens nerve paresis, absence of a space-occupying lesion or ventricular enlargement, and normal cerebrospinal fluid chemical and hematological constituents.

More rare manifestations are acute confusional state, Guillain–Barré syndrome, aseptic meningitis, autonomic disorder, demyelinating syndrome, mononeuropathy (which might manifest as mononeuritis multiplex), movement disorder (more specifically, chorea), myasthenia gravis, myelopathy, cranial neuropathy and plexopathy.

Neurological disorders contribute to a significant percentage of morbidity and mortality in people with lupus. As a result, the neural side of lupus is being studied in hopes of reducing morbidity and mortality rates. One aspect of this disease is severe damage to the epithelial cells of the blood–brain barrier. In certain regions, depression affects up to 60% of women with SLE.