Neurology

NERVE ANATOMY AND TERMINOLOGY

Perikarya—nerve cell body
Axon—transmits neural signal to other neurons or to the organ/muscle
Dendrite—receives neural input from other neurons
Oligodendrocytes—type of glial cell (neural support cell) responsible for myelination of nerves within the CNS
Schwann cell—type of glial cell (neural support cell) responsible for myelination of nerves within the PNS
Myelin—a lipid-rich coating around the neural axons. Produced by Schwann cells (PNS) and oligodendrocytes (CNS). Upon gross inspection, myelin is white and responsible for the “white matter” color of the brain and spinal cord.
Ganglia—a cluster of perikarya located outside the CNS
Nuclei—a cluster of perikarya located within the CNS
Nissl bodies—large granular bodies found in neurons. They are endoplasmic reticulum responsible for protein synthesis.
Node of Ranvier—gaps in the myelin sheath. The action potential signal jumps along the axon from node to node for more rapid signal propagation.
Most nerve cell bodies (perikarya) are found within the CNS, but sensory (afferent) and autonomic (visceral motor) neurons are found outside the
CNS as clusters called ganglia. Sensory (afferent) perikarya are located in the dorsal root ganglia, near but not technically in the CNS.
Perikarya of the autonomic nervous system (sympathetic parasympathetic) are located outside the CNS. Sympathetic perikarya are found in ganglia near the spinal cord, and parasympathetic ganglia are found in the target organ.

Types of Neurons

Afferent	Efferent
Sensory	Motor
Direct signals toward CNS	Direct signals away from the CNS
Ganglia located in dorsal root ganglia (outside the CNS)	Ganglia located in the ventral (anterior) horn (in the CNS)
Mnemonic: SAME (Sensory-Afferent, Motor-Efferent)

NERVE INJURY

Sequence of nerve recovery after injury:

1. Pain

2. Temperature

3. Touch

4. Proprioception

5. Motor

Nerve Injury Classifications

Seddon Classification

Neurapraxia: Bruised nerve. Results in numbness that is reversible.

Axonotmesis: Injury to axon that results in Wallerian degeneration. Nerve will regenerate over several months as long as gap is not too big.

Neurotmesis: Complete severance of the nerve, resulting in irreversible numbness

Sunderland Classification

First degree: A conduction deficit without axonal destruction

Second degree: Axon is severed without reaching the neural tube. Wallerian degeneration with regeneration. Regeneration is likely (axonotmesis).

Third degree: Degeneration of axon with destruction of fascicle with irregular regeneration

Fourth degree: Destruction of axon and fascicle and no destruction of nerve trunk, but a neuroma-in-continuity exists

Fifth degree: Complete loss; neuroma is likely, and spontaneous recovery is rare

NERVE BLOCKS

Field Blocks

Ankle Block

Tibial nerve

Saphenous nerve

Medial dorsal cutaneous nerve

Deep peroneal nerve

Intermediate dorsal cutaneous nerve

Sural nerve

Digital Block (e.g., 3rd)

5th and 6th dorsal digital proper nerve

5th and 6th plantar digital proper nerve

Hallux Block

1st dorsal digital proper nerve

Deep peroneal nerve

1st plantar digital proper nerve

2nd plantar digital proper nerve

Mayo Block (for Bunions)

Saphenous nerve

Deep peroneal nerve

Medial dorsal cutaneous nerve

Medial plantar nerve

Mini-Mayo Block (for Tailor’s Bunion)

Lateral dorsal cutaneous nerve

4th common dorsal digital nerve

Superficial branch of the lateral plantar nerve

4th common plantar digital nerve

Popliteal Block

Sciatic nerve (Injection is given at the posterior knee approximately 7 cm proximal and approximately 1 cm lateral to the transverse popliteal crease. At this level, it shares a neural sheath with the common peroneal nerve.)

For a complete leg block, the saphenous nerve is also injected just distal and anterior to the medial condyle of the tibia.

Local Infiltration

A localized area is flooded with anesthesia without regards to location of specific nerves. Used more commonly for ulcers, warts, and biopsies.

Bier Block (Intravenous Regional Anesthesia)

Veins, arteries, and nerves run together; so by injecting anesthetic into a vein, it diffuses out into the surrounding nerves. A tourniquet is placed around the patient’s calf. An intravenous cannula is then inserted as distally as possible. The leg is then elevated for 3 to 4 minutes, or an Esmarch bandage is used to exsanguinate the extremity. The tourniquet is then inflated. The local anesthesia (usually lidocaine, plain) is then injected. The intravenous cannula is removed prior to preparation for operation. The block will persist as long as the cuff is inflated and disappears shortly following deflation.

DERMATOMES OF THE LOWER EXTREMITY

CUTANEOUS INNERVATION OF THE LOWER EXTREMITY

INNERVATION OF INTRINSIC MUSCLES

Medial Plantar Nerve: (Mnemonic Laff)

1st Lumbrical

Abductor hallucis muscle

Flexor digitorum brevis

Flexor hallucis brevis

Lateral Plantar Nerve

Abductor digiti minimi

Quadratus plantae

2nd lumbrical

3rd lumbrical

4th lumbrical

Deep Branch of the Lateral Plantar Nerve

Adductor hallucis muscle (both heads)

1st dorsal interosseous muscle

2nd dorsal interosseous muscle

3rd dorsal interosseous muscle

1st plantar interosseous muscle

2nd plantar interosseous muscle

Superficial Branch of the Lateral Plantar Nerve

Flexor digiti minimi quinti

4th dorsal interosseous muscle

3rd plantar interosseous muscle

Lateral Terminal Branch of the Deep Peroneal Nerve

Extensor digitorum brevis

ENTRAPMENT NEUROPATHIES

Morton Neuroma

A painful benign fibrotic enlargement of one of the common digital nerves, caused by shearing forces of adjacent metatarsal heads. This process most commonly affects the 3rd common digital nerve and less commonly the 2nd. The 3rd common digital nerve is located between and often distal to the 3rd and 4th metatarsal heads, plantar to the intermetatarsal ligament.

Signs/Symptoms

Intermetatarsal neuromas are more common in females, possibly due to shoe gear, and most common in the fourth to sixth decades of life. Pain is described as burning, cramping, or sharp and frequently radiates to the toes. Patients may also have pain radiating proximally and may notice numbness or tingling. Patients often have the sensation of walking on a wrinkle in their sock.

Pain is worse in shoes and upon dorsiflexion of MPJs (high heels). Pain is relieved by removing shoe and massaging affected area.

Lateral squeeze test—point tenderness upon palpation of the plantar aspect between the metatarsal heads while squeezing the metatarsal heads together

Mulder sign—silent palpable click that the patient feels while walking and can often be reproduced while performing the lateral squeeze test

Sullivan sign—toes adjacent to affected IS splay apart on weight-bearing.

Treatment

Modification of shoe gear
Orthotics, strapping, padding
Corticosteroid injections
Oral anti-inflammatory agents
Cold therapy, stretching, and other PT modalities
Surgery: neurectomy, EDIN, transection of the intermetatarsal ligament
A stump neuroma can be a complication from a neurectomy surgery for a Morton neuroma. A stump neuroma occurs when the proximal nerve segment following a neurectomy attempts to regenerate and develops a bulb-shaped stump. Treatment for a stump neuroma is much the same as for a Morton neuroma.

Joplin Neuroma

A benign enlargement of the medial plantar digital proper nerve located on the plantar medial aspect of the 1st MPJ of the hallux. Signs and symptoms are similar to those of other distal focal neuropathies and include paresthesia and burning with pain at the point if compression or entrapment.

The cause is usually biomechanical (excessive pronation, hallux limitus). Treatments for a Joplin neuroma include off-weighting the nerve, orthotics, injections, NSAIDs, and neurectomy.

Tarsal Tunnel Syndrome

Entrapment or compression neuropathy within the tarsal tunnel beneath the flexor retinaculum (laciniate ligament). The tibial nerve divides into three branches beneath the flexor retinaculum: medial plantar nerve, lateral plantar nerve, and the medial calcaneal nerve. Tarsal tunnel syndrome is analogous to carpal tunnel syndrome in the wrist.

Tarsal Tunnel Borders

Flexor retinaculum (laciniate ligament)—medially and posteriorly

Calcaneus and posterior aspect of talus—laterally

Distal tibia and medial malleolus—anteriorly

Cause

Trauma (fracture, sprain, dislocation)
Inflammatory conditions (RA, tendonitis, synovitis, diabetes)
Space-occupying lesions (ganglion, varicosities, lipoma, neurilemoma, edema)
Biomechanical (excessive pronation results in stretching of the tibial nerve)

Signs/Symptoms

Numbness, pins and needles, burning, or shooting pains over the entire plantar foot may occur. Symptoms are usually exacerbated by activity such as prolonged weight-bearing, walking, or running. Forced eversion of the foot may produce symptoms because this motion essentially stretches the nerve and compresses the content of the tarsal tunnel. Intrinsic muscle atrophy
with hammertoe formation is a late manifestation. A positive Tinel sign, Valleix sign, or Turks test may also be present.

Surgical Treatment

Surgical treatment involves a longitudinal incision of the flexor retinaculum. Space-occupying lesions such as varicosities, cysts, or masses are removed. The tibial nerve is mobilized. Care must be taken not to damage the medial calcaneal branch of the tibial nerve as it penetrates the flexor retinaculum to provide sensory innervation to the medial heel. A tourniquet may or may not be used, however, with a vascular etiology such as varicosities; a tourniquet may hide the pathology. The flexor retinaculum is not sutured back after surgery to prevent constriction of the nerve.

MISCELLANEOUS NEUROLOGIC CONDITIONS

Multiple Sclerosis

A chronic inflammatory disease in which the immune system attacks the myelin sheath of the nerves in the CNS. Myelin damage disrupts communication between the brain and the body. Multiple sclerosis is progressive, and clinical course is highly variable and unpredictable. Generally, there is a relapsing and remitting presentation. MS can present with almost any neurologic symptom with weakness, tingling, numbness, and blurred vision being the most common. Females are twice as likely to develop MS, and first symptoms tend to occur between ages 20 and 40. Excessive heat may accentuate symptoms, avoid hot baths and Jacuzzis. The cause is unknown but thought to be autoimmune possibly brought on by a virus or genetic defect.

Amyotrophic Lateral Sclerosis (ALS, Lou Gehrig DZ)

A devastating progressive degenerative disease of both UMNs and
LMNs results in muscle weakness and atrophy throughout the body. Mental status is usually preserved. Males are twice as likely to develop the condition, and onset usually occurs when patients are in their 40s. Death usually occurs within 3 to 5 years of onset, and respiratory failure is the most common cause of death.

Signs/Symptoms

Initially symptoms are subtle, frequent tripping or stumbling difficulty with manual dexterity, weight loss, and slurred speech. Later symptoms include difficulty swallowing (dysphagia), difficulty speaking (dysarthria), spasticity, positive Babinski sign, and hyperreflexia. Eventually, patients become completely immobile with significant muscle atrophy, contractions, and wasting. Because ALS can result in both upper and lower motor neuron lesions, symptoms can vary depending on which nerves are damaged.

UMN Lesion	LMN Lesion
(+) Babinski	Pathologic reflexes absent
(+) Clonus	(-) Clonus
Loss of superficial reflexes	Superficial reflexes unaltered
No atrophy	Atrophy (wasting)
Hyperreflexia of deep reflexes	Hyporeflexia of deep reflexes
Spasticity	Hypotonicity
Spastic paralysis	Flaccid paralysis
No fasciculations	Fasciculations

Cause

Genetic disorder

Guillain-Barré Syndrome (Landry Paralysis)

An acutely progressive but self-limiting, acquired, inflammatory, demyelinating polyneuropathy resulting in rapid weakness and paralysis. The weakness spreads within several days and, in some cases, may cause life-threatening breathing difficulty. Most commonly affects those between 30 and 50 years of age. Spontaneous recovery begins 1 to 3 weeks after onset, and complete recovery usually takes place within 3 to 6 months; in more severe forms, permanent residual paralysis may occur, most notably foot drop.

Cause

Autoimmune disorder where the immune system attacks the nerves

There is often a precipitating factor such as a respiratory or digestive tract infection or a viral infection. Rarely, vaccination or recent surgery can trigger an attack.

Charcot-Marie-Tooth Disease (CMT, Peroneal Muscular Atrophy)

A group of hereditary disorders that cause damage to the peripheral nervous system. The main symptoms are slow progressive distal to proximal muscle weakness and atrophy. It initially affects the lower extremity and finally progresses to the upper limbs. Foot drop is often the first sign of the disease. CMT is the most common hereditary neuromuscular disorder and was named after the three physicians who first recognized the disease. There may or may not be sensory changes including peripheral neuropathy, but these are less severe than motor function deficit. Symptoms usually develop in adolescence or early adulthood, but this condition can develop in midlife too. CMT is not considered fatal, and people with most forms have a normal life expectancy.

Cause

Hereditary

Signs/Symptoms

Symptoms usually begin in the feet and legs with pes cavus, drop foot (slapping gait), and hammertoes.

CMT affects the peroneus brevis while sparing the peroneus longus; this accounts for the pes cavus deformity.

The order of muscle involvement is:

1. Plantar intrinsics

2. Tibialis anterior

3. EDL

4. EHL

5. Peroneus brevis

Loss of muscle bulk in the legs, giving the legs the classic “inverted champagne bottle” or “stork leg” appearance due to atrophy

Unsteady gait, tending to trip easily

Stocking-glove sensory loss

Decrease ankle DTRs

Charcot Joint (Charcot Arthropathy)

A destructive arthropathy resulting from peripheral neuropathy and
increased bone blood flow from reflex vasodilation. A Charcot foot results in fractures and dislocations of bones with minimal or no known trauma. Initial symptoms include swelling, redness, and increased warmth of the foot or ankle. Later, as fractures and dislocations occur, there may be significant deformity of the foot, resulting in equinus and collapse of the midfoot. Patients become weight-bearing in the arch of the foot (rocker bottom foot), and plantar ulcers develop. The midfoot is the most commonly affected area, followed by the rearfoot, ankle, heel, and forefoot.

Stages

Stage 1 (acute): Red, hot, swollen foot. Radiographically there may be signs of early bony fragmentation and joint dislocation. It is very important to off weight the foot as soon as these symptoms develop.

Stage 2 (coalescence): Redness and warmth while still present are decreased. Radiographs show early signs of bony healing.

Stage 3 (consolidation): Redness, swelling, and warmth resolve. Radiographically bones stabilize, round off, and fuse in place. Severe deformity may be present based on the patient’s weight-bearing status in stages 1 and 2.

Causes

Any condition causing neuropathy can result in a Charcot foot, most commonly diabetes.

Friedreich Ataxia

An inherited disease that results in spinal cord and peripheral nerve degeneration and to become thinner. Most patients with Friedreich ataxia also develop scoliosis and require back surgery. The condition results in awkward unsteady movements, ataxia, and decreased sensory function, but does not affect cognitive function. Friedreich ataxia also affects the heart by causing hypertrophic cardiomyopathy, leading to decrease in the heart’s pumping capacity. Symptoms typically begin between 5 and 15 years of age. Patients are usually confined to a wheelchair within 10 to 20 years after onset.

CRPS (Complex Regional Pain Syndrome)

Formerly known as RSD (Reflex Sympathetic Dystrophy). A progressive disease of the autonomic nervous system, more specifically the sympathetic nervous system. The disease is characterized by persistent severe burning pain associated with trophic and vasomotor changes. Trophic changes may include skin and bone
atrophy (Sudeck atrophy), hair loss, and joint contractures. Autonomic changes include sweating or vasomotor changes. Seventy-five percent of those affected are females. CRPS usually occurs in patients who are in their 30s and 40s. It usually occurs in one of the four extremities. The pain is initially localized to the site of injury or the distribution of the affected nerve, but with time, it spreads to involve the entire extremity. Onset can range from several days to years.

There are two types of CRPS:

CRPS type I (RSD)

Induced by soft tissue or bone injury. Usually caused by minor nerve injury (sprain, fracture, infection, fall). Sometimes, the nerve injury cannot immediately be identified.

CRPS Type II (causalgia)

Induced by nerve injury

Stages

Stage 1 (Acute, 1 to 3 Months)

Constant burning pain, allodynia, hyperalgesia, hyperesthesia, hyperpathia, localized edema, joint stiffness, limitation of motion. Initially, the skin is warm, red, and dry, but near the end of this stage, it becomes cyanotic, cold, and sweaty. Bone scans with technetium (99 mTC) show increased uptake by the small joints. Radiographs are usually normal; changes take 5 to 6 weeks to develop.

Stage 2 (Dystrophic, 3 to 6 Months)

Continuous burning, aching pain, allodynia, hyperalgesia, hyperpathia, indurated edema. The skin takes on a cool, pale, discolored, and frequently mottled or cyanotic appearance. Dystrophic changes occur, hair growth is decreased, and nails are brittle, cracked, and ridged. Radiographs may show spotty diffuse osteopenia (Sudeck atrophy). Joints become thickened and contracted, and muscle wasting may be present. This stage is still capable of improvement.

Stage 3 (Atrophic, Greater than 6 Months)

Pain in entire limb with muscle wasting and limited movement due to contractures and ankyloses. Radiographs show marked spotty or diffuse periarticular demineralization. Prognosis at this stage is poor.

Diagnosis

Diagnosis is difficult by history and physical. Thermography may be helpful, decrease in temperature in either the early or late stages of the disease, possibly increased temperature localized around joints. Bone scans reveal diffuse increased uptake in the affected area using a three-phase technetium bone scan. Radiographs show spotty or diffuse osteopenia (Sudeck atrophy). Radiologic findings can take several months to develop. Doppler may be helpful in evaluating vasomotor changes. Sympathetic blocks with relief of symptoms can aid diagnosis.

Treatment

Early diagnosis and treatment are crucial for a good prognosis. Prompt diagnosis and treatment can result in remission of symptoms and complete recovery.

Treatment may include medications such as steroids, drugs used for
peripheral neuropathy. Physical therapy is crucial, massage, ROM exercises, US, splinting, and contrast baths. Treatments that interfere with nerve transmission such as TENS, acupuncture, and sympathectomies are beneficial. Nerve blocks and psychotherapy are also used. Avoid surgery on these patients, if at all possible.

ELECTROMYOGRAPHY (EMG) AND NERVE CONDUCTION VELOCITY (NCV) STUDIES

Used for electrodiagnosis of neuromuscular disorders

EMG—Electromyography

Assesses the electrical activity generated by muscle fibers at rest and with activity

NCV—Nerve Conduction Velocity

Used to distinguish conditions involving the myelin sheath from those affecting the axon. They are also helpful in determining the distribution of a nerve lesion, including areas of focal nerve compression (tarsal tunnel). NCVs measure the latency of motor nerve conduction, which is the time from stimulation of a nerve to the evoked muscle response. The test is performed by stimulating one point on a nerve and measuring the time taken before the muscle responds. The test is then repeated at a second site closer to the muscle. By subtracting one time from the other, it is possible to determine the time taken for the impulse to cover the measurable distance between the two sites of stimulation. The result is a rate of meters per second (mps). Normal values vary but are almost always greater than 40 mps.

PERIPHERAL NEUROPATHY

The following chart was reproduced with permission from The Neuropathy Association; 60 E. 42nd St. Ste. 942, New York, NY 10165 Phone (800) 247-6968. The Neuropathy Association is a nonprofit, charitable, patient-based organization that provides support and education and promotes research into the cause and treatment of peripheral neuropathy.

Neuropathies

Immune-Mediated or Inflammatory Neuropathies

Neuropathy	Epidemiology Risk Factors	Clinical Features	Laboratory Features	Pathology/Pathophysiology	Treatment	Prognosis
Acute inflammation demyelinating polyneuropathy (AIDP; Guillain-Barré syndrome)	Rate 0.6-2.4/million/y follows infection, surgery, vaccination trauma, immune perturbation	Weakness, loss of reflexes, sometimes sensory symptoms, respiratory paralysis, or changes in blood pressure or pulses	Nerve conduction abnormalities, increase in CSF protein	Demyelination, inflammation	Supportive care, plasma exchange, IVIg	85% have functional recovery
Acute motor axonal neuropathy (AMAN)	Incidence not known, seasonal, Campylobacter jejuni infection proposed	Muscle weakness, sometimes respiratory paralysis	Abnormal EMG and motor conductions, increased CSF protein, sometimes associated with IgG anti-GMI antibodies	Motor axonal degeneration	Supportive care, IVIg	Variable, better recovery in younger patients
Acute motor and sensory axonal neuropathy (AMSAN)	Less common than AIDP, affects a wide range of ages	Weakness, sensory loss, pain, sometimes respiratory paralysis or change in blood pressure or pulse	Abnormal EMG and nerve conductions, increased CSF protein	Axonal degeneration and demyelination	Supportive care, plasma exchange, IVIg	Poor recovery
Miller Fisher syndrome (MFS)	Rare in pure form	Double vision, extraocular muscle weakness, ataxia, loss or reflexes	Nerve conductions may be abnormal, increased CSF protein, IgG anti-GQ1b antibodies	Degeneration of nerves to extraocular muscles	Same as above	Most recovery
Acute sensory neuropathy or ganglioneuritis	Rare	Sensory loss, pain, ataxia	Sensory nerve conduction abnormalities	Degeneration of sensory nerves or ganglia	Same as above	Variable
Acute autonomic neuropathy (pandysautonomia)	Rare	Bowel and bladder dysfunction, fluctuations in blood pressure and pulse, abnormal sweating	Nerve conductions may be abnormal	Degeneration of autonomic nerves or ganglia	Same as above	Variable
Chronic inflammatory demyelinating polyneuropathy (CIDP)	May be associated with preceding drug use, vaccination, infection, other autoimmune or collagen vascular disease, or monoclonal gammopathies	Progressive weakness, usually symmetric, relapsing, with sensory changes, absent reflexes. Predominant sensory form also occurs.	Abnormal nerve conductions, increased spinal fluid protein, nerve, biopsy exhibiting demyelination	Demyelination, inflammatory cells, increased CSF protein	Prednisone, IVIg, plasmapheresis, cytotoxic agents	Most can improve with therapy
Demyelinating neuropathy associated with anti-MAG antibodies	Incidence not known (1-5 per 100,000), IgM monoclonal gammopathy (>90%)	Progressive, sensory, or sensorimotor	Slowed nerve conductions, IgM anti-MAG antibodies	Demyelination, deposits of IgM and C′ on myelin sheaths, antibody mediated	Plasmapheresis, IVIg, chemotherapy	Can often improve or be arrested
Multifocal motor neuropathy	Incidence not known, sometimes associated with IgM monoclonal gammopathies	Progressive weakness, usually asymmetric	Abnormal EMG and motor nerve conductions or conduction blocks, frequently associated with IgM anti-GMI or rarely anti-GD1a ganglioside antibodies	Demyelination and axonal degeneration of motor nerves	IVIg, chemotherapy	Can often improve or be arrested
Chronic inflammatory sensory neuropathy associated with anti-nerve antibodies	Incidence not known, sometimes associated with IgM monoclonal gammopathies	Progressive sensory loss, ataxia, or pain	Abnormal sensory nerve conductions, associated with anti-sulfatide or GD1b antibodies	Degeneration of sensory nerves	Prednisone, IVIg, chemotherapy, pain therapy	Can often be arrested, sometimes improved
Ganglioneuritis or sensory neuronitis	Incidence not known, sometimes associated with Sjögren syndrome	Sensory loss, pain, ataxia may involve face and trunk	Abnormal sensory nerve conductions. Anti-SSA-La or SSB-Ro antibodies.	Inflammation of dorsal root ganglia	Prednisone,? IVIg, chemotherapy, pain therapy	Can sometimes improve or be arrested
Paraneoplastic sensory neuronopathy associated with anti-HU antibodies	Rare, usually associated with lung cancer	Progressive sensory loss in arms and legs, ataxia	Anti-HU antibodies, abnormal sensory nerve conductions	Inflammation and degeneration of dorsal root ganglia	Treatment of cancer, prednisone, IVIg	Poor, usually progressive and debilitating
Chronic inflammatory axonal polyneuropathy	Rare, incidence not known	Progressive sensory loss, pain, weakness	Abnormal EMG and nerve conductions	Axonal degeneration	Prednisone,? IVIg,? Plasmapheresis	Can often improve or be stabilized with therapy

Vasculitic Neuropathies

Neuropathy	Epidemiology Risk Factors	Clinical Features	Laboratory Features	Pathology/Pathophysiology	Treatment	Prognosis
Vasculitic neuropathy, nonsystemic	Five new cases per million per year	Weakness, sensory loss, and pain in isolated nerves (45%), overlapping nerves (40%), or symmetric neuropathy (15%)	Abnormal EMG and nerve conductions, nerve and muscle biopsy showing vasculitic changes	Vasculitis	Prednisone, cyclophosphamide, plasmapheresis	Most improve with therapy, but with residual deficits, may relapse
Vasculitis neuropathy associated with systemic disease	Incidence not known, may be associated with polyarteritis nodosa, Wegener granulomatosis Churg-Strauss syndrome, other collagen vascular diseases, cancer, hypersensitivity reaction, or with hepatitis B or C infection, HIV-1 or Lyme disease	Same as above, plus associated with systemic symptoms, including fever, weight loss, anorexia, arthralgia skin rash, or renal, lung, or gastrointestinal disease	Same as above, plus elevated ESR, anemia, ANA, ENA, cryoglobulins, P-ANCA, hepatitis B or C antibodies, or HIV-1 or Lyme serologies	Vasculitis	Prednisone, plasmapheresis cyclophosphamide, plus treatment for underlying systemic disease

Inflammatory Plexopathies

Neuropathy	Epidemiology Risk Factors	Clinical Features	Laboratory Features	Pathology/Pathophysiology	Treatment	Prognosis
Brachial plexitis	Usually sporadic, some familial predisposition, may follow vaccination, infection, IV drug use, or associated with connective tissue disease	Pain followed by weakness of shoulders and proximal arms. Hands sometimes affected. Variable sensory loss, usually asymmetric.	Abnormal EMG and nerve conductions	Inflammatory, presumed autoimmune	Prednisone for limited duration,? IVIg, pain therapy, physical therapy	Most recover, but recovery may be slow or incomplete
Lumbosacral plexitis	Incidence not known, sometimes associated with diabetes	Pain, followed by weakness of hips and upper legs, usually asymmetric	Abnormal EMG and nerve conductions	Inflammatory, presumed autoimmune	Same as above	Same as above

Sarcoid Neuropathy

Neuropathy	Epidemiology Risk Factors	Clinical Features	Laboratory Features	Pathology/Pathophysiology	Treatment	Prognosis
Sarcoid neuropathy	Rare, associated with systemic sarcoid	Progressive, often asymmetric or multifocal, can involve cranial nerves	Elevated ACE, adenopathy	Granulomas in peripheral nerves	Prednisone	Can often improve or be arrested

Diabetic Neuropathies

Neuropathy	Epidemiology Risk Factors	Clinical Features	Laboratory Features	Pathology/Pathophysiology	Treatment	Prognosis
Distal symmetric diabetic polyneuropathy	50% lifetime risk of developing neuropathy, 20% of these are symptomatic	Sensory loss and pain in the hands and feet, sometimes weakness	Hyperglycemia, abnormal nerve conductions	Axonal degeneration with demyelination, microangiopathy	Improved glycemic control, foot care, pain management, physical therapy	Slowly progressive
Autonomic neuropathy	Usually in type I diabetics, incidence not known	Gastroparesis, diarrhea, postural hypotension, impotence, lack of sweating	Abnormal autonomic tests	Microanglopathy, degeneration of autonomic nerves	Symptomatic treatment	Slowly progressive
Diabetic amyotrophy or lumbosacral plexopathy	Less than 1% of patients with diabetes	Pain and weakness in thighs, difficulty walking, may be asymmetric	Abnormal EMG and nerve conductions	Involvement of lumbosacral plexus, axonal degeneration	Pain therapy, physical therapy	Usually, but not always, improves spontaneously. May have residual deficits.
Mononeuritis or mononeuritis multiplex	Less than 1% of patients with diabetes	Weakness, pain, or sensory loss in one or several nerves or nerve roots. May affect cranial or truncal nerves as well as limbs.	Abnormal EMG and nerve conductions	Discreet infarcts in nerves secondary to vascular occlusions, demyelination secondary to compression	Pain therapy, physical therapy. Appropriate surgical decompression approaches for carpal tunnel syndrome.	Usually improves spontaneously. May have residual deficits.