Clinical Variants of Pruritus

Aquagenic Pruritus

The person with aquagenic pruritus experiences intense itching only after exposure to water.

Notalgia Paresthetica

Notalgia paresthetica is a common condition seen most often in middle-aged and elderly patients.
It is thought to represent a sensory neuropathy that may be caused by nerve impingement from spinal arthritis.
Notalgia paresthetica most often presents with a localized, very focal, unilateral area of recurrent itching that characteristically occurs on the lower or mid-scapula. The postinflammatory hyperpigmentation that sometimes results from the chronic rubbing and scratching reveals the diagnosis (Fig. 24.5).
Treatment is often futile. Capsaicin (Zostrix) cream, which depletes nerve endings of their chemical transmitters, applied 3 to 5 times daily can improve symptoms.
Topical corticosteroids, topical anesthetics (e.g., pramoxine, lidocaine), gabapentin, and acupuncture have all been tried with variable results.
There have been case reports of successful treatment with botulinum toxin type A for this condition.

Brachioradial pruritus (BRP) is an intense itching sensation of the arm, usually between the shoulder and elbow of one or both arms.
There is ongoing debate regarding whether BRP is caused by a nerve entrapment in the cervical spine or a prolonged exposure to sunlight, because the outer, sun-exposed aspects of the arms are most often affected.
Measures to treat BRP include the following:
- Sun protection—wearing clothing with long sleeves is more effective than use of sunscreens alone
- Capsaicin (Zostrix) cream
- Ice packs
- Amitriptyline tablets at bedtime
- Anticonvulsant agents, including gabapentin (Neurontin) 300 mg three times daily
- Electrical cutaneous nerve field stimulation

Pruritus from Systemic Disease

Internal disorders such as chronic renal or liver failure can result in generalized pruritus.

Management

For Renal Disease

Renal pruritus occurs most often in those receiving hemodialysis.
Ultraviolet B (UVB) therapy is often effective. Narrow-band UVB is particularly effective.
Oral ingestion of activated charcoal may be helpful. It is inexpensive and generally well tolerated; therefore, it is considered a reasonable treatment when UV therapy has failed.
Successful kidney transplantation is the only definitive treatment for chronic renal pruritus.

For Liver Disease

Cholestyramine (Questran), a bile acid sequestrant, can be used to treat the pruritus that often occurs during liver failure because of the liver's inability to eliminate bile.
Cholestyramine binds bile in the gastrointestinal tract to prevent its reabsorption.
Pruritus associated with obstructive malignancy of the biliary tract (e.g., primary sclerosing cholangitis) may be relieved by placing a stent to relieve the obstruction.

For Hypothyroidism

The pruritus of hypothyroidism is primarily secondary to xerosis and should be treated with emollients and thyroid hormone replacement.

For Hyperthyroidism

Pruritus secondary to hyperthyroidism generally improves with correction of thyroid function.

For Hodgkin Disease

Pruritus caused by lymphoma may precede the diagnosis.
Systemic corticosteroids with palliative chemotherapy in late-stage Hodgkin disease often provide relief.

Outline
Aquagenic Pruritus
Notalgia Paresthetica
Brachioradial Pruritus
Pruritus from Systemic Disease