• Auvi-Q is a new, user-friendly epinephrine injector. The auto-injector device has an audio message that verbally walks the patient through administration of the drug. This audio-prompter is built in to the injector as a single unit. This new device has proven useful in patients who otherwise are hesitant to use epinephrine.
• Sleep deprivation can lessen the immune response to vaccines, report researchers at UCLA. In a controlled study they found that restricting sleep to four hours per night for five days led to only a 50 percent response to vaccination. Take-home message: If your or your child are sleep-deprived put off getting your childhood or adult vaccines until you are well-rested.
A recent issue of the New England Journal of Medicine contained an excellent review article on the condition known as chronic pruritis – defined as an itch (either localized or generalized) that lasts longer than six weeks. The problem is more common in women than in men and more common in Asians than other races.
The authors of the review article point out that chronic itch can be as debilitating as chronic pain,
leading to changes in sleep patterns and mood disturbances including anxiety and depression.
The sense of itch is carried on unmyelinated C fibers which overlap with the fibers carrying pain. Over-stimulation of the brain areas receiving these nerves can lead the brain to overreact to noxious stimuli that would otherwise normally inhibit itch, such as scratching or heat/cold exposure. This brain overreaction can also lead to curious symptoms, such as having intense itching associated with undressing.
There are four primary sources of chronic pruritis:
1. Inflammatory skin conditions
2. Systemic diseases
3. Neuropathic disorders. Believe it or not, these can’t be distinguished by the presence or absence of rash because most individuals with chronic pruritis end up with a rash due to trauma to the skin from scratching.
4. Psychiatric conditions.
The most common skin conditions leading to chronic itch are eczema, psoriasis, dry skin, scabies, contact dermatitis, Lichen planus and insect bites. These are best diagnosed by the patient’s history, the appearance of the skin and perhaps, with a skin biopsy.
The most common systemic diseases to cause itch are chronic kidney disease, liver disease, Hodgkins disease, polycythemia, HIV infection and hyperthyroidism. These conditions are best identified by the patient’s history, examination and lab evaluation.
The most common neuropathic causes are brachioradial pruritis (previously discussed in this newsletter), notalgia parasthetica and post-herpetic itch. In all these cases there is a peripheral nerve that is injured or irritated, leading to the itch signal being sent to the brain.
The most common psychogenic causes are OCD (obsessive compulsive disorder), delusions of parasitosis and substance abuse.
Obviously, the treatment is going to vary greatly depending on the cause of the itch. However, even with an accurate diagnosis the itch may be resistant to treatment. In most cases, keeping the skin moist and hydrated is helpful.
Since the C-Fibers are histamine-activated nerves, the use of sedating antihistamines is also helpful. Because of the brain over-stimulation scenario, anticonvulsants and antidepressants have also proven useful.
Finally, because of the overlap of itch and pain fibers, mu-opiod antagonists have often been of help.
Dear Dr. K: My aunt has Ramsay Hunt syndrome and her doctor said it was a second bout of chicken pox. Is that true?
The answer to your question is yes and no. In the strictest sense the answer is no, because your aunt doesn’t have generalized chicken pox, but rather a very localized rash. The answer is yes because, in general terms, Ramsay Hunt is a special form of shingles which is a reactivation of the dormant chicken pox virus (Varicella zoster).
Shingles gets its name because the Varicella virus breaks out in the distribution or dermatone of a single nerve affecting a localized “shingle” of our skin covering.
Ramsay Hunt is an interesting condition because it has unusual neurologic symptoms, in addition to the typical blistering rash. Typically, the patient’s first symptom is severe unilateral ear pain (before any rash). Other common symptoms include facial weakness or paralysis on the side of the ear pain, and ear problems including tinnitus, hearing loss and vertigo.
The shingles rash appears on the ear pinna, the side of the face and side of the neck under the ear.
This condition is preventable with the Zostavax (shingles) vaccine, and can be treated with an oral antiviral and corticosteroids. The earlier this therapy is started, the better.
So, thanks for your question as it may lead to greater awareness of this very unpleasant condition – and to more early diagnoses.
Recent research has discovered that narcolepsy is a genetically controlled autoimmune disease. Individuals with the gene HLA-DRz/DQI have a very high risk that their immune system will attack a
part of the brain called the hypothalamus. It is in this brain region that an important neuropeptide called hypocretin is made.
Hypocretin is a very important neuropeptide for maintaining alert wakefulness. If the cells in the
hypothalamus that produce it are damaged or destroyed, narcolepsy occurs.
This condition is characterized by a tendency to fall asleep inappropriately during the day. Other unusual symptoms can also occur, such as cataplexy (sudden loss of muscle tone); sleep paralysis (awakening to find your body paralyzed except for breathing); hypnogogic hallucinations (seeing hallucinations just as you’re falling asleep), and what may seem like absent-minded behaviors (such as driving past your exit on the interstate or putting clothing in the refrigerator).
The lack of alerting effects of hypocretin allow non-REM sleep and/or REM sleep to intrude into wakeful times; hence, the unusual symptoms.
Treating this condition can be very helpful but – as in all medical illnesses – it requires an accurate diagnosis. This is probably best accomplished by a sleep doctor. Unlike sleep apnea, it doesn’t respond to CPAP treatment. The two main treatments are daytime stimulants and methylphenidate, and REMsuppressants such as protriptyline.