Post exposure prophylaxis for Varicella?

The author of this blog is currently in day 7 of illness, suffering from a moderate form of varicella. In spite of starting acyclovir (thanks to vigilant and quick-acting wife) on the day of eruptions, the disease process was not halted and vesicles are florid. While we are taking precautions against pneumonia, encephalitis, and other adult-onset associated complications, it is my 2yr old that I agonise about.

He is an 'exposed' individual. Varicella infections in children are mild and rarely complicated. Being an otolaryngologist, however, we know that Ramsay-Hunt (herpes zoster oticus; i.e. reactivation of virus in facial nerve) syndrome causes debilitating facial palsy - sometimes irreversible. Shingles is painful, too. My question is, should I bother vaccinating him now? He was planned for his jab next week, but now that he is exposed, shouldn't I just wait and see if he develops the infection which would obviate vaccination altogether?

Well, this is where the evidence is really useful:

According to the Cochrane review of randomized trials evaluating varicella vaccine in children and adults; from 3 trials with 110 healthy siblings of household contacts where they received post-exposure prophylaxis (PEP) within 3 days of exposure or not at all:
- varicella developed in 18% (PEP) vs. 78% (no PEP) (p < 0.05)
- moderate to severe varicella developed in 2% (PEP) vs. 76% (no PEP) (p < 0.05)
- PEP group who developed varicella had mild disease (< 50 skin lesions)
- no trials reported on adverse events following immunization

Also, for all my healthcare worker friends out there, don't be a hero (or a chicken, depending why you're delaying.) Get yourself jabbed now! Varicella vaccine is recommended for those who have never had chickenpox and are seronegative for varicella antibodies. The caveat (or bonus) is 1-5% adult develop varicella-like rashes that shed the virus and should be removed from patient contact (perfect excuse for holiday, no?) [Am Fam Physician 1997 Dec;56(9):2291]

Unilateral hearing loss: To MR or not to MR?

The occasional case of unilateral hearing loss sometimes poses a dilemma. Should we order MRIs to rule out acoustic neuroma for every case of unexplained unilateral SNHL when the incidence is only 1 in 100,000?

Perhaps our suspicion index can be guided by the symptom profile of acoustic neuroma where there is:
93.4% hearing impairment
75.5% tinnitus
40.6% vertigo
38.8% unsteadiness

Hearing loss can be sudden (12-47%) or insidious

Ho & Kveton, 2002, recommended a protocol for investigation:
- for patients with limited symptoms (isolated vertigo, historically explained unilateral hearing loss or tinnitus, or symmetrical hearing loss; estimated risk of acoustic neuroma < 5%): ABR as initial test and MRI if abnormal ABR
- for patients with intermediate symptoms (sudden sensorineural hearing loss or unexplained persistent unilateral tinnitus; estimated risk of acoustic neuroma 5-30%): MRI as initial test
- for high-risk patients with combination of unilateral asymmetric sensorineural hearing loss, tinnitus and decreased speech discrimination (estimated risk of acoustic neuroma > 30%): MRI with gadolinium initially and periodic ABR testing if negative MRI


On the other hand, it is worth remembering that tumor growth is on average 1-2.3 mm/year and less than 30% grow > 2 mm/year so that serial MRIs are hardly helpful and may not require any intervention in the elderly.

References
Arch Otolaryngol Head Neck Surg 2004 Feb;130(2):216
Neurosurgery 2006 Jul;59(1):67
J Laryngol Otol 1994 Feb;108(2):116
Am J Otolaryngol 1999 May-Jun;20(3):157
Neurosurgery 1997 Jan;40(1):1
Otolaryngol Clin North Am. 2002 Apr;35(2):393-404, viii

HIgh frequency hearing loss from low frequency noise

It has long been believed that the spectrum of hearing loss closely matches that of the presenting noise. An antiquated study by Mill et al showed that this is not always true.

Human subjects were exposed to an octave-band noise for 24 hours. Temporary threshold shifts increased for the first eight hours of exposure and then were asymptotic. While threshold shifts were largest at about one-half octave above the center frequency of the noise, a second maximum was observed at higher test frequencies. The exact frequency of this second maximum decreased from 7.0 kHz, for a noise centered at 2.0 kHz, to 5.5 kHz for a noise centered at 0.5 kHz. This result could be caused by the travelling wave pattern along the cochlear partition or to the production of distortion products.

PubMed

New centre for deafness research

'A new centre is to open in London in the new year, bringing together the previously disparate fields of research into deafness and communication.

The Deafness, Cognition and Language Research Centre (DCAL) will be based at University College London and will be funded by a 4.5m grant from the Economic and Social Research Council (ESRC), it was announced yesterday.

The aim of the centre is to create "a world-class hub of excellence" that will connect research into neuroscience and linguistics to issues affecting deaf individuals in their communities. It will also seek to challenge the perceptions of deafness and study sign language and communication techniques. All the centre's researchers will be expected to become fluent in British Sign Language.'

EducationGuardian.co.uk

Medical management of middle ear disease in children less than 2 years of age with sensorineural hearing loss

'Pneumatic otoscopy should be used to diagnose middle ear effusion. Clearance of OME may be prolonged in children with craniofacial abnormalities. Antibiotics provide a small short-term increase in the resolution of OME and may be warranted in children with coexisting SNHL and OME for 4 to 6 weeks. If OME persists for 8 to 12 weeks, bilateral myringotomy and tube placement (BM&T) with short-term tubes will improve hearing and help resolve OME. AOM in children less than 2 years of age should be treated with a 10-day course of antibiotics. Prophylactic antibiotics may be useful in avoiding tube placement in children less than 2 years of age with recurrent AOM. BM&T with short-term tubes are recommended if recurrent AOM persists. Pneumococcal vaccination can decrease episodes of AOM by 6 to 7%.'

Above are the recommendations based on a meta-analytic study by Westerberg BD, et al. in J Otolaryngol. 2005 Aug;34 Suppl 2:S64-9.

Gene Therapy for Deafness

By Roger Highfield
American scientists have found that the transplant of a specific gene permits the growth of new hair cells in the inner ear.. The technique, which one day could help millions of people worldwide, was described yesterday by Dr Yehoash Raphael of the Kresge Hearing Research Institute, University of Michigan, in the journal Nature Medicine.
Read the FULL ARTICLE

Cure for sensorineural deafness?

Researchers in the US have for the first time restored hearing in deaf mammals - a feat that represents a major step toward treating people with acquired hearing loss.

By inserting a corrective gene with a virus, the team at the University of Michigan Medical School induced the formation of cochlear hair cells - the key intermediaries in converting sound waves into electrical impulses - in the ears of artificially deafened adult guinea pigs, according to the Los Angeles Times.

Read the FULL ARTICLE

Brain gene for Presbycusis

from Health India
A new study conducted by researchers at University of Rochester Medical Center suggests that a "feedback" problem in the brain diminishes our ability to hear.
"Traditionally, scientists studying hearing problems started looking at the ear. But we are finding patients with normal ears who still have trouble understanding a conversation. There are many people who have good inner ears who just don't hear well. That's because their brains are aging." lead researcher, Robert D. Frisina was quoted as saying.
Read the FULL ARTICLE

Insect Ears?

Many leave their hearing aids at home, by Mary Duenwald, NEW YORK TIMES

'In the pipeline are hearing aids that mimic the hearing apparatus of a kind of parasitic fly, Ormia ochracea, which has a keen sense of where sounds come from.

This insect's ears are connected by a platelike structure that senses both vibrations and pressure in such a way as to act like a tiny directional microphone, said Lynn Luethke, an audiologist and neurologist at the National Institute on Deafness and Other Communication Disorders in Bethesda, Md.

Hearing aids patterned after the fly's ear are expected to be ready in the next three to six years, Luethke said.'

How I straightened out my dizzy BPPV world

from The Republican
In writing this column, I run the risk of being charged with practicing medicine without a license. But if what I have to share helps just one person, I'm willing to take the chance. I'm going to write about BPPV, the acronym for benign paroxysmal positional vertigo. It's a dizziness that is caused by infinitesimal granules of debris that have the formal name of "otoconia," and are crystals of calcium carbonate, which come from a spot in one's ear called the utricle.