This has been attributed to the fact that excitation due to vibration of the basilar membrane spreads upwards from the apical regions of the basilar membrane, more than excitation spreads downwards from higher frequency basal regions of the cochlea. This pattern of the spread of excitation is similar to the ‘upward spread of masking’ phenomenon. If the tone is sufficiently loud to produce enough excitation at the normally functioning area of the cochlea, so that it is above that areas threshold. The tone will be detected, due to off-frequency listening which results in a misleading threshold.To help to overcome the issue of PTA producing inaccurate thresholds within dead regions, masking of the area beyond the dead region that is being stimulated can be used. This means that the threshold of the responding area is sufficiently raised, so that it cannot detect the spread of excitation from the tone. This technique has led to the suggestion that a low frequency dead region may be related to a loss of 40-50 dB. However, as one of the aims of PTA is to determine whether or not there is a dead region, it may be difficult to assess which frequencies to mask without the use of other tests.Based on research it has been suggested that a low frequency dead region may produce a relatively flat loss, or a very gradually sloping loss towards the higher frequencies. As the dead region will be less detectable due to the upward spread of excitation.
Adapalene/benzoyl peroxide, sold under the brand name Epiduo among others, is a fixed-dose combination medication for the treatment of severe acne vulgaris. It consists of a combination of adapalene and benzoyl peroxide in a topical gel formulation. Medical uses
Adapalene/benzoyl peroxide is indicated for the topical treatment of acne vulgaris. Side effects
Commonly reported side effects include the following:
Skin redness
Scaling
Dry skin
Contact dermatitis
Skin irritation
Stinging
Burning

Research
Meta-analysis of clinical trials has shown this combined therapy to be more effective than either of its ingredients by themselves.The use of adapalene/benzoyl peroxide in combination with oral antibiotics (lymecycline) has been studied; the combination was well tolerated and showed an improved success rate compared to those receiving only antibiotics (47.6% vs. 33.7%, P = 0.002). References
External links
"Adapalene mixture with benzoyl peroxide". Drug Information Portal. U.S. National Library of Medicine.