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MCAS: Effects on eyes, ears, nose and mouth

MCAS patients suffer a variety of symptoms in systems localized to the head, often without well characterized explanations.  Eye, ear, sinus, nasal and mouth symptoms are often documented.
Generic irritation of the eyes, including dry eyes and/or itchy eyes, are the most common ophthalmologic complaint.  Excessive tearing is also common.  Like many other symptoms, the tearing can be occasional or chronic.  Redness, irritation of the sclera (the white part of the eye), the eye lid, and conjunctivitis can all affect one or both eyes.  Tremors and tics of the lid are sometimes found.  When particularly bothersome, patients sometimes seek treatment with botulinum toxin (Botox).  This treatment is at first successful, but the issue later resurfaces.
Difficulty in focusing in both eyes is particularly common when suffering other MCAS symptoms.  Despite seeking ophthalmologic explanations for these symptoms, most patients have no obvious cause of their inflammation.  32% of MCAS patients report eye issues. 
Symptoms affecting both anatomy and function of the ears are not atypical.  Irritation of the outer ear is unusual, but middle ear irritation, resembling an infection, is extremely common.  These “infections” often occur frequently and are resistant to antibiotic treatment because they are, in fact, the result of sterile inflammation. 
Hearing abnormalities are often found in MCAS patients.  They include hearing loss, ringing of the ears, and sensitivity to sound.  This is thought to be from sclerosis of the innter ear bones or tympanic membrane, which has been known to occur coincidentally with mast cell disease since the 1960’s.  Deterioration of the canal hairs and auditory nerve is also suspected in some patients.  Tinnitus is likely from mediator release causing overstimulation of the hair cells and auditory nerve fibers.  The most common finding by audiologists is sensorineural hearing loss of unclear origin.
Mast cells are densely concentrated in the cavities and passages of sinuses and in the nose.  Congestion, inflammation, ulceration, sores and pain are all common.  MCAS patients often have a heightened sense of smell with systemic reactions possible from an offending scent.  Unprovoked nose bleeds sometimes occur, which is thought to be from increased local concentration of heparin.
Pain in the mouth and lips is a frequent complaint.  Like so many other MCAS symptoms, it can be focal or diffuse, mild or disabling.  It is often found with leukoplakia, but yeast infection is not found.  Distorted sense of taste, especially where things often taste of metal, is common.  Ulcerations and sores often present.  While on preliminary examination they resemble herpes sores, they almost never are in MCAS patients. 
MCAS is associated with burning mouth syndrome, which is exactly what it sounds like.  The mucosa is normal on biopsy.  Mast cell mediator therapy can relieve pain, sometimes very quickly. 
Evidence of angioedema is often seen in the mucosa of the cheeks, tongue and lips.  Patients often undergo evaluation for hereditary angioedema.  While they are sometimes found to have decreased levels of C1 esterase antigen or function, it is not low enough to account for the angioedema.  This finding is often a red herring. 
Dental decay, often despite excellent dental hygiene, is being reported with increasing frequency.  It can be a lifelong issue or sudden onset.   There are several reasons suggested for this, but none definitive. 

Afrin, Lawrence B. Presentation, diagnosis and management of mast cell activation syndrome.  2013.  Mast cells.