The prognosis is affected by early age onset, a higher number of meningiomas and schwannomas and having a decrease in mutation.An early diagnosis is the best way to ensure improvement in management. Although, even with an early diagnosis, some patients still die very young.Meningiomas and schwannomas occur in around half of patients with NF2. Meningiomas are tumors that are both intracranial and intraspinal. Schwannomas are tumors that are often centered on the internal auditory canal. Patients with NF2 who have meningiomas have a higher risk of mortality, and the treatment can be very challenging. Individuals who develop schwannomas frequently develop hearing loss and deafness. These individuals may also develop tinnitus after being presented with unilateral hearing loss. The first symptom that individuals may encounter is dizziness or imbalance.Truncating mutations lead to smaller and non-functional protein products. Studies have shown that missense mutations and large deletions can both cause predominantly mild phenotypes. Phenotype is more variable in patients with splice-site mutations, and a milder disease in patients with mutations in exons 9–15. Patients with a missense mutation have a greater survival rate than nonsense and frameshift mutations. Prevalence
Incidence of the condition is about 1 in 60,000. References
Further reading
Evans, D. Gareth (1993). "Neurofibromatosis 2". GeneReviews. University of Washington, Seattle. PMID 20301380. Retrieved 30 May 2017. == External links ==
Patients may have apparent enophthalmos (affected eye looks to be slightly sunken in) but this is not always the case. The ptosis from inactivation of the superior tarsal muscle causes the eye to appear sunken in, but when actually measured, enophthalmos is not present. The phenomenon of enophthalmos is seen in Horners syndrome in cats, rats, and dogs.Sometimes there is flushing on the affected side of the face due to dilation of blood vessels under the skin. The pupils light reflex is maintained as this is controlled via the parasympathetic nervous system.In children, Horners syndrome sometimes leads to heterochromia, a difference in eye color between the two eyes. This happens because a lack of sympathetic stimulation in childhood interferes with melanin pigmentation of the melanocytes in the superficial stroma of the iris.In veterinary medicine, signs can include partial closure of the third eyelid, or nictitating membrane. Causes
Horners syndrome is usually acquired as a result of disease, but may also be congenital (inborn, associated with heterochromatic iris) or iatrogenic (caused by medical treatment). In rare cases, Horners syndrome may be the result of repeated, minor head trauma, such as being hit with a soccer ball.