Norrie syndrome is a serious early childhood eye development disorder in boys. This is characterized by degenerative and proliferative changes in the neuroretina and can lead to blindness very early on. With a few exceptions, Norrie syndrome only occurs in males. An occurrence frequency of 1:100,000 is assumed.
What is Norrie Syndrome?
Norrie syndrome is a severe eye development disorder that results in congenital blindness. Almost only boys or men are affected by the disease. In addition to blindness, which can occur very early, about half of the patients also show progressive mental impairment. See aviationopedia for Hematocolpos Explanations.
These include decreased intelligence and behavioral problems. Around 30 percent of those affected develop deafness in the second decade of life. Additional problems include retinal detachment, progressive opacities of the lens, vitreous body, and cornea, iris atrophy, and bulb atrophy. These consequences usually appear in the first ten years after birth.
The hereditary disease, Norrie syndrome, is caused by a so-called gene mutation of the X chromosomes. It is inherited that the development of both eyes is reduced, which eventually leads to blindness. Usually, this condition only affects men. Women with one mutated gene copy are typically healthy, but statistics show they have a 50 percent risk of passing the disease on to their children.
Symptoms, Ailments & Signs
The first symptom seen in Norrie syndrome is usually a whitish-yellow, cloudy pupillary reflex on both sides (leucocoria). Almost all patients suffering from Norrie syndrome are blind from birth. This is triggered by retrolental, vascularized membranes.
This is a retina that is partially or completely detached from the back of the eye. From this, an undifferentiated, growing, vascularized tissue has formed.
Therefore, the pseudotumor of the retina (pseudoglioma) is often spoken of. In rare cases, a perception of light persists for a few years. In these affected people, it is usually observed that the retina detaches from the back of the eye with a delay. As the disease progresses, the entire eyeball usually shrinks (atrophy). Some people also develop glaucoma and bleeding into the retina and vitreous.
When the sufferers are 10 to 20 years old, there is usually also progressive hearing loss, which initially affects the high frequencies. Between the ages of 20 and 30, they are usually hard of hearing on both sides. Half of the patients also show cognitive limitations or behavioral problems.
Epileptic seizures have also been described in connection with Norrie syndrome. Furthermore, venous insufficiency, especially in the legs, was reported by some of those affected.
Diagnosis & course of disease
Norrie Syndrome requires close examination as some other diseases show a close resemblance and therefore it can easily be confused. These include, for example, retinoblastoma, persistent hyperplastic primary vitreus, primary retinal dysplasia, retinopathy of prematurity, Coats’ disease, osteoporosis pseudoglioma syndrome, X-linked juvenile retinoschisis and, in particular, familial exudative vitreoretinopathy.
Consequently, genetic testing is a prerequisite for making a clear diagnosis. Norrie syndrome can be diagnosed prenatally due to the prenatal diagnosis. Clinical genetic tests enable a familial risk assessment. Disease -causing mutations can be determined in almost all male cases by direct sequencing.
If the suspicion of Norrie syndrome cannot be confirmed by a DNA test, it makes sense to analyze other genes that have been associated with similar diseases. The possibilities are to test the whitish pupillary reflex and to do a fundus reflection.
The most common complication that can be expected with Norrie syndrome is the complete loss of sight. Many of those affected are already born blind, with other patients it is a progressive process, but mostly the eyesight is lost by the age of ten at the latest. To make matters worse, the disease is often not diagnosed until the retina has already completely detached.
If the detachment process is detected in time, vision can be preserved in some patients with the help of laser eye surgery. Some of those affected develop further complications over time. In particular, those affected develop signs of mental retardation. The cognitive abilities of affected children do not develop age-appropriately.
They show difficulties in learning and often also social behavior problems. In these cases, both drug treatment and psychotherapy are usually required. For the families of those affected, this is accompanied by a considerable additional care effort.
In the second half of life at the latest, the majority of patients show the onset of hearing loss, which can lead to complete hearing loss. However, this corresponds to the extreme extent of the disease, many patients can be helped permanently with a hearing aid.
When should you go to the doctor?
Das Norrie-Syndrom ist angeboren und wird meist unmittelbar nach der Geburt erkannt. Die Eltern des betroffenen Kindes müssen regelmäßig zum Arzt gehen, damit neue und ungewöhnliche Symptome abgeklärt und behandelt werden können. Sollte es infolge der bestehenden Symptome zu Unfällen oder Stürzen kommen, ist der Rettungsdienst zu alarmieren. Während der Therapie muss der Erkrankte weiterhin konstant ärztlich überwacht werden. Aufgrund des hohen Risikos für Frakturen und andere Komplikationen ist meist eine stationäre Behandlung in einer Fachklinik nötig.
In addition, the sick person must be supported by friends and acquaintances who can call the emergency doctor immediately in the event of a medical emergency. Depending on the type and severity of the symptoms, different specialists must be involved in the treatment. Opacity of the cornea as well as cataracts or eye tremors must be treated by an ophthalmologist. Hearing loss must be treated by an audiologist. If mental disabilities and/or behavioral problems occur, therapeutic measures are necessary. Parents also usually need the support of a psychologist.
Treatment & Therapy
So far, there are no adequate therapeutic options for causal healing. During treatment, only the various symptoms can be treated therapeutically, but not the causes. By the time the first diagnosis is made, the retina has usually already completely and irreversibly detached.
Surgery or laser treatment may be able to help those affected who have not completely lost their sight. Hearing aids and cochlear implants can also be used to treat progressive hearing loss.
In the case of conspicuous behavioral patterns or cognitive difficulties, there is the possibility of positively influencing this development through psychological counseling and special medication. Adequate care and attention from family, friends or caregivers is generally required. If this is the case, people who suffer from Norrie syndrome can still lead a fulfilling life.
Outlook & Forecast
The prognosis of Norrie syndrome is unfavorable. The affected person is usually male and is born with a genetic defect. The legal requirements of our country prohibit an intervention or a change in the human genetics. As a result, the causal disorder cannot be treated by doctors and medical professionals.
In addition, since the syndrome is associated with vision loss and cognitive impairment, there are difficulties in obtaining adequate treatment. The current medical possibilities do not allow the symptoms to be alleviated, so that vision can be restored to a normal level or intelligence develops according to average.
A further complication is that some complaints are not detected immediately after birth, but develop over the course of life. These lead to a deterioration in the general quality of life. In addition to behavioral problems, hearing loss is also possible.
Opportunities for early support are used, but are often not successful to a sufficient extent. With a quick diagnosis and the development of an individual treatment plan, the best results are achieved in the further course. Nevertheless, the disease represents a significant burden for those affected and their relatives. Coping with everyday life is not possible throughout life without help and support. Long-term therapies are necessary, which are changed and adjusted depending on the development of the symptoms.
Since the gene locus has been known, genetic examinations and counseling have played an important role. It is possible to identify the carriers and make use of prenatal diagnostics. Congenital blindness can occur more frequently within a family if the gene defect responsible for it does not occur as a mutation but is inherited from one generation to the next.
If a human geneticist is aware of the genetic defect, he can determine how high the risk is that his own child will be blind at birth. At best, however, he can also give the all-clear. In human genetic testing, the chromosomes are examined for changes. If there is a suspicion of a genetic defect, further complex tests can be carried out to check the gene constellations and to be able to assess the risk of possible inheritance.
Since the malformations caused by Norrie syndrome cannot be cured, there is no follow-up care in the strict sense. Regular check-ups by a specialist are indicated so that newly occurring symptoms can be classified. Treatment may relieve the symptoms or help to preserve vision for longer, for example. Depending on the severity of the visual and hearing impairments, those affected are dependent on help in everyday life.
If both defective vision and hearing loss occur, they can hardly find their way on their own and should always be accompanied. However, the home can be made accessible so that people with Norrie Syndrome can move freely in the home environment. If there is a reduction in intelligence or behavioral problems, these should be treated separately as far as possible.
In any case, it is advisable to visit a special school where the special needs of the children can be catered for. There they learn to develop their potential despite the limitations and achieve at least partial independence. By applying for a severely handicapped pass, the disadvantages caused by the visual and hearing impairments can be compensated for. If an accompanying person is required, they will receive free entry to many facilities. Tax breaks or a reduction in the broadcasting fee are also possible in the case of a proven severe sensory disorder.
You can do that yourself
For those affected, Norrie syndrome usually ends with the loss of hearing. If an early diagnosis is made, treatment measures can possibly save the hearing ability. The therapy can be supported by psychological counseling. Although this cannot alleviate the hearing loss itself, any behavioral problems or cognitive difficulties can be corrected with comprehensive care.
The hearing loss can be corrected with hearing aids and cochlear implants. Nevertheless, the parents are advised to support the child and to develop further measures to enable the child to lead a relatively problem-free life. For example, the parents can learn sign language or identify certain emergency signs with the child. In the long term, those affected by Norrie syndrome need comprehensive medical and therapeutic support, accompanied by the help of relatives and friends.
If the child continues to behave abnormally and thereby endangers itself or others, a specialist clinic must be consulted. It may also be necessary to change the medication or other measures can be taken to reduce the child’s suffering. Which measures are indicated in detail can be discussed in a comprehensive discussion with the responsible pediatrician.