Streff syndrome is a vision condition primarily exhibited by children under periods of visual or emotional stress.

Frequently patients will have reduced stereopsis, large accommodative lag on dynamic retinoscopy, and a reduced visual field (tubular or spiral field). Streff Syndrome was first described in 1962 by an optometrist, Dr. John Streff as Non-malingering syndrome. In 1962, Dr. Streff and Dr. Richard Apell expanded the concept to add early adaptive syndrome as a precursor to Streff syndrome. Dr. Streff believed the visual changes were induced by stress from reading. There is dispute on the taxonomy of functional vision defects. Some research indicates that Streff syndrome may be caused by a dysfunction in the magnocellular pathway of the retinal ganglion cells. These cells are only 10% of the retinal nerve cells and register motion detection.

Early Adaptive Syndrome

Most optometrists agree that Streff syndrome is a generalized reduction in visual performance that is not caused by structural damage. It is a disease involving vision distress primarily of the accommodation system. Hans Selye described stress, distress and eustress. It is most common in girls ages 8 to 14. Hand held reading material is often positioned excessively close. Reading aloud shows signs of elevated pitch and stumbling over common words. History of homework avoidance and falling class performance are often present. If the patient is directed to read aloud and +.50 lenses are then used, there is usually a dramatic improvement as observed by patient and parent. Abnormal results on color vision or visual field testing is not uncommon. Visual field often presents as constricted 'tubular' at multiple test distances. The poor visual performance is understood as distress, and treatments are usually to provide the patient with low powered reading glasses. The "relaxing" nature of reading glasses is believed to reduce the near vision stress and allow normal function. The emotional effects of chronic near vision stress are also reduced.

The "non-Malingering" name is a refutation that the patient is malingering.

As of 2014, no clinical trials had been conducted to determine what treatments are safe and effective; a few case reports had been published describing treatment of small numbers of people (two to twelve per report) with clomipramine, flunarizine, nifedipine, topiramate, carbamazepine, methylphenidate. Studies suggest that education and reassurance can reduce the frequency of EHS episodes. There is some evidence that individuals with EHS rarely report episodes to medical professionals.

There have not been sufficient studies conducted to make conclusive statements about prevalence nor who tends to suffer EHS. One study found that 13.5% of a sample of undergrads reported at least one episode over the course of their lives, with higher rates in those also suffering from sleep paralysis.

The optokinetic response is a combination of a slow-phase and fast-phase eye movements. It is seen when an individual follows a moving object with their eyes, which then moves out of the field of vision at which point their eye moves back to the position it was in when it first saw the object. The reflex develops at about 6 months of age.

Optokinetic nystagmus (OKN) is nystagmus that occurs in response to a rotation movement. It is present normally. The optokinetic response allows the eye to follow objects in motion when the head remains stationary (e.g., observing individual telephone poles on the side of the road as one travels by them in a car, or observing stationary objects while walking past them).

If an optokinetic drum is available, rotate the drum in front of the patient. Ask the patient to look at the drum as you rotate it slowly. If an optokinetic drum is not available, move a strip of paper with alternating 2-inch black and white strips across the patient's visual field. Pass it in front of the patient's eye at reading distance while instructing the patient to look at it as it rapidly moves by. With normal vision, a nystagmus develops in both adults and infants. The nystagmus consists of initial slow phases in the direction of the stimulus (smooth pursuits), followed by fast, corrective phases (saccade). Presence of nystagmus indicates an intact visual pathway.

Another effective method is to hold a mirror in front of the patient and slowly rotate the mirror to either side of the patient. The patient with an intact visual pathway will maintain eye contact with herself or himself. This compelling optokinetic stimulus forces reflex slow eye movements.

OKN can be used as a crude assessment of the visual system, particularly in infants. When factitious blindness or malingering is suspected, check for optokinetic nystagmus to determine whether there is an intact visual pathway.

Currently, purine replacement via S-adenosylmethionine (SAM) supplementation in people with Arts syndrome appears to improve their condition. This suggests that SAM supplementation can alleviate symptoms of PRPS1 deficient patients by replacing purine nucleotides and open new avenues of therapeutic intervention. Other non-clinical treatment options include educational programs tailored to their individual needs. Sensorineural hearing loss has been treated with cochlear implantation with good results. Ataxia and visual impairment from optic atrophy are treated in a routine manner. Routine immunizations against common childhood infections and annual influenza immunization can also help prevent any secondary infections from occurring.

Regular neuropsychological, audiologic, and ophthalmologic examinations are also recommended.

Carrier testing for at-risk relatives and prenatal testing for pregnancies at increased risk are possible if the disease-causing mutation in the family is known.

Hospitalization may be necessary during the acute phase of symptoms, and psychiatric care if the patient is a danger to self or others. A neurological consult is advised to rule out any organic cause.

In the 1980s and 1990s, several trials of melatonin administration to totally blind individuals without light perception produced improvement in sleep patterns, but it was unclear at that time if the benefits were due to entrainment from light cues. Then, using endogenous melatonin as a marker for circadian rhythms, several research groups showed that appropriately timed melatonin administration could entrain free-running rhythms in the totally blind. For example, Sack et al. found that 6 out of 7 patients treated with 10 mg melatonin at bedtime were normally entrained. When the dose was gradually reduced to 0.5 mg in three of the subjects, entrainment persisted. Subsequently, it was shown that treatment initiated with the 0.5 mg dose produced entrainment. One subject who failed to entrain at a higher dose was successfully entrained at a lower dose. A low dose produces melatonin blood levels that are similar to the concentrations naturally produced by nightly pineal secretion.

Products containing melatonin are available as dietary supplements in the United States and Canada, available over the counter. These "supplements" do not require FDA approval. As prescription drugs may be prescribed off-label, treatment recommendations for non-24 in the blind may vary.

There has been a constant growth in the field of melatonin and melatonin receptor agonists since the 1980s. In 2005 Ramelteon (Rozerem) was the first melatonin agonist to be approved in the United States (US), indicated for insomnia treatment in adults. Melatonin in the form of prolonged release (trade name Circadin) was approved in 2007 in Europe (EU) for use as a short-term treatment, in patients 55 years and older, for primary insomnia. Tasimelteon (trade name Hetlioz) received FDA-approval in January 2014 for persons diagnosed with non-24. TIK-301 (Tikvah Therapeutics, Atlanta, USA) has been in phase II clinical trial in the United States since 2002 and the FDA granted it orphan drug designation in May 2004, for use as a treatment for circadian rhythm sleep disorder in blind individuals without light perception as well as individuals with tardive dyskinesia.

The disorder is extraordinarily rare. While individuals of all backgrounds have been reported with the disorder, there is a higher inclination towards males (75% or more). The average age of those with Ganser syndrome is 32 and it stretches from ages 15 to 62 years old. It has been reported in children.

The disorder is apparently most common in men and prisoners, although prevalence data and familial patterns are not established.

There are an estimated 140,000 people with N24 – both sighted and blind – in the European Union, a total prevalence of approximately 3 per 10,000, or 0.03%. It is unknown how many individuals with this disorder do not seek medical attention, so incidence may be higher. The European portal for rare diseases, Orphanet, lists Non-24 as a rare disease by their definition: fewer than 1 affected person for every 2000 population. The US National Organization for Rare Disorders (NORD) lists Non-24 as a rare disease by its definition.

Treatments exist for the various symptoms associated with XXXY syndrome. Testosterone therapy, which is giving affected individuals doses of testosterone on a regular basis, has been shown to reduce aggressive behavior in these patients. But, this therapy has also been associated with negative side effects: worsening of behavior, and osteoporosis. Not all individuals are applicable for testosterone therapy, as the best results are often achieved when dosage begins at the initiation of puberty, and these individuals are often diagnosed at a later age, or not at all. Testosterone therapy has been shown to have no positive effect on fertility.

Consideration of the psychological phenotype of individuals with XXXY should be taken into account when treating these patients, because these traits affect compliance with treatments. When caught early, Taurodontism can be treated with a root canal and is often successful. Appropriate planning to avoid Taurodontism is possible, but this syndrome must be diagnosed early, which is not common. Taurodontism can often be detected as a symptom of XXXY syndrome before other characteristics develop, and can be an early indicator for it. Surgical treatments to correct joint problems, such as hip dysplasia are common, and are often successful alongside physiotherapy.

Those with XXXY syndrome can also attend speech therapy. This form of therapy helps patients to understand and produce more complex language. Those with XXXY syndrome tend to experience more severe speech delays, so this form of treatment can be very beneficial to them, and can help them to communicate better with other people.

Since hypotonia is common in those with this syndrome, physical therapy can also be helpful. This form of therapy may help these individuals develop muscle tone, and increase balance and coordination.

PEHO syndrome is a progressive encephalopathy with edema, hypsarrhythmia and optic atrophy. It is a very rare disease, one of the Finnish heritage diseases, although approximately half of the cases reported so far are not-Finnish and have been described worldwide .

It has been suggested that it may also be present in Australian and American populations.

Treatment requires a firm and transparent diagnosis based on positive features which both health professionals and patients can feel confident about. It is essential that the health professional confirms that this is a common problem which is genuine, not imagined and not a diagnosis of exclusion.

Confidence in the diagnosis does not improve symptoms, but appears to improve the efficacy of treatments such as physiotherapy which require altering established abnormal patterns of movement.

A multi-disciplinary approach to treating functional neurological disorder is recommended.

Treatment options can include:

- Physiotherapy and occupational therapy

- Medication such as sleeping tablets, painkillers, anti-epileptic medications and anti-depressants (for patients suffering with depresssion co-morbid or for pain relief)

Physiotherapy with someone who understands functional disorders may be the initial treatment of choice for patients with motor symptoms such as weakness, gait (walking) disorder and movement disorders. Nielsen et al. have reviewed the medical literature on physiotherapy for functional motor disorders up to 2012 and concluded that the available studies, although limited, mainly report positive results. Since then several studies have shown positive outcomes. In one study, up to 65% of patients were very much or much improved after five days of intensive physiotherapy even though 55% of patients were thought to have poor prognosis. In a randomised controlled trial of physiotherapy there was significant improvement in mobility which was sustained on one year follow up. In multidisciplinary settings 69% of patients markedly improved even with short rehabilitation programmes. Benefit from treatment continued even when patients were contacted up 25months after treatment.

For patients with severe and chronic FND a combination of physiotherapy, occupational therapy and cognitive behavioural therapy may be the best combination with positive studies being published in patients who have had symptoms for up to three years before treatment.

Cognitive behavioural therapy (CBT) alone may be beneficial in treating patients with dissociative (non-epileptic) seizures. A randomised controlled trial of patients who undertook 12 sessions of CBT which taught patients how to interrupt warning signs before seizure onset, challenged unhelpful thoughts and helped patients start activities they had been avoiding found a reduction in the seizure frequency with positive outcomes sustained at six month follow up. A large multicentre trial of CBT for dissociative (non-epileptic) seizures started in 2015 in the UK.

For many patients with FND, accessing treatment can be difficult. Availability of expertise is limited and they may feel that they are being dismissed or told 'it's all in your head' especially if psychological input is part of the treatment plan. Some medical professionals are uncomfortable explaining and treating patients with functional symptoms. Changes in the diagnostic criteria, increasing evidence, literature about how to make the diagnosis and how to explain it and changes in medical training is slowly changing this

After a diagnosis of functional neurological disorder has been made, it is important that the neurologist explains the illness fully to the patient to ensure the patient understands the diagnosis.

Some, but not all patients with FND may experience low moods or anxiety due to their condition. However, they will often not seek treatment due being worried that a doctor will blame their symptoms on their anxiety or depression.

It is recommended that the treatment of functional neurological disorder should be balanced and involve a whole-person approach. This means that it should include professionals from multiple departments, including neurologists, general practitioners (or primary health care providers), physiotherapists, occupational therapists. At the same time, ruling out secondary gain, malingering, conversion disorder and other factors, including the time and financial resources involved in assessing and treating patients who demand hospital resources but would be better served in psychological settings, must all be balanced.

Treatment consists of several such anesthetic injections, sometimes combined with corticosteroids. Such an approach yields persistent pain relief in two-thirds of patients. This beneficial effect on pain has been demonstrated in a prospective double blind trial. The physical volume of the injection may also break apart the adhesions or fibrosis responsible for the entrapment symptoms.

Patients who do not respond to a stratagem of repetitive local trigger point injections can be offered a surgical approach. Terminal branches of an intercostal nerve are removed at the level of the anterior sheath of the rectus abdominal muscle ('anterior neurectomy'). Several larger series demonstrated a successful response in approximately two out of three patients, which was confirmed in another prospective double blind surgical trial: 73% of the patients who underwent a neurectomy were pain free, compared to 18% in the non-nerve resected group. Patients not responding to an anterior neurectomy, or those in whom the pain syndrome recurs after an initial pain free period (10%) may choose to undergo secondary surgery. This involves a repeated exploration combined with a posterior neurectomy. This procedure has been shown to be beneficial in 50% of cases.

Research is ongoing in many aspects of functional neurological disorders but large studies are needed to definitely answer key questions including:

What is the best treatment for patients with FND? Even disorders like multiple sclerosis and Parkinson's disease have no definite known cause. The importance of increased awareness in the medical world of what constitutes a positive diagnosis of FND and what the best treatments are may, in the short term, be where research is focused.

Rapid blood transfusions, to correct anemia and raise blood pressure, may improve PION outcomes. In one report of a related disease, hypotension-induced AION, 3 out of 3 patients who received rapid transfusions reported partial recovery of vision. While rapid transfusions offer some hope, the prognosis for perioperative PION remains poor. Prevention remains the best way to reduce PION.

One retrospective report proposes that incidence of PION could be reduced in high-risk cases by altering surgical management. For example, for patients undergoing spine surgery, measures could be taken to minimize intraoperative hypotension, to accelerate the process of blood replacement, and to aggressively treat facial swelling.

If a diagnosis of GCA is suspected, treatment with steroids should begin immediately. A sample (biopsy) of the temporal artery should be obtained to confirm the diagnosis and guide future management, but should not delay initiation of treatment. Treatment does not recover lost vision, but prevents further progression and second eye involvement. High dose corticosteroids may be tapered down to low doses over approximately one year.

Though there is limited evidence, outcomes appear to be relatively poor with a review of outcome studies finding that two thirds of PNES patients continue to experience episodes and more than half are dependent on social security at three-year followup. This outcome data was obtained in a referral-based academic epilepsy center and loss to follow-up was considerable; the authors point out ways in which this may have biased their outcome data. Outcome was shown to be better in patients with higher IQ, social status, greater educational attainments, younger age of onset and diagnosis, attacks with less dramatic features, and fewer additional somatoform complaints.

This syndrome is predominantly found in young women, but also occurs in children, teenagers and octogenarians.

Treatment may involve investigation, reassurance and explanation, and possibly specialist treatment such as antidepressants or cognitive behavioral therapy.

In mild cases, individuals with XXXY syndrome may lead a relatively good life. These individuals may face difficulties in communicating with others due to their language-based deficits. These deficits may make forming bonds with others difficult, but fulfilling relationships with others are still achievable. Those with higher scores in adaptive functioning are likely to have higher quality of life because they can be independent.

A mutation in the ZNHIT3 gene - a nuclear zinc finger protein involved in transcriptional regulation and in small nucleolar ribonucleoprotein particle assembly has been shown to be the cause of the Finnish-type of PEHO syndrome. However, the syndrome appear to be genetically heterogeneous and it might reflect an underlying genetic tubulinopathy, with biallelic mutations in the gene PRUNE1 also identified in non-Finnish patients with PEHO syndrome.

There is no evidence-based criteria for treating SPS, and there have been no large controlled trials of treatments for the condition. The rarity of the disease complicates efforts to establish guidelines.

GABA agonists, usually diazepam but sometimes other benzodiazepines, are the primary treatment for SPS. Drugs that increase GABA activity alleviate muscle stiffness caused by a lack of GABAergic tone. They increase pathways that are dependent upon GABA and have muscle relaxant and anticonvulsant effects, often providing symptom relief. Because the condition worsens over time, patients generally require increased dosages, leading to more side effects. For this reason, gradual increase in dosage of benzodiazepines is indicated. Baclofen, a GABA agonist, is generally used when individuals taking high doses of benzodiazepines have high side effects. In some cases it has shown improvements in electrophysiological and muscle stiffness when administered intravenously. Intrathecal baclofen administration may not have long-term benefits though, and there are potential serious side effects.

Treatments that target the autoimmune response are also used. Intravenous immunoglobin is the best second-line treatment for SPS. It often decreases stiffness and improves quality of life and startle reflex. It is generally safe, but there are possible serious side effects and it is expensive. The European Federation of Neurological Societies suggests it be used when disabled patients do not respond well to diazepam and baclofen. Steroids, rituximab, and plasma exchange have been used to suppress the immune system in SPS patients, but the efficacy of these treatments is unclear. Botulinum toxin has been used to treat SPS, but it does not appear to have long-term benefits and has potential serious side effects. In paraneoplastic cases, tumors must be managed for the condition to be contained. Opiates are sometimes used to treat severe pain, but in some cases they exacerbate symptoms.

Jeavons syndrome is a lifelong disorder, even if seizures are well controlled with antiepileptic drugs. Men have a better prognosis than women. There is a tendency for photosensitivity to disappear in middle age, but eyelid myoclonia persists. It is highly resistant to treatment and occurs many times a day, often without apparent absences and even without demonstrable photosensitivity.