What is ROHHAD?
The name is an abbreviation of: Rapid-onset Obesity, Hypoventilation, Hypothalamic and Autonomic Dysfunction
It is a very rare disease with several associated problems: obesity, hypoventilation, hormonal problems, problems regarding the automatic control of body temperature, sweating, and heart rate and blood pressure changes, . Patients may also have changes in behaviour, such as aggression or showing excessive hunger and thirst. Respiratory symptoms can be severe, even to the point of havingrespiratory arrest needing resuscitation. Patients may also have eye disorders like strabismus (squint)
or differences in pupil sizes. Obesity is a problem of major concern, even being confused as the cause of hypoventilation and missing the diagnosis of ROHHAD
What causes ROHHAD?
The cause of ROHHAD is unknown; since the disease has been reported in two members of the same family, it is thought to have a genetic origin. The disease involves a disorder of the hypothalamus, a part of the brain which controls some important basic functions, such as: hunger, thirst, growth, sexual development, thyroid function, breathing and behaviour.
How is hypoventilation diagnosed?
Hypoventilation is more common during sleep and can be diagnosed with different techniques:
Sleep oximetry recording. This will detect falls in levels of oxygen in the blood, but fails to detect less severe problems like breathing pauses (apnoea) without drops in oxygen. As apnoeic pauses can be normal, other types of recording will usually be needed.
What’s wrong with the hormones?
|Sleep cardiorespiratory recording.
This study will detect apnoeic pauses,s but lacks information about the quality of sleep. It may happen that a patient has no apnoeas because they have not slept deeply enough to show the disorder.
This is the best exam that can be performed since gives all the needed information to evaluate breathing during sleep.
Diurnal (daytime) hypoventilation can be diagnosed by monitoring SpO2 and CO2 levels during the day. Detection of SpO2 < 95% and CO2 > 50 mmHg (6.7 kPa) allows the diagnosis of vigil hypoventilation.
Several hormone disorders occur together in ROHHAD. There may be inadequate production of hormones so that supplements are needed, including from: 1)the thyroid gland in the neck, needing thyroxine, 2) adrenal glands above the kidneys, so that cortisol is needed; and 3) the ovaries or testes, so that sex hormones including oestrogens or testosterones are neede. The regulation of thirst and hunger also depend on some hormonal control and can be faulty in ROHHAD.What happens in puberty?
Because of the lack of some hormones that are needed during puberty to promote growth and sexual development, puberty may be delayed and extra hormonal therapy should be considered. What’s wrong with the nervous system?
People with ROHHAD have a normal body movements and thinking, and achieve normal intellectual functions like other people. They can have disorders of the autonomic (automatic) nervous system, however, which controls the heart rate, blood pressure, breathing, sweating, body temperature, bowel movements, etc. Affected boys and girls may show changes in the normal workings of these body functions.Does the condition change over time?
As so few patients have been described up till now, relatively litteis known about the disease. One paper about ROHHAD reports that patients commonly show the disease in the first few years of life, the first sign often being obesity. Obesity may be associated with the development of hormonal disorders, like an increase in the prolactin levels (from the pituitary gland in the brain), adrenal and thyroid insufficiency. Hypoventilation may follow after years. The disease does not improve with time. How does hypoventilation show?
Hypoventilation can happen suddenly, sometimes after anaesthesia, for example, for adeno-tonsillectomy. Hypoventilation may also result in sudden respiratory arrest. Thismight be prevented by performing a sleep study in children who suddenly become obese, as this sign often occurs before hypoventilation. Is the hypoventilation managed differently to CCHS?
Hypoventilation may have a range of severity. Some patients may have only nocturnal hypoventilation, others 24 hours a day hypoventilation. Those patients who need mechanical ventilation just during sleep are frequently managed with mask ventilation, while those needing 24 hours a day ventilation have been treated with ventilation through a tracheostomy.How is the obesity managed?
Obesity can be managed with both hormonal and dietary control. It may aggravate any breathing problems during sleep and needs to be managed so that body weight is reduced.Are there risks of tumours?
Tumours have been described in ROHHAD patients. They are mainly tumours of the abdomen, deriving from nerve cells. These tumours should be screened for in ROHHAD patients so that there is early diagnosis and removal, if needed.What more is going to be learnt about ROHHAD disease?
The genetic origin of the disease will soon be defined and allow genetic counselling for parents and relatives.
A European registry of CHS patients, including those with ROHHAD, will help to better define this very rare disease. More data from patients will help our understanding of both the diagnosis and treatment of the condition.