###### Created: 2023-10-18 10:04 ###### Areas & Topics: #medicine #neurology ###### Note Type: #permanent ###### Connected to: [[Aspirin]] [[Nasal Polyps]] - Reye's Syndrome is an acute and life-threatening paediatric illness. - The syndrome is characterised by an acute non-inflammatory encephalopathy alongside fatty liver failure. - Australian Pathologist R.D.K Reye first described the syndrome in 1963, which then began a trend of national surveillance measures across the world to try and stop development of the condition. - In the UK, Reye's Syndrome is thankfully now very rare following national surveillance with only a handful of cases being reported each year. ### Aetiology - The exact aetiology of Reye's Syndrome is largely unknown, but it appears to be precipitated by a viral illness of some form. - The most common pathogens include influenza A, B and varicella. - It has also been shown that in children who developed Reye's Syndrome, around 80% had used some form of salicylate in the preceding 3 weeks. - This led to general advice being given that children under 16 should not be given aspirin or other salicylate-containing products, unless advised otherwise by a clinician. ### Pathophysiology - When a child experiences a viral illness, it is thought that this causes mitochondrial injury and/or dysfunction. - It is then thought that this mitochondrial injury occurring in the liver leads to an inability for the body to effectively metabolise fatty-acids and leads to a fatty liver developing. - High amounts of fat deposits in the liver reduce its ability to work effectively, which includes its ability to convert nitrogen waste into urea. - This nitrogen waste then builds up as ammonia, seeping into the blood and causing hyperammonaemia. - Once these high levels of ammonia reach the brain, for unknown reasons they lead to the development of encephalopathy in the patient. - it is also thought that this hyperammonaemia causes astrocyte oedema, leading to a diffuse cerebral oedema and thereby causing symptoms of raised intercranial pressure. - Alongside this, it is thought that the use of [[Aspirin]] or other salicylate based products may increase or prolong the damage to cellular mitochondria, further increasing the chance of the condition developing. ### Clinical Features - The symptoms of Reye syndrome highly tie into the underlying features of hepatic impairment, hyperammonaemia and raised ICP (resulting from cerebral oedema). - Patients will likely present with severe vomiting, confusion, lethargy and possibly tachycardia, hyperventilation, seizures or fits. - It is important to suspect Reye's Syndrome in the context of a patient who has recovered from a viral illness and/or used aspirin or salicylate containing products in the last 3 weeks. The CDC describes Reye's Syndrome as developing in 5 stages, which include: Stage 1 - Vomiting (usually lots) - Confusion - Sleepy/Lethargic Stage 2 - Stupor (meaning that only strong stimuli will stimulate the patient, and when not stimulated they are likely to be unresponsive) - UMN Signs - Hyperventilation and/or Tachycardia Stage 3 - Obtundation (a more severe form of lethargy where the patient is disinterested in the environment, slow to react to stimuli and drowsy/sleepy) - Decorticate Rigidity N.B. At this stage patients can be comatose Stage 4 - Comatose - Messed Up Pupillary Reflexes Stage 5 - Death ### Management - The management of Reye's syndrome is largely supportive, meaning treatment will largely be based on the patient's symptoms and condition at the time. ### Resources https://www.ncbi.nlm.nih.gov/books/NBK526101/ https://www.nhs.uk/conditions/reyes-syndrome/ https://bestpractice.bmj.com/topics/en-gb/1027 https://www.ncbi.nlm.nih.gov/books/NBK557504/ https://www.osmosis.org/notes/Encephalopathy#page-1 https://www.ncbi.nlm.nih.gov/books/NBK380/ https://reyessyndrome.rcpch.ac.uk/about-reyes-syndrome/management/