Neurology
It has been found that up to half of people with PTHS have epilepsy with different types of seizures that vary in severity. Someone with PTHS may have a first seizure as early as the first year of life or as late as early adulthood. Seizures can easily be misdiagnosed when there is apnoea (see glossary) as in both the lips and skin can go blue. Children with PTHS may show apnoea or hyperbreathing just before a seizure, but the abnormal breathing is not itself part of the seizure. Electroencephalographic (EEG) patterns in people with PTHS are typically abnormal, and the patterns will change over time. If the EEG is normal one should be careful not to miss that in fact, there is no seizure, but it is an apnoea. The EEG patterns usually are not specific to a certain type of seizure. As it is difficult to tell the difference between seizures and apnoea it is suggested that an EEG be carried out if in doubt and looked at with this in mind (R16). There is no need to make an EEG in everyone with PTHS. Valproic acid, levetiracetam, lamotrigine, and carbamazepine are the most commonly used seizure drugs but there are not enough data to say whether one drug is better than another (R17)
Other neurological (glossary) problems are not very common in people with PTHS. Seven of the 47 people with PTHS who attended the 2018 PTHS World Conference were shown to have a tremor (shake) that did not get worse over time. The common wide standing position and movement may be linked to problems with a person’s nervous system, but there has not been enough study on it. There is a noticeable difference in muscle tone in people with PTHS: three-quarter will have truncal (torso) hypotonia, and less than 10% has a high muscle tone (hypertonia). One-third has this high muscle tone in arms and legs. It has been suggested the difference in muscle tone is due to the autonomic nervous system being disrupted (see section 6).
Sleep problems are seen in a small number of those with PTHS with many parents saying that their child sleeps extremely well. Some parents mention that their child does not sleep through the night or have night terrors. Melatonin had been used by 10 of the 51 attendees of the World Conference in 2018: in two it had worked well, in six it had no effect and in the remaining two the result was uncertain. Sleep has not been looked at in full detail yet and further studies are needed.
Different brain scans (MRI) have been done and smaller changes in the formation of the brain have been seen in some but in most the scans just show normal results. Almost invariably the results are not important in how a child with PTHS should be looked after. So, it is suggested that an MRI is only needed when there are neurological signs and symptoms, such as repeated seizures but not in all children with PTHS. An MRI is also not needed just because a child has microcephaly (small head) (glossary) (R18)
Recommendations
R16 EEG studies should only be carried out when there are clear seizures or when one remains in doubt if someone with PTHS shows seizures or apnoea’s.
R17 Clinical seizures can be treated just the same as in the general population; there is no evidence that one specific drug works better than others.
R18 MRIs need only be carried out if there are neurological signs and symptoms that this would be useful. Microcephaly (small head) on its own does not mean a child should have an MRI.
