It might be helpful at this point to draw a distinction between the terms hereditaryA condition is hereditary if it results from the individual’s genetic make-up, being inherited from one or both parents. and congenitalAn abnormality, structural or otherwise, which is present at birth, although its presence may not become evident until later in life, if at all.. The word congenitalAn abnormality, structural or otherwise, which is present at birth, although its presence may not become evident until later in life, if at all. refers to how we are each made up as a result of our parentage, which is clearly similar in meaning to our heredity. When used to refer to medical conditions, however, the term is normally describing an abnormality that is present at birth. Such abnormalities are usually structural in nature, although they may not be externally apparent at the time. Importantly, they are not always genetic in origin but may have been caused by some environmental influence whilst in the womb. This is why a lot of attention is paid to possible harmful effects of any medicines or drugs taken during pregnancy. HereditaryA condition is hereditary if it results from the individual’s genetic make-up, being inherited from one or both parents. conditions, on the other hand, whilst being part of an individual’s make-up and therefore present at birth, may not be evident at the time, only coming to light later in life. In summary, not all congenitalAn abnormality, structural or otherwise, which is present at birth, although its presence may not become evident until later in life, if at all. abnormalities have a genetic origin and not all genetically based conditions are evident at birth.

As with congenitalAn abnormality, structural or otherwise, which is present at birth, although its presence may not become evident until later in life, if at all., the word hereditaryA condition is hereditary if it results from the individual’s genetic make-up, being inherited from one or both parents. can have different meanings according to the context in which it is used. An hereditaryA condition is hereditary if it results from the individual’s genetic make-up, being inherited from one or both parents. condition is generally seen as one in which there is an established genetic component. Geneticists can often provide estimates of the likelihood of such a condition being passed on to offspring. Many other conditions, however, which are not categorised as being hereditaryA condition is hereditary if it results from the individual’s genetic make-up, being inherited from one or both parents. disorders, are recognised as having hereditaryA condition is hereditary if it results from the individual’s genetic make-up, being inherited from one or both parents. components, or representing a familial trait. The risk of some cancers, for example, may be higher for an individual who has a history of the condition in the family. Even appendicitis has a tendency to run in families but would not normally be classified as an hereditaryA condition is hereditary if it results from the individual’s genetic make-up, being inherited from one or both parents. disorder.

So where do Chiari malformations fit in? Type 2 malformations form part of the spectrum of spina bifidaDuring development, at each level of the spine two plates of bone migrate towards one another and fuse, in the midline, forming what are referred to as spinous processes. It is the tips of these spinous processes that we feel when running a finger down our spines. Sometimes one or more of the pairs of plates fail to fuse adequately, such that two, shorter spinous processes form on each side of the midline. This is what is referred to as spina bifida. It affects most commonly the lower part of the spine, in the lumbar region. Many people may quite unaware that they have such split (or, more specifically, never joined), spinous processes. Plain radiographs, or magnetic resonance imaging, may… malformations and both spina bifidaDuring development, at each level of the spine two plates of bone migrate towards one another and fuse, in the midline, forming what are referred to as spinous processes. It is the tips of these spinous processes that we feel when running a finger down our spines. Sometimes one or more of the pairs of plates fail to fuse adequately, such that two, shorter spinous processes form on each side of the midline. This is what is referred to as spina bifida. It affects most commonly the lower part of the spine, in the lumbar region. Many people may quite unaware that they have such split (or, more specifically, never joined), spinous processes. Plain radiographs, or magnetic resonance imaging, may… and Chiari type 2 malformations are commonly accompanied by the condition known as hydrocephalusMeaning “water on (or in) the brain”, this word refers to an anatomical state in which there is an abnormally large volume of cerebrospinal fluid within the head. Most often this excess fluid accumulates within the ventricles of the brain and the word ventriculomegaly may be used synonymously. Some authorities teach that the word ventriculomegaly simply describes large ventricles and that the word hydrocephalus should be reserved to indicate that the enlarged ventricles are generating symptoms. Cerebrospinal fluid may also accumulate over the surface of the brain but inside the dura, in which case the term “external hydrocephalus” is sometimes used. Read more. Most cases will be evident at or shortly after birth and are therefore normally categorised as congenitalAn abnormality, structural or otherwise, which is present at birth, although its presence may not become evident until later in life, if at all. malformations. Spina bifidaDuring development, at each level of the spine two plates of bone migrate towards one another and fuse, in the midline, forming what are referred to as spinous processes. It is the tips of these spinous processes that we feel when running a finger down our spines. Sometimes one or more of the pairs of plates fail to fuse adequately, such that two, shorter spinous processes form on each side of the midline. This is what is referred to as spina bifida. It affects most commonly the lower part of the spine, in the lumbar region. Many people may quite unaware that they have such split (or, more specifically, never joined), spinous processes. Plain radiographs, or magnetic resonance imaging, may… itself is something that can have a familial component, and therefore so can type 2 malformations.

Chiari type 1 hindbrain hernias, on the other hand, most often come to light in adolescence or in early to mid-adult life. Chiari type 1 is not, therefore, usually categorised as being congenitalAn abnormality, structural or otherwise, which is present at birth, although its presence may not become evident until later in life, if at all.. The issue is further complicated by our increasing appreciation that Chiari type 1 is not a single condition but, rather, an internal anatomical feature (often an incidental radiological finding) that can result from a number of different underlying causes. The commonest cause is a mismatch between the size of that part of the brain referred to as the cerebellumThis word means the “little brain” and refers to a large part of the brain that sits in lowermost part of the skull, at the back of the head, immediately above the top of the spine. This part of the skull is known as the posterior fossa. and the part of the skull in which it is contained, the so-called posterior fossaThat part of the cranial cavity that lies below the tentorium and which contains the brain stem and the cerebellum.. In other words it is a consequence of the size and shape of a particular body structure, albeit an internal one.

The question, then, is how likely it is that parents with Chiari might pass on this anatomical feature to their offspring. We cannot answer this with any confidence and certainly cannot give a percentage likelihood of it happening. It is a bit like asking how likely it is that a child will develop the same shape of nose as one or other parent. Furthermore, whereas we can, sometimes, pick out a specific facial characteristic of a parent, in a child, more often than not such a resemblance is partial only. Whilst it may be reasonable to suggest that some cases of Chiari type 1 malformation could, in part, have a genetic basis, being the result of DNA programming, we do not regard Chiari malformationAn anatomical abnormality affecting the lowermost part of brain, where it joins the spinal cord, at the top of the neck. Various sub-types are described – see under their individual names. The term hindbrain hernia is sometimes used to incorporate all forms. as an hereditaryA condition is hereditary if it results from the individual’s genetic make-up, being inherited from one or both parents. disorder. Genetic counselling is certainly not currently advocated by specialists dealing with Chiari malformations, although genetic studies are sometimes undertaken in a research setting.

We can’t rule out the influence of environmental factors, affecting development inside the womb, as a cause of Chiari type 1 malformations, but there is no strong evidence to indicate that this is the case. Furthermore, given the high prevalence of low cerebellar tonsilsThe lower-most part of the cerebellum is made up of a pair of structures, one on each side of the midline, known as the tonsils. These structures have no relationship with the tissue at the back of the throat, which becomes inflamed and sore with a viral infection. It is simply the case that the same Latin term was applied by (presumably) different anatomists, at different times and working in different places, to name these very different body parts. The word tonsilla literally means a stump; Roman ships were moored to “tonsilla” when in port. in the population as a whole, as revealed by MR imaging (about 1% overall), it is possible that some “clustering” could occur in a family simply by chance, without any genetic influence.

The answer to the original question, therefore, is “possibly, in some cases”. A parent with Chiari type 1 malformation may pass the same genetic trait to a child but the likelihood of this happening is not high and the consequences, should it happen, will not necessarily be troublesome. Should a child of a Chiari parent develop symptoms, which can be similar to or different from those experienced by the parent, then the child can always be referred for assessment and counselling by a suitably experienced specialist. A need for any subsequent intervention is far from inevitable. People with Chiari type 1 malformations need not avoid starting a family, just on the basis of their condition. There may be obstetric considerations around the time of delivery but these are separate issues to be discussed at the time, between the individual, her obstetrician and her neurosurgeon. With Chiari type 2, and its associated hydrocephalusMeaning “water on (or in) the brain”, this word refers to an anatomical state in which there is an abnormally large volume of cerebrospinal fluid within the head. Most often this excess fluid accumulates within the ventricles of the brain and the word ventriculomegaly may be used synonymously. Some authorities teach that the word ventriculomegaly simply describes large ventricles and that the word hydrocephalus should be reserved to indicate that the enlarged ventricles are generating symptoms. Cerebrospinal fluid may also accumulate over the surface of the brain but inside the dura, in which case the term “external hydrocephalus” is sometimes used. Read more and spina bifidaDuring development, at each level of the spine two plates of bone migrate towards one another and fuse, in the midline, forming what are referred to as spinous processes. It is the tips of these spinous processes that we feel when running a finger down our spines. Sometimes one or more of the pairs of plates fail to fuse adequately, such that two, shorter spinous processes form on each side of the midline. This is what is referred to as spina bifida. It affects most commonly the lower part of the spine, in the lumbar region. Many people may quite unaware that they have such split (or, more specifically, never joined), spinous processes. Plain radiographs, or magnetic resonance imaging, may…, it is likely that such discussions will take place anyway.