Gender, head size and disease: a hypothesis related to posterior fossa growth
1hfw@dircon.co.uk
Insights
Gender-based differences in fetal head size influence disease risk. Smaller head size is linked to spina bifida, while larger head size is associated with autism in males.
Area of Science:
- Neuroscience
- Developmental Biology
- Pediatrics
Background:
- Head size differences between genders are hypothesized to influence disease incidence.
- Smaller head size is associated with spina bifida, and larger head size with autism.
Purpose of the Study:
- To investigate the hypothesis that gender-specific head size variations impact disease predisposition.
- To explore the role of the posterior fossa in regulating intracranial cerebrospinal fluid (CSF) pressure and its relation to head size and disease.
Main Methods:
- The study proposes a hypothesis based on existing literature and physiological principles of cerebrospinal fluid (CSF) pressure transmission.
- Analysis of fetal development, posterior fossa anatomy, and their influence on intracranial pressure dynamics.
Main Results:
- Larger posterior fossa spaces in male fetuses allow higher intracranial CSF pressure peaks, leading to larger head size.
- Restricted posterior fossa growth disproportionately affects females, correlating with higher spina bifida incidence and smaller fetal head size.
- Fetal surgery for spina bifida can expand posterior fossa CSF spaces, increasing head circumference post-surgery.
- Males' susceptibility to autism is linked to accelerated head growth in early childhood, potentially related to their larger average head size.
Conclusions:
- The size of the posterior fossa and its influence on CSF pressure transmission are critical factors in determining fetal head size.
- Gender-specific differences in posterior fossa development contribute to the differential incidence of spina bifida and autism.
Abstract:
This hypothesis proposes that the difference in head size between the genders has a bearing on disease incidence. Smaller head size predisposes to spina bifida and larger head size predisposes to autism. In the fetus, the posterior fossa has a regulatory influence on maximum intracerebral cerebrospinal fluid (CSF) pressure. CSF pressure pulsations are generated by movements in the chest and abdomen and transmitted to the intracranial CSF spaces via the posterior fossa. The efficiency of transmission of pressure to the head is influenced by the size of posterior fossa CSF spaces. The larger posterior fossa in the male fetus allows higher peaks of pressure in the lateral ventricles than the female, resulting in larger head size. Restriction of posterior fossa growth has a greater influence on females than males. This leads to a greater incidence of spina bifida in females, where reduced head size is characteristic in the fetal stages. Fetal surgery for spina bifida expands posterior fossa CSF spaces and improves transmission of pressure waves generated in the fetal abdomen and thorax into the head. This results in an increase in head circumference following surgery. Males are susceptible to autism where head growth is accelerated in early childhood. This is because they have a larger average head size.
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