obsolete macrocephaly

Macrocephaly: An Overview

Macrocephaly refers to an absolute term where the head size exceeds a certain centile, typically above the 97th centile [5]. This condition can be due to various factors such as hydrocephalus (increased cerebrospinal fluid), megalencephaly (increased brain volume), or thickening of the skull [6].

Causes and Associations

Macrocephaly has been associated with several conditions, including:

• Hydrocephalus: A condition where there is an accumulation of cerebrospal fluid in the brain, leading to increased head size [4].
• Megalencephaly: A condition where the brain volume is increased, leading to macrocephaly [6].
• Thickening of the skull: This can also contribute to macrocephaly [6].

Prevalence and Clinical Significance

Macrocephaly has been observed in a significant proportion of children, with one study finding that 16.7% of a sample had macrocephaly, which is a higher proportion than expected [8]. Macrocephaly has also been associated with learning disabilities, with some studies suggesting that up to 16% of children with learning disabilities may have macrocephaly [14].

Differential Diagnosis

Macrocephaly can be due to various causes, and a comprehensive evaluation is necessary to determine the underlying cause. This includes imaging modalities such as ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) [15]. The differential diagnosis for macrocephaly is extensive and requires a systematic approach.

References

[4] Pirozzi, F. (2018). Environmental factors associated with macrocephaly. Cited by 92. [5] Macrocephaly can be due to hydrocephalus or ventriculomegaly, not true megalencephaly [4]. [6] Macrocephaly is an absolute term where the head size exceeds a certain centile, typically above the 97th centile [5]. This condition can be due to various factors such as hydrocephalus (increased cerebrospinal fluid), megalencephaly (increased brain volume), or thickening of the skull [6]. [8] Fombonne, E. (1999). Prevalence and clinical significance of macrocephaly in a sample of children. Cited by 467. [14] Gupta, A. (2019). Macrocephaly and learning disabilities: A systematic review. Cited by 6. [15] Macrocephaly is a relatively common presenting symptom in the pediatric population at routine well-child examinations and a common indication for neuroimaging [15].

Obsolete Macrocephaly (Greig Cephalopolysyndactyly Syndrome)

Macrocephaly, also known as Greig cephalopolysyndactyly syndrome (GCPS), is a rare genetic disorder characterized by physical abnormalities affecting the fingers and toes (digits). The signs and symptoms of this condition are:

• Physical Abnormalities: Affected individuals may have extra fingers or toes, webbing between fingers or toes, and other skeletal abnormalities.
• Macrocephaly: A larger than normal head circumference is a hallmark of GCPS. This can be present at birth and may be accompanied by other physical abnormalities.

Other Possible Signs and Symptoms

In some cases, individuals with macrocephaly (GCPS) may experience:

• Delayed Developmental Milestones: Affected children may experience delays in reaching developmental milestones such as sitting, standing, or walking.
• Prominent Veins on the Scalp: Visible veins on the scalp can be a sign of increased pressure within the skull.
• Fullness of the Anterior Fontanelle: The soft spot on the baby's head (fontanelle) may appear full or bulging.

Important Note

Macrocephaly, in itself, is not a condition but rather a symptom that may indicate an underlying issue. A healthcare professional will assess the individual's overall health and medical history to determine the cause of macrocephaly.

References:

• [10] Macrocephaly is often present at birth.
• [12] Other possible signs and symptoms may include delayed developmental milestones, prominent veins on the scalp, fullness of the anterior fontanelle (soft spot on your baby’s head), or ...
• [13] Macrocephaly refers to an overly large head in infants. It is not a condition in itself, but it may be a symptom of other conditions or complications in the brain.
• [14] Signs and symptoms of the infantile form typically include macrocephaly, severe DD and regression, seizures, spasticity, and ataxia.

Based on the provided context, it appears that there are several diagnostic tests that were once used to diagnose macrocephaly, but are now considered obsolete.

• In vivo loading tests using lysine or prolonged fasting tests are potentially harmful and obsolete [8].
• Use of in vitro loading tests is also considered obsolete for diagnosing macrocephaly [8].

It's worth noting that these tests were likely used in the past to diagnose macrocephaly, but have since been replaced by more modern and effective diagnostic methods.

In contrast, other diagnostic tests such as:

• Head CT scan
• MRI of the head
• Cranial ultrasound
• Urine organic acid analysis
• Plasma amino acid analysis
• 2-MBAD gene sequencing

are still considered relevant for diagnosing macrocephaly [2, 7].

It's also worth noting that an accurate diagnosis of patients with macrocephaly requires a multidisciplinary team approach and assessments are crucial to promptly recognize a specific macrocephaly class and in turn pursue targeted diagnostic testing [10].

Treatment Options for Obsolete Macrocephaly

Macrocephaly, or large head size, can be a sign of an underlying medical condition that requires treatment. In some cases, drug treatment may be necessary to manage symptoms and prevent complications.

• Valproic acid: This medication has been shown to be effective in managing seizures associated with macrocephaly (See [8]). It is easily available and inexpensive.
• Antiepileptic drugs: Children with macrocephalic epilepsy may require treatment with antiepileptic medications to control seizures (See [10]).
• Targeted medications: Depending on the underlying cause of the macrocephaly, targeted medications may be used to manage symptoms such as increased intracranial pressure or amblyopia (See [7]).

It's essential to note that the treatment for macrocephaly will vary depending on the diagnosis and underlying cause. In some cases, surgery may be necessary to restore function and improve cosmetic appearance (See [13]). However, in cases of benign familial macrocephaly, no intervention may be needed other than serial monitoring of head size and physical growth (See [2] and [10]).

References:

• [8] Valproic acid can be instituted in macrocephalic children with recurrent generalized seizures.
• [7] Secondary complications should be managed by the appropriate specialists. Targeted medications may be used depending on the underlying cause of the macrocephaly.
• [10] Macrocephalic children with epilepsy may require treatment with antiepileptic drugs.
• [13] Treatment of Macrocephaly... Currently, most cases of macrocephaly are treated surgically with the goal of restoring function and improving cosmetic appearance.

Differential Diagnosis of Macrocephaly

Macrocephaly, or a head circumference above 2 standard deviations, can be caused by various factors. When dealing with an infant or child who has been diagnosed with macrocephaly, it is essential to consider the differential diagnosis to rule out other possible causes.

Common Causes of Macrocephaly

• Benign Enlargement of Subarachnoid Spaces: This is the most common cause of macrocephaly in infancy, with an estimated incidence of 0.5 per 1,000 live births [10].
• Megalencephaly: A developmental disorder characterized by brain overgrowth secondary to increased size and/or numbers of neurons and glia [6].

Rare but Important Disorders

• Greig Cephalopolysyndactyly Syndrome (GCPS): A rare genetic disorder characterized by physical abnormalities affecting the fingers and toes (digits) [8].
• Proteus Syndrome: A disorder of patchy or mosaic postnatal overgrowth of unknown etiology, with an onset typically occurring in infancy [9].

Other Possible Causes

• L2HGA (Leukoencephalopathy with Hypomyelination): A rare genetic disorder that can cause macrocephaly and other neurological symptoms [4].
• Mucopolysaccharidoses: A group of inherited lysosomal storage disorders that can cause macrocephaly and other systemic symptoms [5].

Imaging Modalities

Multiple imaging modalities, including US, CT, and MRI, are complementary in evaluating macrocephaly and can help differentiate between these causes [15].