Copper beaten skull

Description

The human skull has several sutures which separate the bones of the skull but allow the bones to grow in synchrony with the growth of the brain. In the normal case, the sutures close only after the growth of the brain is complete. But if one or other of the sutures close early, this can cause an abnormally shaped skull with or without an increase in the intracranial tension. Premature fusion of sutures (craniosynostosis) can occur in a number of syndromes.¹ One typical manifestation of craniosynostosis is what has come to be described as the ‘copper beaten skull’ appearance. Copper beaten skull is more commonly described in children.^2–5 Here we describe a 24-year-old man who presented to the medicine outpatient (OP) with cough, fever and rhinitis and was incidentally detected to have a copper beaten skull.

A 24-year-old man presented to the medicine OP with 2 weeks history of cough, fever and rhinitis. He was partially treated from outside and the fever had subsided. But he continued to have cough. Physical examination was within normal limits. Posteroanterior chest radiograph was unremarkable. As there was a clinical suspicion of chronic sinusitis, radiograph of the sinuses (Water’s view or occipitomental view) (figure 1A) was also obtained. It did not show any features of chronic sinusitis. This was followed up with an anteroposterior (AP) radiograph of the skull (figure 1B).

Figure 1.

Radiograph of occipitomental view of sinuses (A) and anteroposterior view of skull (B).

Water’s view and AP view show multiple convolution, diffusely distributed on both hemispheres, variously described as beaten silver appearance or copper beaten skull. CT of the brain was also analysed. It did not show any features of intracranial tension or any other intracranial pathology. Also there were no features of ventriculomegaly. CT axial view (figure 2A) shows a scalloped inner table with normal outer table and diploic space. CT three-dimensional surface-shaded display (SSD), axial cut with upper part removed and intracavitary view (figure 2B) shows a scalloped inner table while the outer table appears normal.

Figure 2.

CT of the skull—axial view (A) and intracavitary view (B).

The patient had normal milestones of development in childhood. He was of normal intelligence and could not remember any significant illnesses in childhood. He did not have any dysmorphic features and fundus examination did not show any pappilloedema. He was treated on an OP basis and was asymptomatic within 1 week of follow-up. Copper beaten skull was an incidental finding in the patient.

In infants and young children pulsations from the rapidly growing brain can produce markings on the inner table of the skull forming a peculiar pattern, variously described as beaten silver appearance or, more commonly, copper beaten appearance. These markings are noticed by depressions corresponding to the brain gyri and thicker intervening bony ridges corresponding to cerebral sulci. These markings may be first seen at 1 year of age with an increased incidence during the period of rapid brain expansion in the first 3 years of life.⁶ Currently this pattern is considered to be a manifestation of normal brain growth and becomes less prominent after 8 years of life.⁴ These are usually confined to the posterior part of the skull’s inner table. Besides the sensitivity of radiological methods for detecting elevated intracranial pressure (ICP) is universally low, these methods are not recommended to screen for elevated ICP in children with craniosynostosis.⁷

When a diffuse and severe copper beaten appearance is seen, especially in an older person, increased ICP should be ruled out. Associated conditions including craniosynostosis, obstructive hydrocephalus and intracranial mass should be looked for.⁴

Copper beaten appearance in an adult with no evidence of raised ICP is a rare entity. Our patient was one such subject.

Learning points.

• When a diffuse and severe ‘copper beaten appearance’ of the skull is seen, intracranial pressure (ICP) should be ruled out first. If there is a strong clinical suspicion of raised ICP, lumbar puncture with precautions can be considered to measure cerebrospinal fluid pressure.

• Copper beaten appearance of the skull in an older patient need not necessarily be a manifestation of raised ICP. Sometimes it could be a normal variant as was in this case.