Craniolacunia

At a glance

A transitory disease characterized by punched-out skull defects.

Synonyms

Lacunar Skull; Fenestrated Skull; Lückenschädel (which is the correct German spelling).

Incidence

Unknown.

Genetic inheritance

Unknown. One case report described FGFR2 (Fibroblast Growth Factor Receptor 2) gene mutations in an infant girl with craniolacunia.

Diagnosis

Based on the clinical and radiological findings. On conventional x-ray, craniolacunia has a characteristic honeycomb appearance, with large rounded areas of decreased bone density bordered by a web-like pattern of thicker bone. However, the bone pathology is best appreciated by CT-scanning with three-dimensional reconstruction that clearly reveals the abnormal bone structure.

Clinical aspects

Craniolacunia is considered a mesenchymal dysplasia affecting the calvarial ossification. The lesions involve the inner table of the membranous portion of the skull and the diploe (and less frequently include the outer table) and appear as multiple, “punched-out”, round-oval, or elongated skull defects with a diameter of up to 1 cm and well-defined borders, separated by bony trabecular ridges. Strictly taken, craniolacunia refers to defects that involve only the inner table of bone and are not palpable from outside, whereas craniofenestrae describes full thickness involvement of the calvaria with the inner and outer table affected and are therefore palpable on clinical examination. Craniolacunia may be an isolated finding; however, it is most often associated with neural tube defects, such as spina bifida, myelomeningocele, and encephalocele, or with other cerebral lesions like hydrocephalus and ☞Arnold-Chiari Syndrome Type II, or with ☞Klippel-Feil Syndrome. The exact etiology of the defects is unknown; however, one suggestion involves the lack of cerebral ventricular distension due to a neural tube defect, which in turn leads to a lack of fetal brain distension that would be required to induce normal development and growth of the membranous plates of the fetal calvaria. Instead, abnormally organized collagen fibers are produced and their ossification results in the defects seen in craniolacunia. Early radiologic case series reported an incidence of up to 60% of Lückenschädel in neonates born with neural tube defects, with a higher incidence in more severe lesions. CT-scanning in newborns or infants with meningomyelocele detects signs of craniolacunia in up to 92%. The fact that most defects resolve by 6 months of age has been explained with remodeling in response to either normal expansion of cerebral tissue or development of hydrocephalus. The most commonly affected bones are the parietal and occipital bones. Generally, craniolacunia is not associated with increased intracranial pressure (ICP) and appears not to affect neurologic outcome, if the accompanying lesions can be well managed.

Precautions before anesthesia

Assess the size and location of the calvarial defects (x-ray, CT-scans) to know which areas of the skull need protection from direct ...