Long-term Effect of Cranioplasty on Overlying Scalp Atrophy

Abstract

Scalp thinning over a cranioplasty can lead to complex wound problems, such as extrusion and infection. However, the details of this process remain unknown. The aim of this study was to describe long-term soft-tissue changes over various cranioplasty materials and to examine risk factors associated with accelerated scalp thinning.

Methods: A retrospective review of patients treated with isolated cranioplasty between 2003 and 2015 was conducted. To limit confounders, patients with additional scalp reconstruction or who had a radiologic follow-up for less than 1 year were excluded. Computed tomography or magnetic resonance imaging was used to measure scalp thickness in identical locations and on the mirror image side of the scalp at different time points.

Results: One hundred one patients treated with autogenous bone (N = 38), polymethylmethacrylate (N = 33), and titanium mesh (N = 30) were identified. Mean skull defect size was 104.6 ± 43.8 cm². Mean length of follow-up was 5.6 ± 2.6 years. Significant thinning of the scalp occurred over all materials (P < 0.05). This was most notable over the first 2 years after reconstruction. Risk factors included the use of titanium mesh (P < 0.05), use of radiation (P < 0.05), reconstruction in temporal location (P < 0.05), and use of a T-shaped or "question mark" incision (P < 0.05).

Conclusions: Thinning of the native scalp occurred over both autogenous and alloplastic materials. This process was more severe and more progressive when titanium mesh was used. In our group of patients without preexisting soft-tissue problems, native scalp atrophy rarely led to implant exposure. Other risk factors for scalp atrophy included radiation, temporal location, and type of surgical exposure.

Fig. 1.

A 63-year-old woman with history of intracranial tumor excision and irradiation who presented 2 years later with progressive scalp thinning and extrusion of a prominent plate used for fixing the autogenous bone flap. A, Plate extrusion can be seen over the midline location. B, A three-dimensional (3D) computed tomographic image showing the size and location of the cranial reconstruction.

Fig. 2.

A 45-year-old woman with history of intracranial tumor excision and titanium mesh cranioplasty. Considerable thinning of the scalp occurred over the mesh 1 year after reconstruction, leading to extrusion A, Photograph of the patient’s head 1 year after surgery. B, Close-up of scalp thinning with implant exposure. C, A three-dimensional (3D) computed tomographic image showing the size and location of cranial reconstruction.

Fig. 3.

Selection of patients for the study.

Fig. 4.

Graph showing scalp thinning over cranioplasty material with time (all materials studied). The red line depicts percent scalp thinning when scalp over the reconstruction is compared with the preoperative scalp thickness in the same location. The green line compares percent scalp thickness when the scalp over the reconstruction is compared with the mirror image scalp at the same time periods.

Fig. 5.

Graph showing relative scalp thickness changes over different cranioplasty materials. Scalp atrophy is most evident during the first 2 years after reconstruction. Scalp over autogenous bone and polymethylmethacrylate thins during the first 2 years after reconstruction and then remains relatively stable. Scalp atrophy over titanium mesh is most evident during the first 2 years but continues to progress over time unlike other materials.