Scalp reconstruction is a surgical procedure for people with scalp defects. Scalp defects may be partial or full thickness and can be congenital or acquired. Because not all layers of the scalp are elastic and the scalp has a convex shape, the use of primary closure is limited. Sometimes the easiest way of closing the wound may not be the ideal or best way. The choice for a reconstruction depends on multiple factors, such as the defect itself, the patient characteristics and surgeon preference.
History
Skull and brain 'surgery' are known from the prehistoric era. There is evidence of scalp reconstructions dating back to the Egyptians in 3000 BC, and to the Roman Empire. The word plastic surgery likely comes from the Greek πλαστικός (plastikós lit. "formable", "mouldable"). Attempts were made to reconstruct damaged skulls despite minimal knowledge of neurology, anatomy, and the brain. Skulls showing manipulation that can be interpreted as a primitive form of surgery have been found from various eras around the world. In medieval times, people were convinced that trepanation was a remedy for various diseases.
Indications Main reasons for scalp reconstruction are divided into two groups: congenital or acquired. Congenital defects may include aplasia cutis congenita, congenital nevus, congenital vascular malformations and congenital tumors. Acquired defects can be caused by burns, blunt, penetrating, or avulsion injuries, tumor invasion, infection, oncologic resection, radiation, or wound-healing difficulties. Alopecia can be an aesthetic motivation for hair-bearing scalp reconstruction. As the incidence of basal-cell carcinoma and squamous-cell carcinoma is rising and about 80% are located in the head and neck area, the number of scalp reconstructions will likely increase in the future. Depending on the size and nature of the defect, an appropriate reconstructive method has to be used. By using Mohs surgery the defect can be kept minimal, but nevertheless infiltrative basal-cell carcinoma may have the need to remove a large part of the scalp. On the flowchart, a simplified algorithm for scalp reconstruction is depicted. The options range from simple solutions for small skin defects to complicated reconstructions requiring multi-tissue reconstructions. An active and severe infection must be controlled first by surgical debridement and antibiotic treatment before reconstruction is performed, as infection can cause bacteraemia and has a negative effect on wound healing.
Surgical anatomy The five layers of the scalp, from superficial to deep, can be memorized by using the mnemonic SCALP. The Skin of the scalp has been scientifically examined for thickness. The posterior scalp skin thickness is 1.48 mm; the temporal scalp is 1.38mm; and the anterior scalp thickness is 1.18 mm. The scalp contains approximately 100.000 hairs. Hair lines make scalp reconstruction difficult because the hair lines must be respected to attain a satisfying aesthetic result. The subCutis is a layer of fat, enclosed in compartments formed by rigid fibrous septa. Their inelasticity prevents bleeding vessels from collapsing and retracting under the skin to achieve haemostasis. All large blood vessels and nerves of the scalp are located in this layer. The next layer is the galea Aponeurotica, which separates the underlying bone and the overlying layers. The large blood vessels and nerves of the scalp do not pierce this layer. Loose connective tissue between the periosteum and the aponeurosis makes these two rigid structures easily slide over each other and contribute to skin movement. Thus, if vascular and nervous anatomy is respected, the skin, subcutaneous tissue and galea aponeurotica can be lifted off the skull with minimal bleeding, nerve damage, or chance of necrosis. This method was first described by Orticochea in 1967, but has been updated to minimize scarring. The fifth layer is the Periosteum of the skull, also referred to as pericranium. It can be separated from the skull, except near the sutures. The skull consists of an inner and outer table, with spongy bone in between known as diploë.
Vascular supply On both sides of the scalp, there are five large arteries that perfuse the scalp. Local flaps used for scalp reconstruction must contain at least one of these major arteries, to maintain a reliable blood supply. The scalp can be divided into four different vascular territories:
Anterior: supratrochlear artery and supraorbital artery Lateral: superficial temporal artery Posterior: occipital artery Posterolateral: posterior auricular artery
The veins anastomose frequently with each other and enter the diploic veins of the skull bones and the dural sinuses. This is an extra difficulty as the vein pattern differs. The scalp veins accompany the arteries and have similar names:
Anterior: Supratrochlear vein and supraorbital vein Lateral: Superficial temporal vein Posterior: Occipital vein Posterolateral: Posterior auricular vein
Lymphatic system The frontal part of the scalp is drained to the parotid, submandibular, and deep cervical lymph nodes. The posterior part is drained to the posterior auricular and occipital lymph nodes. Malignancies of the scalp can metastasize to these lymph nodes. Brain tumors, however, tend to metastasize haematogenously (through the blood).
Innervation The scalp is innervated by motor nerves and sensory nerves. The trigeminal nerve (CNV) is one of the important cranial sensory nerves which innervates the scalp. From anterior to posterior front to back the nerves are:
Supratrochlear nerve and Supraorbital nerve Zygomaticotemporal nerve Auriculotemporal nerve Lesser occipital nerve Greater occipital nerve
Non-skin reconstruction
Dura mater reconstruction Dural lesions should be closed to avoid CSF leakage. Also, a defect acts like a port of entry for micro-organisms that can cause meningitis. If fibrin glue or primary closure is not possible, patches have to be used. These are made from cadaveric dura mater, xenografts (tachosil, duragen, durepair), or synthetic grafts materials (PTFE, neuropatch). However, (vascularised) autografts (fascia lata, muscle or omentum majus) are preferred in irradiated or severely infected defects.
Bone defects
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