Surgical management of scalp arterio-venous malformation and scalp venous malformation: An experience of eleven cases.

AIMS: Scalp arterio-venous malformation (AVM) and scalp venous malformation (SVM) are rare conditions that usually need surgical treatment. Here, we have reported our experience of the surgical management of such lesions with a short review of the literature.
MATERIALS AND METHODS: In this prospective study, 11 patients with scalp AVM and SVM, who underwent surgical excision of lesion in our hospital from 2006 to 2012, were included. All suspected high-flow AVM were investigated with the selective internal and external carotid digital subtraction angiogram (DSA) ± computed tomography (CT) scan of brain with CT angiogram or magnetic resonance imaging (MRI) of brain with MR angiogram, and all suspected low-flow vascular malformation (VM) was investigated with MRI of brain + MR angiogram. Eight were high-flow and three were low-flow VM.
RESULTS: All lesions were successfully excised. Scalp cosmetic aspects were acceptable in all cases. There was no major post-operative complication or recurrence till last follow-up.
CONCLUSIONS: With preoperative appropriate surgical planning, scalp AVM and SVM can be excised without major complication.

INTRODUCTION

An arterio-venous malformation (AVM) is an abnormal fistulous connection between the feeding arteries and draining veins, without an intervening capillary bed within the subcutaneous layer.[12] Its management is difficult because of its complex vascular anatomy, high-shunt flow (in high-flow AVM), intracranial connection (when present) and possible cosmetic complications.[345] They are relatively rare vascular lesions present as an subcutaneous scalp lump or a large, pulsatile mass with a propensity to skin erosion and massive haemorrhage.[67] Several treatment options that have been described to treat these lesions, including surgical excision,[2689] ligation of feeding vessels, transarterial and transvenous embolization,[81011] injection of sclerosant into the nidus[1213] and electro thrombosis.[1415] Here, we have described our experiences of surgical management of scalp VM (SVM) and result along with a short literature review.

MATERIALS AND METHODS

Eleven patients with scalp AVM and SVM who underwent surgical excision of lesion in Dhaka Medical College Hospital and few private hospitals in Dhaka, Bangladesh from 2006 to 2012 were included. All clinical data, investigations, surgical procedures and postoperative follow-up were recorded and studied prospectively. All suspected high-flow AVM were investigated with the selective internal and external carotid digital subtraction angiogram (DSA) ± computed tomography (CT) scan of brain with CT angiogram or magnetic resonance imaging (MRI) of brain with MR angiogram, and all suspected low-flow vascular malformation (VM) was investigated with MRI of brain + MR angiogram. Eight were high-flow lesions and three were low-flow VM. No scale or criteria was used for the assessment of cosmetic appearance other than patient's own and his/her relatives’ appreciation of the final appearance (excellent, good, acceptable or not acceptable). Average follow-up was 3.6 years (6 months to 6.5 years).

Surgical treatment

The patient was positioned according to the site of lesion with the head elevated 20-30° above the level of the heart. The scalp flap was made according to the anatomy of the AVM and VM, and the direction of the feeding arteries and draining veins. In very high-flow AVMs, proximal control of external carotid artery was obtained prior to scalp surgery. The feeding arteries were preserved at the base of the scalp flap, and the flap incorporated one or more normal non-feeding vessels so as not to jeopardize its vascularity. The skin incision line was infiltrated adequately with lignocaine with adrenaline (1:100000 strength) only in low-flow SVM. The scalp was incised in short segments with careful haemostasis using haemostatic forceps and bipolar coagulation. The scalp flap was raised along with the pericranium. The bleeding from the bone was controlled with bone wax and monopolar diathermy. The feeding arteries were identified along their course at the base of the scalp flap, the pericranium and galea were incised, the vessels were traced distally towards the nidus of the scalp malformations, ligated, and/or coagulated and then divided. As the feeding vessels were ligated, the VM was devascularized. The pericranium and the galea were circumferentially incised, and the VM was excised. Where there was unavoidable skin loss with the excised lesion, wound was closed multiple galeal incisions and scalp mobilization and/or rotational flaps.

RESULTS

Among the 11 cases as seen in Table 1 [Figures 1-11] eight were high-flow AVM and three were low-flow SVM (two cavernoma and one venous malformation-sinus pericranii). Age rang was 04 months to 72 years. Four were female and seven were male. Commonly involved areas were frontal, parietal and temporal. More than one area was involved in four cases. Only two patients had history of trauma, and two patients had history of prior surgery for their lesions. In five patients, the AVM extended on the both side of midline. Common clinical features were swelling, headache, skin changes and recurrent bleeding. Common feeders were superficial temporal, supraorbital and occipital artery. There was no supply to AVM from MCA, Anterior cerebral (ACA) or vertebro-basilar system. In one case (case 5), there was some intracranial venous communication. In case 2, sinus pericranii was connected with superior sagital sinus (SSS). Per-operative bleeding was not a problem in ten cases where blood transfusion was one unit or less. In case 5, three unit blood was required due to external carotid artery (ECA) partial rupture and intracranial venous communication. Complete excision was done satisfactorily in all cases without any recurrence until the last follow-up. Minor infection occurred in one case (case 5), and wound infection and wound dehiscence occurred in two cases. In case 7, wound infection and dehiscence were managed conservatively with antibiotic and regular dressing. In case 10, the dehiscence was very big, and a second operation was needed to close it with local scalp rotational flap. Excellent cosmetic result was observed in nine cases. In two cases, wound healing was acceptable with scar formation in hairy area. We faced no brain oedema or intracranial hematoma after operation. There were no recurrence in any case until the last follow-up.

Table 1

Details of all cases

Figure 1

(a) Per-operative picture of lesion. (b) Post-operative picture of patient

Figure 11

(a and b) Post-AVM excisional wound infection and large wound gap. (c and d) Pictures of wound 12 day after second operation (wound closure by rotational flap of scalp). (e and f) Pictures 1 year after operation showing acceptable cosmetic outcome

(a and b) CTA of extracranial vessel showing left posterior parietal AVM with feeder from superficial temporal and occipital artery

Peroperative picture of temporal cavernoma

(a and b) Pre-operative picture of patient and lesion. (c) CT scan of head showing extracranial lesion. (d) Per-opeartive picture after complete removal of low-flow vascular malformation

(a) Pre-operative picture of lesion and patient. (b and c) Immediate pre-operative picture of lesion. (d) Post-operative picture of operating site with infection. (e and f) Post-operative picture of patient with ultimate outcome of operating site 2.5 months after operation

Representative cases

Case 2

An 8-month-old male child presented with a 9 × 11 cm swelling in mid-frontal region extending more to the right up to the supra-orbital region. Swelling increased in size during cry and prone position of the baby, and it was compressible and non pulsatile. There was no other prominent vessel on face and scalp. The right orbit was a little downward and outward placed. Right half of his face was little hypoplastic. CT scan of brain showed extra-calvarial soft tissue mass in frontal region, and there was no apparent bony gap infront of anterior fontanel. CT angiogram showed soft tissue mass was vascular lesion connected with SSS through emissary veins and intracranial dural sinuses including SSS were normal. There were no prominent veins of face or scalp connected with vascular lesion. The lesion was excised completely by elevation of a bi-frontal flap through a post-hairline bi-coronal incision. Connecting emissary veins were coagulated and cut to remove the lesion. The lesion was well-defined capsulated without septation and filled with venous blood. Histopathology reported venous malformation-sinus pericranii. The patient recovered uneventfully (Figures 2 and 3) and has remained asymptomatic for last 5 years (until the last follow-up).

Figure 2

(a and b) Pre-operative picture of lesion and patient. (c and d) Post-operative picture patient with good cosmetic outcome

Figure 3

(a and b) CTA of head showing frontal venous malformation (sinus pericranii) with normal intracranial venous sinuses. (c) Per-operative picture of low-flow lesion after exposure. (d) Per-operative picture after complete excision of lesion

Case 5

A 43-years-old male patient presented with right-sided pulsatile, progressively increasing fronto-parieto-temporal swelling measuring about 15 × 19 cm. He had headache and tinnitus. The swelling was diffusely serpentine. There was skin changes (ulceration and healed ulcerated areas). He had a history of surgery 5 years back in another institution. According to the patient, the lesion progressively increased in size after the operation. He also had recurrent attack of haemorrhage from the ulcerated area but none were of serious nature to cause shock and were controlled by pressure dressings. CT scan showed large soft tissue swelling [Figure 6] and the bony windows showed multiple erosions and prominent vascular marking. Right-sided common carotid artery and ECA angiogram showed huge dilatation of branches (occipital artery, posterior auricular artery, superficial temporal artery and maxillary artery and its branches, including meningeal and middle temporal arteries) of ECA supplying the AVM. Left ECA angiogram showed enlargement and tortuousity of left occipital, posterior auricular and superficial temporal arteries supplying the AVM crossing the midline. Both internal carotid artery (ICA) angiograms showed prominent ophthalmic and supraorbital and supratrochlear arteries supplying the AVM. ACA, middle cerebral (MCA) and vertebro-basilar arterial systems were normal and intracranial venous drainage system seemed to be normal [Figure 7]. Right-sided ECA was ligated at the beginning of operation through a neck incision (During ligation, partial rupture of ECA occurred, which was immediately controlled). Then, AVM was excised completely with some part of skin (ulcerated and infected area). At the posterior part of AVM, there was some intracranial venous connection through bony erosion. There was also some significant pericranial component of AVM. Wound was closed with a transposition scalp flap. Postoperatively, there was minor wound infection that was controlled by regular dressing and antibiotic. Cosmetic appearance improved after 2 months [Figure 8]. The patient has remained free of recurrence of AVM for last 1.5 years (until the last follow-up).

Figure 6

(a and b) CT scan of head showing huge diffuse extracranial soft tissue swelling and multiple vascular marking (guttering and erosion by AVM vessels)

Figure 7

(a-i) DSA of ECA and internal carotid artery (ICA) showing bilateral feeding vessels from branches of ECA and ICA through supratrochlear and supraorbital arteries. There was aneurysmic and ecstatic dilatation of right ECA and its branches

Figure 8

(a-c) Immediate pre-operative picture of AVM. (d-f) Immediate post-operative picture of operative site. (g and h) Post-operative picture of 9th post-operative day. (i) Post-operative picture 4 week after operation with good cosmetic outcome

DISCUSSION

The scalp AVM is an abnormal arteriovenous communication situated within the subcutaneous fatty layer of the scalp. In low-flow VM (i.e., cavernoma, cavernous hemangioma, venous malformation and sinus pericranii), usually, no arteriovenous shunt is present and they are seen as well-demarcated lesions.[11516] The origin of AVM of the scalp is still uncertain, but trauma is an important factor in most of the patients,[35] though some are congenital (spontaneous) in origin.[6] The post traumatic ones generally develop in patients over 30 years of age. Spontaneous AVM of the scalp may present at birth, but, in most patients, it is asymptomatic until adulthood.[31617] Low-flow VM or SVM are usually congenital in nature. Trauma, pregnancy or hormonal change causes deterioration of the symptoms. Traumatic AVM of the scalp develops months or years after the scalp trauma. About 10-20% of scalp AVMs develop following penetrating or non-penetrating trauma to the scalp.[151618] They are equally distributed in the frontal, parietal and temporal areas.[6] Various names being used to describe the VMs of the scalp include aneurysm cirsoide, aneurysma serpentinum, aneurysm racemosum, plexiform angioma, arteriovenous fistula and AVM.[51920] The origin of the main feeding arteries is in the subcutaneous tissue of the scalp. The origin of these main feeders, most frequently, arises from the external carotid, occipital and supraorbital arteries. The STA is frequently involved in traumatic cirsoid aneurysm.[182122] In this series, two patients had blunt injury to the head. However, these patients noticed the swelling many years later. Most of the patients had a history of progressive increase in the size of the lesion and had become symptomatic in the third decade of life.[220] Their clinical features are associated with the size of the AVM. The patients may present with a pulsatile mass, headache, local pain, tinitus, numbness, necrosis, ulcer and/or haemorrhage.[32122] Patients with high flow lesions also present with loud bruit.[10] Haemorrhage is generally uncommon and may develop in the event of large VMs. Recurrent haemorrhage, from necrotic areas may be seen in some patients.[1316] Three patients in this series had recurrent haemorrhage from their lesions. Angiography is the gold standard investigation to delineate the lesion and to exclude an intracranial component;[15] it is of great importance for diagnosis and treatment selection. It is particularly employed for the determination of cranial feeders. Selective angiography should be carried out for differential diagnosis of the vascular lesions, such as aneurysms, sinus pericranii, venous malformation and cavernous hemangioma.[21516] Brain MRI is also of significance for establishing the diagnosis. Scalp high-flow AVMs are needed to differentiate from low-flow AVMS as the latter are more susceptible to sclerotherapy. AVMs show flow void signs on MRI due to the rapid flow in the lesions.[141516]

Management of scalp AVM is difficult because of its high shunt flow, intracranial communication, complex vascular anatomy and cosmetic problems. When sinus pericranii or venous malformation associated with intracranial sinus occlusion or congenital absence of sinus, then treatment become difficult. The indication of treatment includes cosmetic relief of the pulsatile or non-pulsatile mass, prevention of haemorrhage and other symptoms such as headache and tinnitus. The treatment options include surgical excision[26789] ligation of feeding vessels, transarterial and transvenous embolization,[381011] injection of sclerosant into the nidus[89] and electro thrombosis.[1423]

Surgical excision is the most common and successful method of dealing with scalp vascular lesion.[1313] Surgical treatment is particularly indicated in order to rule out bleeding and for the resolution of cosmetic problems, as well as treat the accompaning issues of tinnitus and headache.[51821] AVM is generally located in the periosteal and temporal fascia or under the galea. Thus, pre-operative radiological evaluation should be used for the assessment of feeding arteries, drainage vessels, numbers of fistulas, connected vascular structures and shunt flow volume in order to prevent any possible complications.[31823]

Various techniques have been used to control the haemorrhage during surgery including percutaneous sutures of the feeding vessels,[3] interlocking suture along the line of incision and use of tourniquet and intestinal clamp over the base of the flap.[22] A step-wise incision with careful pressure control is a useful method to control the scalp bleeding.[6] Reflection of the pericranium along with the scalp flap prevents inadvertent rupture of the nidus. In AVM, there may be significant pericranial component of the malformation[6] as was evident in one of our cases.

Due to the anomalous arteriovenous communication, AVM must be completely eliminated because recurrence or enlargement is reported after an incomplete treatment.[920]

Infection, sepsis, haemorrhage and necrosis may occur as complications.[11523] Endovascular treatment may be applied in order to decrease the haemorrhage and facilitate the surgical treatment or in the direct treatment of AVMs.[51824] Pre operative embolization of nidus and feeders especially prevents massive haemorrhage. Embolization of both feeders and nidus before surgery is safer than embolization of the feeders alone to reduce the risk of excessive haemorrhage.[8] Three different approaches have been used to access the fistula, namely femoral transarterial, femoral transvenous and direct percutaneous catheterization of the feeding arteries or draining veins.[810111323] Direct percutaneous catheterization of the fistula has been used whenever access through the artery or vein was not possible.[10] The percutaneous placement of thrombogenic coils is a simple and effective method to produce thrombosis of cirsoid aneurysm of the scalp, especially after slowing down the blood flow through transvascular intra-arterial embolization.[15]

Embolization and endovascular treatment may not be sufficient in the treatment of large scalp AVMs. Incomplete surgical resection is also insufficient for the treatment. This may cause scalp haemorrhage and necrosis, especially in elderly patients.[151618] Due to feeding collaterals, recurrence is possible even after a long time. The most important step is total surgical excision without causing scalp necrosis and excessive blood loss. Furthermore, in this way, a better cosmetic result may be obtained.[1315]

The low- and high-flow scalp AVMs have different management protocol. A thorough clinical evaluation for differentiation of high-flow malformation from low-flow, should be followed by either a CT angiogram or MR angiogram and/or DSA. A high-flow AVM with large size, multiple feeders, skin changes, skin necrosis/ulceration and haemorrhage are the right candidate for surgical treatment as it gives best chances of cure with better cosmetic result and less chance of recurrence. Feeding arteries should be identified clinically and confirmed by imaging. Appropriate management plan should be made on the basis of clinical data, investigation findings, available treatment options (surgery, embolization + surgery or embolization alone) and surgical expertise. In scalp AVM, usually there are multiple feeders, even with single feeder cure without recurrence is probably rare. Moreover, per-operative feeder control is very easy for a skilled surgeon even if it needs a separate incision. The scalp flap should be planned in such a way that the feeding arteries are preserved in the base of the scalp flap and the flap incorporate one or more normal non-feeding vessels so as not to jeopardize the flap blood supply once the feeding vessels are ligated. In case of unavoidable skin excision with AVM, one should keep option/s for scalp reconstruction. The scalp incision should be in short segments with appropriate haemostasis. The flap should be raised along with the pericranium, the feeders should be identified, the pericranium and galea incised, the vessels traced distally towards the nidus and ligated, and/or coagulated and divided. The pericranium and the galea should be circumferentially incised for excision of AVM. Wherever needed, scalp should be reconstructed with scalp mobilization or rotational flap.

In the management of low-flow VM patient age, size of lesion, presenting complains, skin thickness and intracranial venous sinus communication with direction of venous blood flow are important factors. In our series, among the three low-flow VMs, two were under 1 year of age with a large lesion and the skin overlying the lesion was thin. In one case, scalp lesion was connected with superior saggital sinus. In the remaining case, patient wanted removal of mass. Due to possible intracranial complications, and chances of scalp necrosis, bleeding, ulceration, and scarring and other systemic complication, we did not use interventional radiology or sclerosants in our series but with expert interventional radiologists these are very valuable tools of management of such lesions.

CONCLUSION

With pre-operative appropriate surgical planning, scalp AVM and SVM can be excised safely without any major complication. Though some cases may be treated with percutaneus or endovascular embolization, surgery remains the mainstay of treatment. In the event of scalp ulceration and haemorrhage, total excision is the only option. CT/MR angiography and/or DSA helps us to differentiate between low flow and high flow lesions as well as identify the feeders and the nidus.