Post hair transplant scalp arteriovenous fistula: A case illustration with a collective review

INTRODUCTION

With over 1.2 billion people affected by male pattern baldness, hair transplantation is widely regarded as the leading cosmetic procedure among men, with more than 735,000 transplants performed globally each year.^[1-3] Although hair transplant techniques and expertise have significantly advanced since their initial documentation over a century ago, reports of vascular complications related to these procedures remain rare.^[4-8] Post hair transplant scalp arteriovenous malformation (AVM), often referred to as a cirsoid aneurysm, indicates the abnormal connection that develops between the arterial supply to the scalp and the draining veins, effectively bypassing the intermediate capillary bed.^[9] If untreated for an extended period, scalp AVM can lead to severe neurological consequences, including acute intracranial hemorrhage, seizures, and significant neurological deficits, and may, in rare cases, result in death.^[10-25] Following a thorough manual literature search, we have compiled 18 previously published reports on post hair transplant scalp AVM to date [Table 1]. This report aims to present our case while conducting a comprehensive review of all previously reported cases, with special attention to their clinical presentation, relationship with hair transplant techniques, neurodiagnostic features, and treatment options prognosis.

CASE REPORT

A 31-year-old male initially presented 5 years ago with complaints of a throbbing headache and a pulsatile mass in the left frontotemporal region. Two years before this presentation, he underwent hair transplantation utilizing the follicular unit transplantation (FUT) technique. He reported swelling on the left side of his forehead just two weeks post hair transplantation, which progressively enlarged. His neurological examination was essentially unremarkable, while the local examination revealed a palpable bruit in the swollen scalp area, accompanied by prominent scalp vessels primarily on the left side of the head. He subsequently underwent magnetic resonance (MR) imaging (MRI) of the head with MR angiography [Figure 1]. This illustrated a left frontal scalp AVM characterized by multiple tortuous flow voids and dilated feeding and draining vessels. The left superior ophthalmic vein was also noted to be dilated. The primary feeding arteries originated from the dilated, tortuous left superficial temporal artery (STA), with drainage occurring through the dilated left facial vein. In addition, contralateral supply from the right external carotid artery and facial veins was observed. These findings correspond to a scalp AVM, also referred to as a cirsoid aneurysm of the scalp.

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Figure 1:

(a and b) Magnetic resonance images (MRI) with contrast in axial and sagittal planes show a left frontotemporal vascular malformation in the scalp. (c) Magnetic resonance angiography (MRA) with 3D reconstruction displays the predominant left superficial temporal artery (green arrow), the fistulous point (yellow arrow), and the dilated vein drainage (white arrow).

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His catheter cerebral angiography [Figure 2] showed a scalp AVM in the left anterior frontal area, predominantly supplied by the hypertrophied left STA, which appeared markedly tortuous and ended in a dilated venous pouch draining anteriorly into the left angular vein, both facial veins, and posteriorly into multiple superficial scalp veins. Numerous arterial feeders were identified, originating from the contralateral external carotid artery and the left ophthalmic artery. This was achieved through their anastomosis with the supraorbital and supratrochlear branches. The findings are consistent with a diagnosis of a scalp arteriovenous fistula (AVF) characterized by multiple feeding arteries bilaterally and superficial draining veins in the scalp, with no identified connections to the cerebral vasculature.

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Figure 2:

(a and b) Pre-operative cerebral angiography of the selective left external carotid artery in the frontal and lateral planes shows predominant feeders from the left superficial temporal artery (STA) (green arrow), a fistulous point (yellow arrow), and dilated draining veins (white arrows). (c) There are supplementary feeding arteries contributed by the contralateral STA, which fill the draining veins.

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The patient was offered various treatment options, including endovascular embolization and surgical excision. However, he declined all forms of treatment and was subsequently lost to follow-up. Upon his return visit, the patient exhibited a recurrence of worsening headaches, an increase in scalp swelling, and a single episode of recent epistaxis. He subsequently underwent repeat MRI, including MR and catheter cerebral angiography. The evaluation of the scalp AVM demonstrated a similar angioarchitecture, with the nidus increasing in size to 2.3 × 1.5 cm compared to the previous measurement of 1.7 × 1.4 cm recorded 5 years ago.

A multidisciplinary team (including neurosurgeons, neurointerventionists, plastic surgeons, and radiation oncologists) discussed the case in our fortnightly meeting regarding the treatment choice. They concluded that vascular malformation was not feasible for endovascular or percutaneous embolization due to its high-flow fistulous connections and tortuous angioarchitecture. A consensus decision was made to proceed with surgical excision with intraoperative cerebral angiography. The patient underwent surgery in a hybrid operating room (Brainsuite®, California, USA) equipped with an intraoperative 3D cerebral angiography suite (Artis Zeego®, Siemens Healthcare GmbH, Germany). After being positioned supine, the patient underwent cerebral angiography, and the fistulous point was localized using a laser grid integrated into the angiography gantry. Following the surgical excision, a femoral angiography sheath was left in situ for subsequent intraoperative angiography. A 6 cm curvilinear incision was made just posterior to the localized fistula in the coronal plane. Abnormally dilated, easily identifiable vessels were progressively coagulated as the skin incision was enlarged.

The main dilated vein was carefully dissected; the AVF was skeletonized and exposed. Afferent and efferent vessels to the AVF were coagulated. Two straight titanium Sugita® aneurysm clips (Mizuho Medical Co. Ltd, Tokyo, Japan) were placed on the STA before disconnecting. Then, the AVF was dissected from the deep surface of the reflected flap, above the temporal muscle, between the epicranial aponeurosis (galea aponeurotica) and the subcutaneous fat. The AVF was removed entirely without needing to remove the overlying skin. Before closing the wound, a post-excision intraoperative cerebral angiography [Figure 3a and b] was performed to ensure the complete excision of the fistulous nidus. Subsequently, the surgical flap was replaced and sutured. Blood loss was minimal, estimated at <150 mL, due to progressive vessel dissection and meticulous coagulation. Histopathology of excised tissue confirmed the diagnosis of AVM.

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Figure 3:

(a and b) Intraoperative cerebral angiography pre- and post-excision of the fistulous nidus in lateral views shows no perfused nidus or draining veins. (c and d) Post-operative gadolinium-enhanced magnetic resonance imaging of the head after 8 weeks shows no residual or recurrence of the scalp arteriovenous malformation.

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Postoperatively, the patient recovered completely with no symptoms. At the 3-month follow-up, he had fully recovered, with a well-healed surgical wound, no scalp necrosis, and the complete disappearance of prominent blood vessels on the scalp. A follow-up MRI [Figure 3c and d] of the head and MR angiography confirmed complete surgical excision.

DISCUSSION

The origins of successful hair transplantation trace back to as early as 1804 when Baromio conducted animal experiments. However, Okuda first documented the autologous hair transplantation technique in humans during the 1930s.^[26-28] Since then, innovative techniques have transformed esthetic outcomes and enhanced safety profiles, with an overall complication rate ranging from 3% to 5%.^{[2,3,6,8,29,30]} Notably, prominent studies on complications associated with hair transplants have not reported a single case of vascular complications, including scalp AVMs.^[4-8] With advancements and refinements in endovascular and microsurgical techniques, there is renewed interest in scalp fistulae, particularly those that develop after hair transplantation.^[9,30]

CONCLUSION

Post hair transplantation AVFs are extremely rare; however, they can lead to significant complications. Clinical manifestations may be delayed several years after hair transplantation, necessitating timely diagnosis and appropriate imaging if suspected. Surgical excision has traditionally been the primary treatment option. However, there is a gradual shift in paradigm toward endovascular and/or percutaneous embolization in select cases, demonstrating satisfactory prognoses regardless of the treatment method used. Therefore, it is advisable to incorporate the potential for developing this rare yet serious vascular complication in the counseling process for this most commonly performed aesthetic procedure for male hair restoration.