Cranial head holders provide rigid fixation of the calvarium for assistance in instrumented fusion and complex cranial procedures. The Mayfield skull clamp (Integra LifeSciences Corporation, Plainsboro Center, New Jersey) is commonly used. Direct complications from this skull clamp are rare but can incur notable morbidity and mortality without early recognition. Reported complications after skull clamp placement include pin slippage, epidural hematoma,1,2 depressed skull fractures,3 dural lacerations, air embolism,4,5 traumatic cerebral spinal fluid leaks,6 wound infections, traumatic superficial temporal artery aneurysm, and middle meningeal arteriovenous fistula.7 Demiroz et al8 reported an injury to the facial nerve during prone positioning during a spinal procedure that resolved after a course of oral steroids and physical therapy. The authors are not aware of a peripheral facial nerve injury related to Mayfield clamp placement.
The course of cranial nerve VII, the facial nerve, is at risk during procedures because of its subcutaneous course, particularly at the lateral border of the frontalis muscle.9-12 The facial nerve exits the cranium through the stylomastoid foramen, courses through the parotid gland, and divides into the temporozygomatic and cervicofacial divisions and then further into five main branches: temporal, zygomatic, buccal, mandibular, and cervical.13 Injury to the temporal branch can result in paralysis and cosmetic deformity of the frontalis, orbicularis oculi, and corrugator supercilii muscles. This case report demonstrates a rare transient, unilateral neurapraxia of the frontalis muscle after Mayfield pin fixation and reviews the landmarks for the identification of the temporal branch of the facial nerve.
A 78-year-old man with ankylosis presented with a fracture involving the C7-T1 segment (Figure 1) after a ground level fall. Initial symptoms included axial neck pain with C8 radiculopathy and intrinsic muscle weakness. Owing to the fracture and resultant neurologic symptoms, the patient was counseled on cervical thoracic fusion. He underwent a C5 to T2 posterior fusion on an elective basis. Before positioning the patient prone, Mayfield skull clamps were applied. The surgery lasted 122 minutes and was without any intraoperative complications. Postoperatively, it was noted that his right frontalis muscle was unable to contract (Figure 2). The patient's neurapraxia was painless and without signs of infection or injury to the underlying bone. A thorough neurologic examination did not demonstrate any other muscle paresis, including the other muscles innervated by the facial nerve. The pin site was noted to be posterior to the eyebrow (Figure 3). His postoperative course was otherwise uncomplicated. The patient was followed in the outpatient setting, and his frontalis palsy resolved spontaneously without any intervention by 2 months (Figure 4). He healed appropriately with regard to his cervical thoracic fusion (Figures 5 and 6) and had improvement in his clinical symptoms, including improvement in sensation and strength of his hand.
Skull clamp fixation is used to provide stabilization during surgical procedures with limited complications, which can generally be avoided with proper placement. Frontalis palsy has never been reported but underscores the importance of a detailed understanding of facial anatomy, including the at-risk temporal branch of the facial nerve due to its subcutaneous course, particularly at the lateral border of the frontalis muscle.9-12 Using the safe zone of placement illustrated by Beuriat et al7 will limit most complications. The safe zone avoids placement of the pin along the course of the facial nerve as it courses through the parotid gland. Pins should be placed along the center line of the calvarium, the region where a sweatband would be worn, with an equal distance between the pins will avoid slippage.
The plastic surgery literature has identified landmarks to estimate the course of the temporal branch of the facial nerve with consideration of anatomical variations, so that injury can be minimized during procedures. Pitanguy and Ramos9 described a line starting 0.5 cm inferior to the tragus, the external ear prominence anterior to the concha, connecting to 1.5 cm superior to the lateral eyebrow. Correia et al11 described its path along a course from two lines diverging starting at the inferior ear lobe and ending at the lateral eyebrow and to the highest frontal crease. These guidelines are dependent on using the eyebrow as a landmark, which can be variable in the cohort and potentially unreliable. Ishikawa10 estimated the course of the temporal branch using bony landmarks. A point 7 cm lateral to the lateral canthus on a line along the zygomatic arch and a point 4 cm superior to the lateral canthus on a line perpendicular to the first line; the temporal branch is estimated to course along a gently curved line connecting these two points.10 In our case, the skull clamp was likely placed too anterior and injured the nerve along its course to the frontalis muscle; fortunately, the neurapraxia resolved with time. This was a rare but important complication to recognize to decrease the morbidity and potential cosmetic deformity with the use of skull clamps. Using the projected safe zones described by Beuriat et al7 and the general course of the temporal nerve outlined by Ishikawa10 should avoid frontalis palsy.
Given the rarity of frontalis palsy, there are no clinical recommendations on the diagnostic and treatment course. Clinical practice guidelines for facial nerve weakness or paralysis, Bell's palsy, could serve as a guideline for diagnostic and treatment options.14 These guidelines strongly recommend for oral steroids and against electrodiagnostic testing for incomplete paralysis.14 In the event frontalis palsy does occur after placement of the Mayfield skull clamp, the patient can be monitored for improvement in the acute postoperative period with a short course of oral steroids if there are no clinical contraindications.
1. Lee MJ, Lin EL: The use of the three-pronged Mayfield head clamp resulting in an intracranial epidural hematoma in an adult patient. Eur Spine J 2010;19(suppl 2):S187-S189.
2. Gelabert-González M, Serramito-García R: Mayfield head clamp and intracranial epidural hematoma. Eur Spine J 2011;20:986.
3. Matouk CC, Ellis MJ, Kalia SK, et al.: Skull fracture secondary to application of a Mayfield skull clamp in an adult patient: Case report and review of the literature. Clin Neurol Neurosurg 2012;114:776-778.
4. Prabhakar H, Ali Z, Bhagat H: Venous air embolism arising after removal of Mayfield skull clamp. J Neurosurg Anesthesiol 2008;20:158-159.
5. De Lange JJ, Baerts WD, Booij LH: Air embolism due to the Mayfield skull clamp. Acta Anaesthesiol Belg 1984;35:237-241.
6. Moumoulidis I, Fernandes H: CSF rhinorrhea secondary to use of a Mayfield head clamp. Ear Nose Throat J 2008;87:E1-E3.
7. Beuriat PA, Jacquesson T, Jouanneau E, et al.: Headholders'—Complications in neurosurgery: A review of the literature and recommendations for its use. Neurochirurgie 2016;62:289-294.
8. Demiröz S, Ketenci IE, Yanik HS, Erdem S: A rare complication of spine surgery: Case report of peripheral facial palsy. J Neurosurg Anesthesiol 2017;29:468-469.
9. Pitanguy I, Ramos AS: The frontal branch of the facial nerve: The importance of its variations in face lifting. Plast Reconstr Surg 1966;38:352-356.
10. Ishikawa Y: An anatomical study on the distribution of the temporal branch of the facial nerve. J Craniomaxillofac Surg 1990;18:287-292.
11. Correia PC, Zani R: Surgical anatomy of the facial nerve, as related to ancillary operations in rhytidoplasty. Plast Reconstr Surg 1973;52:549-552.
12. Ammirati M, Spallone A, Ma J, et al.: An anatomicosurgical study of the temporal branch of the facial nerve. Neurosurgery 1993;33:1038-1043.
13. Schleicher W, Feldman M, Rhodes J: Review of facial nerve anatomy: Trauma to the temporal region. Eplasty 2013;13:ic54.
14. Baugh RF, Basura GJ, Ishii LE, et al.: Clinical practice guideline: Bell's palsy. Otolaryngol Head Neck Surg 2013;149:S1-S27.