Nerve Block Guided by Anatomic Landmarks Only Reduces Pain in Botulinum Toxin Type A Treatment for Glabellar and Forehead Wrinkles.

BACKGROUND: Botulinum toxin type A is widely used to treat glabellar and forehead wrinkles, but the pain caused by multiple injections often deters patients from receiving long-term treatment. Despite several methods used to alleviate this pain, consistency and effectiveness remain a challenge. Therefore, this study aimed to evaluate the effectiveness and safety of nerve block guided by anatomic landmarks only in reducing pain associated with botulinum toxin type A injections. PATIENTS AND METHODS: Between 2018 and 2022, the study enrolled 90 patients divided into 3 groups: the nerve block group (n = 30), the lidocaine cream group (n = 30), and the control group (n = 30). In the nerve block group, a landmarks-based technique was used to perform the nerve block. The study collected general information and comorbidities, and recorded pain at each point and time spent on preparation and treatment for each patient's forehead and glabellar area on each side. Patient-reported outcomes and complications were followed up at 2, 4, and 12 weeks after the injections. RESULTS: The nerve block group had significantly lower total pain scores in all regions compared to the lidocaine cream and control groups (P < 0.01). There were no significant differences in patient-reported outcomes between the groups at any follow-up point. Additionally, the complication rates related to injection were low and comparable among the 3 groups. CONCLUSIONS: Nerve block guided by anatomic landmarks only is a safe, effective, and consistent approach to reduce pain during botulinum toxin type A treatment for glabellar and forehead lines. This technique may offer advantages over other methods used to alleviate the pain associated with these injections.

Anatomic Variations of the Lateral Branch of the Supraorbital Nerve Observed in Endoscopic Forehead Surgery.

Surgeons dissect carefully in the medial third of the supraorbital rim to preserve the supraorbital nerve (SON) during surgical forehead rejuvenation. However, the anatomic variations of SON exit from the frontal bone have been researched in cadaver or imaging studies. In this study, we report a variation in the lateral branch of SON observed in an endoscopic view during forehead lifts. A retrospective review of 462 patients who underwent endoscopy-assisted forehead lifts between January 2013 and April 2020 was performed. Data, including the location, number, and form of the exit point and thickness of SON and its lateral branch variant, were recorded and reviewed intraoperatively, utilizing high-definition endoscopic assistance. Thirty-nine patients and 51 sides were included, and all patients were female, with a mean age of 44.53 (18-75) years. This nerve exited a foramen in the frontal bone ~8.82 ± 2.79 mm lateral to SON and ~1.89 ± 1.34 mm from the supraorbital margin vertically. Observed thickness variations of the lateral branch of SON included 20 small, 25 medium, and 6 large nerves. This study revealed various positional and morphologic variations of the lateral branch of SON in an endoscopic view. Thus, surgeons can be alerted of the anatomic variations of SON and establish careful dissection during procedures. In addition, the findings of this study will be useful in planning nerve blocks, filler injections, and migraine treatments in the supraorbital region.

Forehead Movement Discrepancies After Botulinum Toxin Injections: A Review of Etiology, Correction, and Prevention.

BACKGROUND: Forehead rhytides are a popular target for botulinum toxin injections, but neuromodulation of the frontalis can be fraught with complications because of its anatomic complexity and integral role in brow position and expressivity. OBJECTIVE: This article explores common forehead movement discrepancies that can occur after neuromodulation of the frontalis, as well as how to correct and prevent them. METHODS: A review of the literature was conducted and combined with clinical experience to examine underlying forehead anatomy, etiology and correction of forehead movement discrepancies, and important factors to consider before injecting the frontalis with botulinum toxin. RESULTS AND CONCLUSION: Variable anatomy from person to person necessitates an individualized treatment approach to achieve the best cosmetic results and prevent the occurrence of forehead movement discrepancies.

Computed Tomography-Guided Radiofrequency Ablation of the Cervical Dorsal Root Ganglia in 27 Patients with Cervical and Occipital Postherpetic Neuralgia.

BACKGROUND Postherpetic neuralgia (PHN) is a common complication of herpes zoster virus infection that is associated with intense pain. The present study aimed to investigate the use of computed tomography (CT)-guided radiofrequency ablation (RFA) of the cervical dorsal root ganglia (DRG) for treatment of cervical and occipital PHN in 27 patients at a single center. MATERIAL AND METHODS Twenty-seven patients with PHN in the cervical and/or occipital region were enrolled. After imaging the area of PHN in the patients, axial scanning was performed on the upper cervical segment in the spinal scanning mode. The puncture path was defined and then RFA therapy (90°C for 180 s) was performed by targeting the corresponding intervertebral foramen. Patients were followed 2 days later and at 1, 3, 6, and 12 months after surgery. Observation at each follow-up visit included rating of pain on a visual analog scale (VAS) and assessment of complications and adverse events. RESULTS VAS scores significantly decreased in patients with PHN after RFA compared with their scores before RFA (P<0.05). Skin sensation decreased in the area that was originally painful and allodynia significantly diminished. CONCLUSIONS The findings from this small study from a single center showed that CT-guided percutaneous RFA of cervical DRG safely and effectively reduced cervical and occipital PHN in the short term.

Aesthetic ONE21 Technique for Injecting IncobotulinumtoxinA into the Forehead: Initial Experience With 86 Patients.

BACKGROUND: Treatment of upper facial lines is a common aesthetic practice; however, there is limited information on systematic tailored approaches for the treatment of forehead wrinkles using botulinum toxin A. OBJECTIVE: To describe the safety and efficacy of the ONE21 technique using incobotulinumtoxinA (INCO) for the treatment of forehead wrinkles. METHODS: Single-center, retrospective study with 86 females presenting a baseline Merz Aesthetic Scale (MAS) score ≥2 for dynamic forehead lines who had been treated with INCO using the ONE21 technique. Assessment was performed by two independent blinded raters using MAS for forehead lines (dynamic and at rest), and eyebrow positioning, based on standardized pictures taken before (baseline) and 4 (±2) weeks after treatment injection. The primary outcome was the percentage of subjects with a MAS improvement ≥2 points for dynamic forehead lines at week 4 (±2). Secondary outcomes were MAS scores for resting forehead lines and for eyebrow positioning. RESULTS: The mean age was 46.2 years, and mean total dose of INCO, 20.3 U. Most (97.7%) subjects had a MAS improvement of ≥2 points for dynamic forehead lines at week 4 (±2); 100% improved ≥1 point. MAS scores for resting and dynamic lines, and eyebrow positioning were significantly improved (P<0.001). Eyebrow positioning MAS improved ≥1 point in 56.9% of subjects, and 39.5% maintained the original shape. CONCLUSION: INCO injection using the ONE21 technique is effective and safe in treating forehead wrinkles, providing a natural result, with a customized treatment and a predictable eyebrow shape. J Drugs Dermatol. 2021;20(1):31-37. doi:10.36849/JDD.5617.

Migraine Surgery at the Frontal Trigger Site: An Analysis of Intraoperative Anatomy.

BACKGROUND: The development of migraine headaches may involve the entrapment of peripheral craniofacial nerves at specific sites. Cadaveric studies in the general population have confirmed potential compression points of the supraorbital and supratrochlear nerves at the frontal trigger site. The authors' aim was to describe the intraoperative anatomy of the supraorbital and supratrochlear nerves at the level of the supraorbital bony rim in patients undergoing frontal migraine surgery and to investigate associated pain. METHODS: PATIENTS: scheduled for frontal-site surgery were enrolled prospectively. The senior author (W.G.A.) evaluated intraoperative anatomy and recorded variables using a detailed form and operative report. The resulting data were analyzed. RESULTS: One hundred eighteen sites among 61 patients were included. The supraorbital nerve traversed a notch in 49 percent, a foramen in 41 percent, a notch plus a foramen in 9.3 percent, and neither a notch nor a foramen in one site. The senior author noted macroscopic nerve compression at 74 percent of sites. Reasons included a tight foramen in 24 percent, a notch with a tight band in 34 percent, and supraorbital and supratrochlear nerves emerging by means of the same notch in 7.6 percent or by means of the same foramen in 4.2 percent. Preoperative pain at a site was significantly associated with nerve compression by a foramen. CONCLUSIONS: The intraoperative anatomy and cause of nerve compression at the frontal trigger site vary greatly among patients. The authors report a supraorbital nerve foramen prevalence of 50.3 percent, which is greater than in previous cadaver studies of the general population. Lastly, the presence of pain at a specific site is associated with macroscopic nerve compression.

Differential innervation of tissues located at traditional acupuncture points in the rat forehead and face.

OBJECTIVES: To compare the neural pathways associated with the tissues located at different traditional acupuncture points in the rat forehead and face using the cholera toxin B subunit (CTB) neural tracing technique. METHODS: After injection of CTB into the tissues at GB14, ST2 and ST6 in the rat, the neural labelling associated with each acupuncture point was revealed by fluorescent immunohistochemistry of the nervous system, including the trigeminal ganglion (TRG), cervical dorsal root ganglia (DRG), spinal cord and brain. RESULTS: The CTB labelling included sensory neurons and their transganglionic axonal terminals, as well as motor neurons. The labelled sensory neurons associated with GB14, ST2 and ST6 were distributed in both the TRG and cervical DRG, and their centrally projected axons terminated in an orderly fashion at their corresponding targets in the spinal trigeminal nucleus and cervical spinal dorsal horn. In addition, labelled motor neurons were observed in the facial motor nucleus, trigeminal motor nucleus and cervical spinal ventral horn, in which facial motor neurons projected to the tissues located at all three acupuncture points. Trigeminal motor neurons innervated both ST2 and ST6, while spinal motor neurons only correlated with ST6. CONCLUSIONS: These results indicate that the tissues located at each of these three traditional acupuncture points in the rat forehead and face has its own sensory and motor connection with the nervous system in a region-specific pattern through distinct neural pathways. Understanding the neuroanatomical characteristics of acupuncture points from the peripheral nervous system to the central nervous system should help inform acupuncture point selection according to the demands of the clinical situation.

Treatment of Frontal Secondary Headache Attributed to Supratrochlear and Supraorbital Nerve Entrapment With Oral Medication or Botulinum Toxin Type A vs Endoscopic Decompression Surgery.

IMPORTANCE: Endoscopic surgical decompression of the supratrochlear nerve (STN) and supraorbital nerve (SON) is a new treatment for patients with frontal chronic headache who are refractory to standard treatment options. OBJECTIVE: To evaluate and compare treatment outcomes of oral medication, botulinum toxin type A (BoNT/A) injections, and endoscopic decompression surgery in frontal secondary headache attributed to STN and supraorbital SON entrapment. DESIGN, SETTING, AND PARTICIPANTS: Prospective cohort study of 22 patients from a single institution (Diakonessen Hospital Utrecht) with frontal headache of moderate-to-severe intensity (visual analog scale [VAS] score, 7-10), frontally located, experienced more than 15 days per month, and described as pressure or tension that intensifies with pressure on the area of STN and SON. A screening algorithm was used that included examination, questionnaire, computed tomography of the sinus, injections of local anesthetic, and BoNT/A in the corrugator muscle. INTERVENTIONS: Different oral medication therapy for headache encountered in the study cohort, as well as BoNT/A injections (15 IU) into the corrugator muscle. Surgical procedures were performed by a single surgeon using an endoscopic surgical approach to release the supraorbital ridge periosteum and to bluntly dissect the glabellar muscle group. MAIN OUTCOMES AND MEASURES: Headache VAS intensity after oral medication and BoNT/A injections. Additionally, early postoperative follow-up consisted of a daily headache questionnaire that was evaluated after 1 year. RESULTS: In total, 22 patients (mean [SD] age, 42.0 [15.3] years; 7 men and 15 women) were included in this cohort study. Oral medication therapy reduced the headache intensity significantly (mean [standard error of the mean {SEM}] VAS score, 6.45 [0.20] [95% CI, 0.34-3.02; P < .001] compared with mean [SEM] pretreatment VAS score, 8.13 [0.22]). Botulinum toxin type A decreased the mean (SEM) headache intensity VAS scores significantly as well (pretreatment, 8.1 [0.22] vs posttreatment, 2.9 [0.42]; 95% CI, 3.89-6.56; P < .001). The mean (SEM) pretreatment headache intensity VAS score (8.10 [0.22]) decreased significantly after surgery at 3 months (1.30 [0.55]; 95% CI, 5.48-8.16; P < .001) and 12 months (1.09 [0.50]; 95% CI, 5.71-8.38; P < .001). There was a significant decrease of headache intensity VAS score in the surgical group over the BoNT/A group (mean [SEM] VAS score, 2.90 [0.42]) after 3 months (mean [SEM] VAS score, 1.30 [0.55]; 95% CI, 0.25-2.93; P < .001) and 12 months (mean [SEM] VAS score, 1.09 [0.50]; 95% CI, 0.48-3.16; P < .001) after surgery. CONCLUSIONS AND RELEVANCE: Endoscopic decompression surgery had a long-lasting successful outcome in this type of frontal secondary headache. Even though BoNT/A had a positive effect, the effect of surgery was significantly higher. LEVEL OF EVIDENCE: 3.

Painful stimulation of a sensitized site in the forearm inhibits ipsilateral trigeminal nociceptive blink reflexes.

Exposure to moderate levels of ultraviolet B radiation (UVB) is painless but nevertheless induces an inflammatory response that sensitizes primary afferent nociceptors. Subsequently, heating the UVB-treated site can sensitize spinal nociceptors. We used a repeated-measures design to determine whether heating the UVB-treated site also triggers ipsilateral inhibitory controls. Specifically, a 2-cm diameter site on the forearm of 20 participants was exposed to UVB at twice the minimum erythema dose. 48 h later mechanical and thermal sensitivity had increased at the UVB-treated site, indicating primary hyperalgesia. In addition, sensitivity to blunt pressure had increased in the ipsilateral forehead, implying activation of an ipsilateral supra-spinal pro-nociceptive mechanism. Despite this, the area under the curve of the ipsilateral nociceptive blink reflex decreased when the UVB-treated site was heated to induce moderate pain. Together, these findings suggest that the UVB treatment sensitized primary nociceptive afferents and generated an ipsilateral supra-spinal pro-nociceptive mechanism. In addition, sensitization to heat induced by the UVB treatment strengthened an ipsilateral anti-nociceptive process elicited by heat-pain. Infrequent but enduring discharge of sensitized primary nociceptive afferents, driven by inflammation after UVB exposure, might initiate a lateralized supra-spinal pro-nociceptive influence that heightens awareness of impending harm on the sensitized side of the body. In addition, a lateralized anti-nociceptive response triggered by an intense barrage of nociceptive signals may help to differentiate stronger from weaker sources of pain.

Accessory Nerves of the Forehead: A Newly Discovered Frontotemporal Neurovascular Bundle and Its Implications in the Treatment of Frontal Headache, Migraine Surgery, and Cosmetic Temple Filler Injection.

BACKGROUND: Surgical decompression of peripheral cranial and spinal nerves at several anatomically studied trigger sites has demonstrated significant efficacy in bringing permanent relief to migraine sufferers. In their experience performing frontal nerve decompression on migraine patients, the authors noticed a previously undescribed accessory nerve and vessel in the frontotemporal area, and report its implication in migraine surgery and cosmetic filler injection. METHODS: A retrospective review of 113 patients who underwent frontal migraine decompression surgery with the senior author at the University of Texas Southwestern Medical Center from July of 2012 to May of 2016 was performed. For the included 76 patients, measurements of this nerve had been taken intraoperatively using high-definition endoscopic assistance, and topographic measurements were correlated with endoscopic location of the nerve. RESULTS: This frontotemporal nerve (FTN) was present in 55 percent, and the bilateral incidence was 57 percent of those. An accompanying vessel was also present in 81 percent of nerve complexes. Both nerve and vessel varied in size. A large vessel was present in 8 percent of all patients, and a medium vessel was present in 20 percent. Consistently, the nerve exited a foramen in the frontal bone on average 3.4 ± 0.47 cm superior to the lateral canthus. CONCLUSIONS: The identification and proper avulsion neurectomy of this newly described sensory FTN may lead to better surgical response rate during migraine surgery. In addition, this nerve should be considered during nerve block and botulinum toxin injections in migraine treatment. The existence of the accompanying vessel could have significant implications in the safety of filler and fat injections to this area.

Morphometric Evaluation of the Frontal Migraine Trigger Site.

BACKGROUND: Migraine headache has been attributed to specific craniofacial peripheral nerve trigger sites. Some have postulated that hypertrophy of the corrugator muscles causes compression of the supraorbital and supratrochlear nerves, resulting in migraine headache. This study uses morphometric evaluation to determine whether corrugator anatomy differs between patients with migraine headache and control subjects. METHODS: A retrospective review identified patients with and without migraine headache who had a recent computed tomographic scan. Morphometric evaluation of the corrugator supercilii muscles was performed in a randomized and blinded fashion on 63 migraine headache and 63 gender-matched control patients using a three-dimensional image-processing program. These images were analyzed to determine whether corrugator size differed between migraine and control patients. RESULTS: There was no difference in mean corrugator volume or thickness between migraine and control patients. The mean corrugator volume was 1.01 ± 0.26 cm compared with 1.06 ± 0.27 cm in control patients (p = 0.258), and the mean maximum thickness was 5.36 ± 0.86 mm in migraine patients compared with 5.50 ± 0.91 mm in controls (p = 0.359). Similarly, subgroup analysis of 38 patients with frontal migraine and 38 control subjects demonstrated no difference in corrugator size. Further subgroup analysis of nine patients with unilateral frontal migraine showed no difference in corrugator size between the symptomatic side compared with the contralateral side. CONCLUSIONS: Muscle hypertrophy itself does not play a major role in triggering migraine headache. Instead, factors such as muscle hyperactivity or peripheral nerve sensitization may be more causative.

Painful Neuroma Treatment of the Supraorbital Nerve and Forehead Neurotization Using Human Cadaveric Nerve Allograft.

Neuroma pain can be severe, persistent, and treatment-resistant. Forehead and scalp anesthesia is troublesome for patients. Following an iatrogenic ablative injury to the right supraorbital nerve, with subsequent painful neuroma formation, a human cadaveric nerve allograft (AxoGen, Alachua, FL) was used to restore sensation of the right forehead and treat pain. At 1-year follow-up, the patient was pain-free, and protective sensation to the right forehead was recovered with comparable static and dynamic 2-point discrimination between the injured (20 mm, 12 mm respectively) and the normal side (15 mm, 10 mm respectively). This is the first reported case of using a cadaver nerve allograft for successful direct neurotization of the skin and restoration of sensation in the upper part of the face, and for treating painful neuromas. Moreover, a brief review of the available techniques for treating neuromas of the supraorbital and supratrochlear nerves is provided.

Superficial temporal artery perforator flap: Anatomic study of number and reliability of distal branches of the superficial temporal artery and clinical applications in three cases.

BACKGROUND: Limited information is available about the anatomical feasibility and clinical applications of flaps based on distal divisions of the superficial temporal artery (STA). The aim of this study was to investigate the anatomy of the STA, focusing on the number and reliability of distal branches and to show representative cases for the use of such flaps for zygomatic, parieto-frontal and occipital reconstructions. METHODS: Fifty volunteers were examined bilaterally by Doppler to investigate the presence and variability of the distal divisions of STA branches. Dissection was performed on 14 temporal regions of 7 fresh cadavers. Three cases of reconstruction following skin cancer in the zygomatic (7 × 5 cm defect), parieto-frontal (4 × 4 cm defect) and occipital areas (4 × 2 cm defect) are presented. All the flaps were pedicled and based on a single vessel. RESULTS: In all the 50 volunteers, the parietal branch split into 2 ± 0 branches (anterior and posterior), bilaterally, while an average of 2.84 ± 0.46 and 2.82 ± 0.48 branches originated from the frontal vessel on the right and left side, respectively. 2 ± 0 parietal and 3 ± 0 frontal (superior, central, and inferior) cutaneous perforator branches were identified in all cadaveric specimens. Flaps (4 × 10 cm, 5 × 7 cm, and 2 × 5 cm, respectively, width × length) healed uneventfully providing stable coverage. CONCLUSIONS: STA distal perforator branches proved to be anatomically constant in both the cadaveric and clinical settings. Although a larger series of cases is needed, island flaps based on such vessels may represent a versatile surgical option, allowing a wide range of reconstructions in the different facial subunits.

Three-Dimensional Topography of the Supratrochlear Nerve With Reference to the Lacrimal Caruncle, and Its Danger Zone in Asians.

BACKGROUND: The supratrochlear nerve (STN) is relatively superficial and therefore vulnerable to iatrogenic injury. OBJECTIVE: To elucidate the course of STN with reference to the lacrimal caruncle, with the aim of preventing nerve injury during surgery in the forehead region. MATERIALS AND METHODS: Thirty-four hemifaces from 18 Korean cadavers were dissected. The vertical line through the apex of lacrimal caruncle and the horizontal line through the supraorbital margin were used as horizontal and vertical reference lines, respectively. The course of STN in the frontal view and the point at which it pierced the overlaying musculature were examined. RESULTS: After exiting the corrugator muscle cushion, the STN enters the subcutaneous plane by piercing the frontalis muscle. These piercing points occurred at mean horizontal and vertical distances relative to the medial branch of the STN of 9.2 and 9.6 mm, respectively; the corresponding distances for the lateral branch of the STN were 1.1 and 15.3 mm, respectively. CONCLUSION: When performing surgery in the medial forehead region, the surgeon must ensure that the dissection plane of forehead tissue is more superficial: superiorly within 1.5 cm from the supraorbital margin and medially within 1.0 cm from the vertical line through the apex of lacrimal caruncle.

Training of support afferentation in postmenopausal women.

We have recently shown a diminishing of the Menopause Index in old-aged women who underwent special training directed at the enhancement of support afferentation by increasing the plantar forefoot sensitivity (Bazanova et al., 2015). Based on these results we hypothesized, that purposeful training of support afferentation through stimulation of plantar graviceptors by Aikido practice will decrease excessive postural and psychoemotional tension not only in rest condition, but during cognitive and manual task performance too. Fluency of cognitive and motor task performance, EEG alpha power as an index of neuronal efficiency of cognitive control, amount of alpha power suppression as a visual activation measure and EMG power of forehead muscles as a sign of psychoemotional tension were compared in three groups of post-menopausal women: i) 8years training with forefeet support afferentation with Aikido practice (A), ii) 8years fitness training (F) and iii) no dedicated fitness training for past 8years (N). Simultaneous stabilometry, EEG, and frontal EMG recording were performed in sitting and standing up position in eyes closed and eyes open condition. Recording done at rest and while performing cognitive and finger motor tasks. We compared studied parameters between groups with one- and two-way analyses of variance (ANOVAs) with Bonferroni correction for multiple comparisons, followed by post hoc two-tailed unpaired t-tests. The fluency of tasks performance, EMG and alpha-EEG-activity displayed similar values in all groups in a sitting position. Center of pressure (CoP) sway length, velocity and energy demands for saving balance increased when standing up, more in group N than in groups F and A (all contrasts p values<0.002, η2>0.89). Post hoc t-tests showed increased fluency in standing in both Aikido (p<0.01) and Fitness (p<0.05) subjects in relation to untrained subjects. Increasing fluency in motor task performance was in parallel with enhancing the EEG alpha-2-power and decreasing EMG power only in A group (η2>0.77). Fluency in motor task and alpha EEG power decreased, but frontal EMG power increased in response to standing in untrained women (group N) and did not change in F group. Post hoc t-tests showed that EEG amount of alpha-2 power suppression in response to visual activation and frontal EMG power was lower in A than F and N groups (p<0.004) during motor task performance in the standing position. These results were interpreted as showing that training of forefoot plantar surface sensitivity in postmenopausal women decreases levels of psychoemotional tension and increases cognitive control caused by the psychomotor and postural challenges. Thus, Aikido training aimed at learning coordination between manual task performance and balance control by increasing the plantar support zones sensation decreases the cost of maintained vertical position and dependence of motor coordination on visual contribution.

Topography of the supraorbital nerve with reference to the lacrimal caruncle: danger zone for direct browplasty.

PURPOSE: To elucidate the course of the supraorbital nerve (SON) with reference to the lacrimal caruncle in order to facilitate safer direct browplasty by preventing nerve injury. METHODS: Thirty-four hemifaces from 18 embalmed Korean cadavers were dissected. A vertical line through the upmost point of the lacrimal caruncle and a horizontal line through the supraorbital margin were used as the horizontal and vertical reference positions, respectively. The course of the SON in the frontal view and the point at which it pierced the overlaying musculature were examined. RESULTS: The SON divides into a superficial branch and a deep branch just after exiting the orbit. In all cases, the deep SON remains in the subgaleal plane deep to the corrugator and frontalis muscles. The superficial SON travels under the corrugator muscle dividing into three branches (medial, intermediate and lateral) and pierced the frontalis muscle at 19-32 mm above the supraorbital margin. However, in 11 cases (32%) the medial branch of the superficial SON pierced the lower portion of the corrugator muscle at 3.6 mm above the supraorbital margin and ran in front of the muscle along with the vertical line through the upmost point of the lacrimal caruncle. CONCLUSIONS: One-third of the medial branch of the superficial SON without corrugator muscle protection is vulnerable to iatrogenic injury during direct browplasty. Therefore, the oculofacial surgeon must bring the dissection plane of the forehead tissue more superficially around the vertical line through the upmost point of the lacrimal caruncle in order to avoid nerve injury.