Treatment Outcome of Conjunctival Cyst Ablation by Pattern Scan Laser.

PURPOSE: To evaluate the effectiveness of conjunctival cyst ablation using pattern scan laser photoablation. METHODS: Ninety-four cases of symptomatic conjunctival cysts were included. After staining the surface of a conjunctival cyst with a dark-purple marker pen, an incision was made into the conjunctival cyst using a 26-gauge needle. Low-energy photoablation using 3 × 3 grids of spots was then applied around the incision site for a mean of 50 times. The laser spots were 400 µm in size, the power delivered ranged from 400 to 450 mW, and the duration of each laser pulse was 80 ms. RESULTS: During a mean follow-up period of 6.5 months (range 6-16 months), 84 cases of conjunctival cysts (89.4%) were successfully corrected by conducting either 1 or 2 laser sessions. The cyst was completely resolved after a single laser session in 74 cases (78.7%). There were 20 cases of recurrence, which involved fixed, thick, and large cysts. The conjunctival cyst recurred again after the second laser session in 2 of the 12 eyes in which the procedure was repeated. The remaining 8 cases were observed without additional treatment. No postoperative complications such as conjunctival scarring or persistent ocular irritation were observed. CONCLUSIONS: Pattern scan laser photoablation of a conjunctival cyst with the adjunctive use of cyst surface staining to increase the amount of thermal laser energy absorption is a simple and effective method for treating conjunctival cysts in an outpatient clinic.

Anatomical Relationship between the Inferior Temporal Septum and the Temporal Branch of the Facial Nerve for Clinical Applications.

BACKGROUND: The inferior temporal septum (ITS) is a fibrous adhesion between the superficial temporal fascia and the superficial layer of the deep temporal fascia. This study identified detailed the anatomical relationship between the ITS and the temporal branch of the facial nerve (TBFN) for facial nerve preservation during temple interventions. METHODS: Among 33 Korean cadavers, 43 sides of TBFNs in temporal regions were dissected after identifying the ITS between the superficial temporal fascia and superficial layer of the deep temporal fascia through blunt dissection. The topography of the ITS and TBFN were investigated with reference to several facial landmarks. Regional relationships with the ITS and TBFN within the temporal fascial layers were histologically defined from five specimens. RESULTS: At the level of the inferior orbital margin by the tragion, the mean distances from the lateral canthus to the anterior and posterior branches of the TBFN were 5 and 6.2 cm, respectively. At the lateral canthus level, the mean distance from the lateral canthus to the posterior branch of the TBFN was similar to that to the ITS, at 5.5 cm. At the superior orbital margin level, the posterior branch of the TBFN ran cranial to the ITS adjacent to the frontotemporal region. The TBFN ran through the subsuperficial temporal fascia layer and the nerve fibers located cranially, and within the ITS meshwork in the upper temporal compartment. CONCLUSION: The area of caution during superficial temporal fascia interventions related to the TBFN was clearly identified in the upper temporal compartment, which is known to lack important structures.

An Unexpected Complication Resulting from Radiofrequency Ablation for Treating Facet Joint Syndrome: A Case Report.

Lumbar facet joints have been identified as a potential source of chronic low back pain (LBP) in 15% to 45% of patients, with the prevalence of such pain varying based on specific populations and settings examined. Lumbar facet joint interventions are useful in the diagnosis as well as the therapeutic management of chronic LBP. Radiofrequency ablation (RFA) of medial branch nerves is recognized as a safe and effective therapy for chronic facet joint pain in the lumbosacral spine, and its efficacy has already been established. The use of RFA is currently widespread in the management of spinal pain, but it is noteworthy that there have been works in the literature reporting complications, albeit at a very low frequency. We present a case of third-degree skin burns following radiofrequency ablation (RFA) for the management of facet joint syndrome. Postoperatively, the patient's skin encircling the needle displayed a pallor and exhibited deterioration in conjunction with the anatomical anomaly. The affected area required approximately 5 months to heal completely. During RFA, heat can induce burns not only at the point of contact with the RF electrode but also along the length of the needle. Vigilant attention is necessary to ensure patient safety and to address any potential complications that may arise during the procedure, including the possibility of minor technical errors.

Modified argon laser therapy for benign tumor of the eyelid.

BACKGROUND: To report about the therapy of benign eyelid tumors with a modified argon laser technique as an alternative to surgery. METHODS: Nineteen benign tumors of the eyelid were included in this study. After staining the surface of the tumor with a violet marker, low-energy argon laser photoablation was performed. A mean number of 312 spots (spot size ranging from 150 to 500 µm) with a power of 200 to 400 mW, and a duration between 0.1 and 0.2 s were applied. RESULTS: The eyelid tumors were located mainly in the lower eyelid (58%). Dermal nevi and papilloma were the most frequently treated lesions. Over a mean follow-up period of 10.5 months (range 6-18 months), all eyelid tumors were successfully treated by a single session of laser therapy. All patients were satisfied with the laser therapy and the cosmetic result. No postoperative complications were observed. No relapses occurred during follow-up. CONCLUSIONS: Our modified method of argon laser therapy utilizes the staining of the surface of the eyelid tumor to increase the amount of thermal laser energy absorbed by the target. This novel technique is simple and effective for treating benign eyelid tumors.

Morphological changes after lower eyelid epiblepharon surgery in Asian children.

BACKGROUND: This study aimed to determine the morphological changes in Asian lower eyelid epiblepharon patients after surgery. METHODS: The medical records of 59 patients who underwent lower eyelid epiblepharon repair were reviewed retrospectively. Eighty-nine patients who underwent strabismus surgery were set as the control group. The photographs for each group were analyzed based on the following factors: inferior half area (IHA) of the eye, eyelash angular direction (EAD), angle between the eyelashes and the cornea, marginal reflex distance 1 (MRD1) and marginal reflex distance 2 (MRD2). RESULTS: After surgery, the medial EAD changed from 92.45° ± 20.21° (mean ± SD) to 79.43° ± 23.31°, while the central and lateral EADs were unchanged. IHA increased from 36.33 ± 9.78 mm3 to 43.06 ± 10.57 mm3, and MRD1 increased from 1.92 ± 0.99 mm to 2.50 ± 0.93 mm, whereas MRD2 did not change. The mean angle between the eyelashes and the cornea increased from 39.64° to 72.19° immediately postoperatively, but had reduced to 58.75° 3 months later, followed by no further significant change at the 6-month and 9-month postoperative follow-ups. CONCLUSIONS: There is morphological changes of the eyelid after lower eyelid epiblepharon surgery, with increases in the IHA and MRD1. In addition, contact between the eyelashes and the cornea occurred mainly in the medial portion of the eyelid the position, which everted and stabilized over 3 months. Thus, follow-up observations are required for at least 3 months to properly evaluate the surgical outcome.

Investigation of the Orbital Arterial Distribution Using Image Superimposition to Determine Safe Zones for Retrobulbar Injection and to Prevent Filler Complications.

BACKGROUND: Retrobulbar filler injection has recently been considered an ideal method for orbital volume enhancement due to its nontoxic, easily reversible, and noninvasive characteristics. This study determined the arterial distribution in the orbit with the aim of defining a safety zone for retrobulbar filler injections used to enhance the orbital volume. METHODS: Twenty-seven orbits of 24 formalin-embalmed cadavers were dissected. The orbital arteries were identified after removal of the eyeball, extraocular muscles, and connective tissues. The course of each orbital artery was then recorded in each specimen, and all of the courses were then superimposed to determine the arterial distribution in the orbit. RESULTS: The superimposition of lined images based on the orbital vasculature of each specimen revealed that the arterial density was highest in the superonasal region and lowest in the inferotemporal region. In particular, orbital arteries were scarce at 8 o'clock and 4 o'clock in the right and left orbits, respectively, and an artery-free zone was demonstrated in the outer part of those directions. CONCLUSIONS: When performing a transcutaneous retrobulbar injection of filler for orbital volume enhancement, the relative safety zone could be considered to be located at 8 o'clock and 4 o'clock in the right and left orbits, respectively. The detailed topographic information about the arterial distribution in the orbit, provided by the present study, may help oculofacial surgeons to avoid injury to major vessels and decrease the risk of retrobulbar hemorrhage and vision-threatening complications.

Anatomic, histologic, and ultrasound analyses of the dorsum of the hand for volumetric rejuvenation.

BACKGROUND: Volumetric rejuvenation of the dorsum of the hand with fat grafting or injectable fillers has increased in popularity in recent years. It has become widely accepted that the dorsum of the hand contains three fatty laminae: superficial, intermediate, and deep laminae. The dorsal venous plexus and dorsal cutaneous nerves are known to reside in the dorsal intermediate lamina. However, the superficial vein and cutaneous nerve might not be located in the same layer of subcutaneous tissue, as is the case in other body regions. MATERIALS AND METHODS: Eight hands were dissected in a layer-by-layer fashion from the skin to the extensor tendons. In another 13 hands from among 21 investigated cadavers, samples from the dorsum of the hand were harvested and stained using trichrome stains for histologic analysis. B-mode ultrasound was also performed for identifying structures of the dorsum of the hand. RESULTS: Anatomic dissection and histologic analysis of the dorsum of the hand revealed the presence of an unknown fascia in addition to the three known fascial layers. The additional fascia was located in the dorsal intermediate lamina and separated it into two compartments: one containing the dorsal venous plexus superficially and the other containing the dorsal cutaneous nerves deeply. Ultrasound showed corresponding structures including three hyperechoic fascial layers, three hypoechoic laminae, and additional hyperechoic fascia in dorsal intermediate lamina. CONCLUSIONS: Accurate anatomic knowledge of the dorsum of the hand will help practitioners determine the optimal and safe locations for performing fat grafting and injecting dermal fillers.

New instrument for quantitative measurements of passive duction forces and its clinical implications.

PURPOSE: Evaluating the passive duction force of the extraocular muscles is important for the diagnosis of and surgical planning for strabismus. This is especially relevant in patients with an observable limitation of duction movement. The purpose of this study was to validate passive duction forces in healthy subjects using a novel instrument. METHODS: An instrument for making continuous quantitative measurements of passive duction forces was designed. Tension was measured as the eyeball was rotated horizontally or vertically from the resting position under general anesthesia 10 mm (50°) away from the direction of force to be tested (opposite side). RESULTS: Seventy eyes of 35 subjects were enrolled in this study (age range of 4-80 years and mean age of 36.3 years). The passive duction force was measured at 49.0 ± 15.3 g (mean ± standard deviation) for medial rotation, 44.8 ± 13.2 g for lateral rotation, 50.5 ± 14.8 g for superior rotation, and 53.5 ± 13.8 g for inferior rotation. The passive duction forces were similar for all gaze positions, but it was larger for inferior rotation than for lateral rotation (P = 0.009). The passive duction force was significantly larger for vertical rotation (51.9 ± 14.4 g) than for horizontal rotation (46.9 ± 14.4 g) (P = 0.006). The passive duction force did not differ significantly with sex (P = 0.355), side (P = 0.087), or age (P = 0.872). CONCLUSIONS: These measurements of passive duction forces in a healthy population provide valuable information for diagnosing specific strabismic problems and could be useful for increasing the precision of strabismus surgery. Graphical abstract.

Intramuscular Nerves of the Inferior Rectus Muscle: Distribution and Characteristics.

PURPOSE: Knowledge of the distribution of intramuscular nerves of the extraocular muscles is crucial for understanding their function. The purpose of this study was to elucidate the intramuscular distribution of the oculomotor nerve within the inferior rectus muscle (IRM) using Sihler's staining. METHOD: Ninety-three IRM from 50 formalin-embalmed cadavers were investigated. The IRM including its branches of the oculomotor nerve was finely dissected from its origin to the point where it inserted into the sclera. The intramuscular nerve course was investigated after performing Sihler's whole-mount nerve staining technique that stains the nerves while rendering other soft tissues either translucent or transparent. RESULTS: The oculomotor nerve enters the IRM around the distal one-fourth of the muscle and then divides into multiple smaller branches. The intramuscular nerve course finishes around the distal three-fifth of the IRM in gross observations. The types of branching patterns of the IRM could be divided into two subcategories based on whether or not topographic segregation was present: (1) no significant compartmental segregation (55.9% of cases) and (2) a several-zone pattern with possible segregation (44.1% of cases). Possible compartmentalization was less clear for the IRM, which contained overlapping mixed branches between different trunks. CONCLUSION: Sihler's staining is a useful technique for visualizing the gross nerve distribution of the IRM. The new information about the nerve distribution and morphological features provided by this study will improve the understanding of the biomechanics of the IRM, and could be useful for strabismus surgery.

Location of the split line of the deep temporal fascia when reducing a zygomatic arch fracture.

BACKGROUND: The deep temporal fascia (DTF) is known to separate into two layers that descend to attach to the zygomatic arch. When surgeons reduce an isolated fracture of the zygomatic arch through a temporal approach, the temporal incision site needs to be superior to the split line of the DTF. MATERIALS AND METHODS: Sixty-seven hemifacial cadavers were investigated after removing the skin, subcutaneous tissue, and superficial temporal fascia. The superficial layer of the DTF was exposed. We cut the superficial layer along the line along, which it adhered to the deep layer inseparably. The heights of the split line of the DTF from the superior border of the zygomatic arch and from the top of the helix were measured at three points: at the jugale, zygion, and 3 cm from the tragus. RESULTS: In all cases there were thick identifiable deep layers of the DTF. The mean heights of the split line of the DTF from the superior border of the zygomatic arch were 49.8, 46.7, and 42.6 mm at the jugale, zygion, and 3 cm from the tragus, respectively; the corresponding mean heights of the split line from the top of the helix were 19.1, 15.6, and 11.4 mm. CONCLUSIONS: Knowledge of the mean height of the split line of the DTF will be helpful for surgeons to determine the temporal incision site for ensuring the safe reduction of a zygomatic arch fracture.

Location of the infraorbital foramen with reference to soft tissue landmarks for regional nerve blocks during midface surgery.

PURPOSE: An infraorbital nerve (ION) block is widely used to accomplish regional anesthesia during surgical procedures involving the midface region. This study aimed to elucidate the exact location of the infraorbital foramen (IOF) in relation to clinically useful soft-tissue landmarks for achieving an effective ION block. METHODS: Forty-three hemifaces from 23 embalmed Korean cadavers were dissected. The lateral canthus, peak of Cupid's bow, medial limbus, and midline were used as reference points. The distances from the IOF to the midline and the lateral canthus were measured. RESULTS: The IOF was located approximately 25 mm below the lateral canthus and 27 mm lateral to the midline. In all cases, the IOF was situated within 9.0 mm of the crossing point of the oblique line connecting the lateral canthus to the peak of Cupid's bow and the vertical line through the medial limbus. CONCLUSION: Considering the spread of an anesthetic agent, injecting it into the crossing point of the oblique line through the lateral canthus to the peak of Cupid's bow and the vertical line through the medial limbus would successfully block the ION in most patients.

Treatment Outcome of Modified Argon Laser Photoablation for Conjunctival Cysts.

PURPOSE: To evaluate the effectiveness of conjunctival cyst removal using a modified method of argon laser photoablation. METHODS: Seventeen cases of symptomatic conjunctival cysts were included. After staining the surface of a conjunctival cyst with a dark purple marker, the cyst was incised using a 26-gauge needle. Low-energy argon laser photoablation was then applied around the incision site for a mean of 100 times. RESULTS: During a mean follow-up period of 13.3 months (range 6-28 months), all conjunctival cysts were successfully corrected by applying either one or 2 laser sessions. Complete resolution occurred after a single laser session in 14 eyes (82.4%). There were 3 cases of recurrence with medium to large cysts, and repeating the same procedure produced surgical success in all of these cases; the conjunctival cyst recurred again after the second laser session in one of the 3 eyes, but this spontaneously regressed without further treatment. No postoperative complications such as conjunctival scarring or persistent ocular irritation were observed. CONCLUSIONS: Our modified method of argon laser photoablation uses staining of the conjunctival cyst surface to increase the amount of thermal laser energy absorbed by the target. This novel technique is simple and effective for treating conjunctival cysts in an outpatient clinic.

Topography of the Central Retinal Artery Relevant to Retrobulbar Reperfusion in Filler Complications.

BACKGROUND: Vision loss caused by retrograde occlusion of the central retinal artery is a serious complication of cosmetic filler injections. Salvage methods that involve applying hyaluronidases in the retrobulbar space to degrade filler materials have been proposed recently for rescuing the retinal circulation in an ophthalmic emergency. METHODS: Sixty-six eyeballs and orbital contents were extracted from formalin-embalmed cadavers and dissected carefully to examine the topographic relationship of the central retinal artery and optic nerve. To observe the three-dimensional course of a central retinal artery that invaginates into the optic nerve, serial sections reconstructed at 100-µm intervals using software were visualized in 11 specimens. RESULTS: The central retinal artery ramified from the ophthalmic artery and entered the optic nerve inferiorly at 8.7 ± 1.7 mm (mean ± SD) from the posterior margin of the eyeball. The intraneural course of a central retinal artery changed acutely between the periorbital environment of the fibrous optic nerve sheath, intermediate subarachnoid spaces, and center of the optic nerve stroma. CONCLUSION: When applying a retrobulbar approach for central retinal artery reperfusion with hyaluronidases, the reliable access route is suggested to be at a depth of 3.0 to 3.5 cm from the border of the inferolateral orbital rim, based on consideration of the entry point of the central retinal artery into the optic nerve.

External and Internal Diameters of the Facial Artery Relevant to Intravascular Filler Injection.

BACKGROUND: Vision loss and skin necrosis caused by an accidental intraarterial embolism or vascular compression are rare but devastating complications when injecting filler materials into the face. METHODS: The external and internal diameters and wall thicknesses of the facial artery and its branches were measured from 41 formalin-embalmed cadavers after removing connective tissues attached to the arterial wall. RESULTS: The diameter and thickness of the facial artery exhibited significant interregional differences. The external and internal diameters of the facial artery were 1.9 ± 0.4 and 1.2 ± 0.3 mm (mean ± SD), respectively, at the inferior border of the mandible; 1.7 ± 0.3 and 1.2 ± 0.3 mm in the vicinity of the inferior labial artery; 1.5 ± 0.3 and 1.0 ± 0.3 mm at the mouth corner; 1.4 ± 0.3 and 0.9 ± 0.2 mm in the vicinity of the superior labial artery; and 1.1 ± 0.2 and 0.7 ± 0.2 mm in the vicinity of the lateral nasal artery. The external and internal diameters at the proximal parts of the inferior labial artery, superior labial artery, and lateral nasal artery were 1.0 ± 0.3 and 0.6 ± 0.2 mm, 0.9 ± 0.3 and 0.6 ± 0.2 mm, and 0.8 ± 0.2 and 0.5 ± 0.2 mm, respectively. CONCLUSION: Morphometric examinations of the facial artery under stereomicroscope observation as performed in the present study are expected to be more accurate than direct measurements obtained during cadaveric dissection or conventional histologic evaluations.

Ligamentous structures in human glans penis.

The corpus spongiosum reportedly occupies a larger proportion of the human glans penis than does the penile body, embedding the end of the corpus cavernosus (CC). However, anatomic descriptions about the fibrous structures of glans penis in the literature cause confusion during dissection and reconstructive surgery. Forty-five penises of formalin-embalmed cadavers were dissected sagittally along the course of the distal urethra and observed macroscopically. Dense connective tissues adjacent to the fossa navicularis and spongiosum parts of the glans were cropped, and underwent Masson's trichrome and Verhoeff-Van-Gieson staining. Most (55.5%) of the specimens had distinct fibrous bands toward the distal tips of the glans penis, which elongated from the tunica albuginea of the CC. They comprised longitudinal collagen bundles continuous to the outer longitudinal layer of the tunica albuginea covering the CC and were intermingled with sparse elastic fibres. This architecture either did not reach the distal end of the glans penis (35.5% of cases), or was obscure or dispersed in all directions (9.0% of cases). The structural dimorphism and the variations in the ratio of dense connective tissue components of the fibrous skeleton are considered to contribute to the varying degrees of flexibility, distensibility and rigidity of the human glans penis.

Asymmetric Protrusion of the Midface in Young Adults.

PURPOSE: This study evaluated midfacial asymmetry using an alternative method that involved comparing bilateral patterns of the zygomaticomaxillary prominence in a young adult population. MATERIALS AND METHODS: Three-dimensional reconstructed images based on computed tomography scans of 100 Koreans (mean age, 24.7 years) were evaluated with reference to lines spaced at 30° intervals and radiating from the center of an interporion line in a superior view. The surface inclination of the zygomaticomaxillary region was quantified on the same reference lines using a 3-dimensional ruler. RESULTS: The 30°-interval line (at the level of the zygomaticotemporal suture) was longer on the left side than the right side in both males and females, whereas the left 60°-interval line (at the level of the zygomaticofrontal suture) was longer in females. Comparing the surface protrusion revealed that the zygomaticomaxillary region was more prognathic and inflated on the left side. CONCLUSION: Functional deviations are considered to be causes of asymmetric craniofacial growth. Postnatal growth allometry across the circummaxillary sutures as elucidated by this study could be useful information in craniofacial surgery.

Effects of ostium granulomas and intralesional steroid injections on the surgical outcome in endoscopic dacryocystorhinostomy.

PURPOSE: To determine the effect of granuloma formation in the ostium and intralesional steroid injections (ISIs) on the surgical outcome after endoscopic dacryocystorhinostomy (DCR) in patients with primary acquired nasolacrimal duct obstruction (PANDO). METHODS: One hundred and eighty-three cases involving 142 patients were enrolled. The ostium granulomas were classified according to their location relative to the internal common opening (superior, anterior, and posterior positions) and to the vicinity of the ostium (inner, edge, and extra types). If an ostium granuloma was observed during the follow-up and its size increased, ISIs were performed using 0.3 ml of 40 mg/ml triamcinolone acetonide. The surgical outcomes were compared between cases with and without ostium granulomas and also between each granuloma position and type. RESULTS: Ostium granulomas occurred in 71 (38.8%) of the 183 cases, and an ISI was applied in 65 cases with a mean of 2.1 injections. All of the granulomas regressed successfully after ISIs, with the success rate not differing between the cases with (85.9%) and without (83.9%) granuloma. There was no association between granuloma location and surgical outcome. However, the functional outcome was worse (60%) for inner granulomas (which are located within the ostial base) than for extra (87.8%) and edge (98%) granulomas. CONCLUSIONS: ISIs can be easily applied by a surgeon to help regress an ostium granuloma and improve the ostial patency after DCR. Inner ostium granulomas are associated with a worse functional outcome, and the initiation of an early corrective intervention such as an ISI should be considered.

Anatomical Consideration for the Safe Elevation of the Deep Circumflex Iliac Artery in Flap Surgery.

BACKGROUND: Deep circumflex iliac artery osteocutaneous flap transfer has frequently been applied to large defects in the maxillary and mandible regions, but the use rate has decreased gradually because of the complicated anatomy of the deep circumflex iliac artery. This study investigated the comprehensive anatomy of the deep circumflex iliac artery in relation to flap surgery with the aim of providing navigational guidelines for safe deep circumflex iliac artery harvesting. METHODS: Sixty-two sides of the hemi-abdominal wall were dissected in fixed Korean cadavers. Several dimensions of the deep circumflex iliac artery and its positional relationships with surgical landmarks were measured, and the patterns of the arterial supply and anastomosis were identified. RESULTS: The mean distance between the anterior superior iliac spine and the lateral border of the femoral artery was 57.5 mm. The deep circumflex iliac artery generally originated almost at the same level as the inguinal ligament, and its highest level was 14.8 mm superior to that ligament. Emerging points of the ascending branch were observed both medial and lateral to the anterior superior iliac spine, but no transverse branch pierced the transversus abdominis muscle medial to the anterior superior iliac spine. CONCLUSIONS: The incision line for safe deep circumflex iliac artery harvesting was parallel and 2 cm superior to the inguinal ligament and 6 cm from the anterior superior iliac spine. This position of the safe incision line can be easily determined using the thumb. Sex differences in the incidence of the deep circumflex iliac artery originating above or below the inguinal ligament will be another useful guide for easily detecting the deep circumflex iliac artery.

Surgical anatomy of the superficial temporal artery to prevent facial nerve injury during arterial biopsy.

To investigate the topographical relationship between the frontal branch of the superficial temporal artery (FSTA) and the temporal branch of the facial nerve (TFN) with the aim of preventing nerve injury during FSTA biopsy. Fifty-seven hemifaces of 33 cadavers were dissected. Vertical lines drawn to the lateral orbital margin (LOM) and the superior root of the helix were used as the anterior and posterior reference positions, respectively. Horizontal lines drawn through the supraorbital margin and lateral canthus were used as the superior and inferior reference points, respectively. The depth and course relationships of the FSTA and TFN were examined. Midpoints between the FSTA and TFN are situated approximately 6.0 and 4.5 cm posterior to the lateral orbital margin at the levels of the lateral canthus and supraorbital margin, respectively. The TFN is generally situated 1-2 cm anteriorly and inferiorly to the FSTA in the temporal region. However, in two cases (3.6%), the TFN ran just underneath the FSTA with only a very small safe distance, making it highly vulnerable to iatrogenic injury. In conclusion, when performing an FSTA biopsy, the surgeon should not dissect below the superficial temporal fascia because there is an overlap between the course of the FSTA and the TFN in a minority of cases. Also, surgical incisions should be made outside the area delineated by an oblique line passing through the points 6.0 and 4.5 cm posterior to the lateral orbital margin at the levels of the lateral canthus and the supraorbital margin, respectively. Clin. Anat. 31:608-613, 2018. © 2017 Wiley Periodicals, Inc.

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.