A Dark Side of the Cannula Injections: How Arterial Wall Perforations and Emboli Occur.

BACKGROUND: Though most injectors prefer to use a cannula rather than a needle, there have been reported cases of blindness following cannula injections. This study investigated possible situations in which a cannula can injure an artery to gain more insight about the vascular complication and its prevention. METHODS: To understand how an arterial injury occurs, five situations favoring vascular injury were simulated and tested. Experiments were performed in 100 arterial segments of 10 soft embalmed cadavers with red latex injections to the arteries. The frontal branch of the superficial temporal artery with a diameter between 1.2 and 1.5 mm was chosen for the experiment with a 25G cannula. Five situations were created to simulate any possibility that the cannula can penetrate through the arterial wall. Two factors were varied for simulation of specific danger situations. Factors that vary were as follows: (1) the angles between the cannula and the artery when the cannula touched the artery, and (2) the segments of the artery with different features. RESULTS: The cannula could penetrate the arterial wall in some specific situations with a different chance in each situation. The perpendicular angle between the artery and the cannula was one of the essential situations for vascular injury. Situations that had a similar effect of the perpendicular arterial surface related to the cannula axis also favored vascular injuries. CONCLUSION: During a blinded insertion of cannula injections to reach the target area, the injector cannot discriminate the sensation at the cannula tip between the resistance of a fibrous septum in the way of the insertion and the resistance of encountering an artery. To prevent arterial emboli, the cannula trajectory should not be close to the main artery in the region. This allows a physician to safely perform an intermittent forceful insertion without an arterial injury during an attempt to perform a gentle cannula insertion. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors. www.springer.com/00266 .

Cadaveric Assessment of Lip Injections: Locating the Serious Threats.

BACKGROUND: Lip augmentation could be a possible cause of blindness following filler injections. This study evaluated the risk by simulating clinical scenarios of marginal injections to the upper and lower lips and then evaluated the risk of vascular injuries. METHODS: A 22G cannula was inserted bilaterally along the wet-dry junction of the upper and lower lip margins in fifteen cadavers, and then both lips were dissected to verify possible injuries to the superior and inferior labial arteries. The position of the labial arteries in the vermilion zone was documented to determine the appropriate injection technique. RESULTS: In the marginal injections to the lips, arterial injuries occurred at the medial segment of the vermilion zone of both the upper and lower lips, at the terminal part of the labial arteries or a distal branch. Considering arterial anatomy, the upper lip has a higher chance of arterial injury than the lower lip. The cannula should not be inserted in the submucosa as it is recommended to evert the vermilion because both the superior and inferior labial arteries are located in the submucosa of the medial and middle segments of the vermilion in all specimens. CONCLUSION: Awareness of the possibility of vascular injury is necessary during injections of the medial segments of the vermilion of the lips. Vermilion border and marginal injections are recommended for safe and effective lip augmentation. Deep injection around the oral commissure and submucosal injection of the medial and middle segments of the vermilion zone are prohibited because of the high risk of arterial injury. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Periorbital and Intraorbital Studies of the Terminal Branches of the Ophthalmic Artery for Periorbital and Glabellar Filler Placements.

BACKGROUND: Filler injections for sunken upper eyelid correction and glabellar augmentation at the orbitoglabellar region need to be performed correctly. Precise knowledge of the emerging sites of all terminal branches of the ophthalmic artery is essential for these procedures to be conducted safely. METHODS: The terminal branches of the ophthalmic artery were studied in both periorbital and intraorbital dissections. The aim of this study was to verify the critical positions of the emerging sites at the orbital septum that may act as potential retrograde channels for filler emboli. RESULTS: In the 40 eyes examined, the branches of the ophthalmic artery were found to emerge from four different sites. Two substantial emerging sites were situated on both sides of the trochlea of the superior oblique muscle. These sites were located at the superior part of the medial orbital rim (SMOR) and are alternatively named as the epitrochlear and the subtrochlear emerging sites. The other two sites can be regarded as accessory emerging sites due to the comparably smaller artery. Dissection of the intraorbital region revealed small periosteal branches of the infraorbital artery which coursed anteriorly on the orbital floor to form anastomoses with the lacrimal artery. In other areas of the orbital floor, no branches extended from the infraorbital artery. In front of the lacrimal gland, very minute branches descended and coursed along both margins of the superior tarsus but did not course outside the lateral orbital rim. CONCLUSION: A danger zone was located at the SMOR, where the ophthalmic branches emerge to form anastomotic channels. Compression at the trochlea guarantees safe injection of filler, reducing the risk of complication. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Facing the Worst Risk: Confronting the Dorsal Nasal Artery, Implication for Non-surgical Procedures of Nasal Augmentation.

BACKGROUND: The nose is a dangerous site for filler injection. This study investigated the anatomy of the dorsal nasal artery at the upper part of the nose to clarify how ocular complications occur. METHODS: Dissections were performed in 50 noses of the embalmed cadavers. Either the soft embalming or formaldehyde embalming processes were used. RESULTS: The dorsal nasal artery is not a constant artery. The artery traveled in the subcutaneous tissue layer of the nasal dorsum on the transverse nasalis muscle and its midline nasal aponeurosis which connected the muscles on both sides. Bilateral dorsal nasal arteries existed only in 34%. In 28% of the specimens, a single and large dorsal nasal artery was presented. The diameter was 0.4 ± 0.2 mm when bilateral dorsal nasal arteries were present and 0.7 ± 0.3 mm in a single artery. The largest artery was 1.2 mm. The artery usually crossed the midline at the middle third part of the nose over the upper lateral cartilages to form an anastomosis with the contralateral lateral nasal artery as the oblique nasal artery in 14%. The artery might descend and communicate with the ipsilateral lateral nasal artery in 6% or descended as a midline artery and form the nasal tip plexus in 8%. In 38% of the specimens, the arteries became small, formed a subcutaneous plexus and randomly distributed on the superficial layer of the subcutaneous tissue in the upper two-thirds of the nose. CONCLUSION: During the injections at the upper (bony) and middle (cartilaginous) part of the nose for nasal dorsal augmentation, the injector has to make sure the cannula tip is in the preperiosteal plane by reinsertion of the cannula if needed, due to the chance of encountering the large single dorsal nasal artery at the midline. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Safe Planes for Injection Rhinoplasty: A Histological Analysis of Midline Longitudinal Sections of the Asian Nose.

BACKGROUND: Dorsal nasal augmentation is an essential part of injection rhinoplasty on the Asian nose. Aesthetic physicians require detailed knowledge of the nasal anatomy to accurately and safely inject filler. METHODS: One hundred and thirty-five histological cross sections were examined from 45 longitudinal strips of soft tissue harvested from the midline of the nose, beginning from the glabella to the nasal tip. Muscles and nasal cartilage were used as landmarks for vascular identification. RESULTS: At the nasal tip, a midline longitudinal columellar artery with a diameter of 0.21 ± 0.09 mm was noted in 14 cadavers (31.1 %). At the infratip, subcutaneous tissue contained cavernous tissue similar to that of the nasal mucosa. The feeding arteries of these dilated veins formed arteriovenous shunts, into which retrograde injection of filler may be possible. All of the nasal arteries present were identified as subcutaneous arteries. They coursed mainly in the superficial layer of the subcutaneous tissues, with smaller branches forming subdermal plexuses. A substantial arterial anastomosis occurred at the supratip region, in which the artery lay in the middle of the subcutaneous tissue at the level of the major alar cartilages. These arteries had a diameter ranging between 0.4 and 0.9 mm and were found in 29 of 45 specimens (64.4 %). This was at the level midway between the rhinion above the supratip and the infratip. This anastomotic artery also crossed the midline at the rhinion superficial to the origin of the procerus on the lower end of the nasal bone. Here the arterial diameter ranged between 0.1 and 0.3 mm, which was not large enough to cause arterial emboli. Fascicular cross sections of the nasalis muscle directly covered the entire upper lateral cartilage. The subdermal tissue contained few layers of fat cells along with the occasional small artery. The procerus arose from the nasal bone and was continuous with the nasalis in 16 cadavers (35.6 %). There was fatty areolar tissue between the procerus and the periosteal layer and no significant arteries present. The procerus ascended beyond the brow to insert into the frontalis muscle with very few cutaneous insertions. The supratrochlear vessels and accompanying nerve were occasionally found on the surface of the frontalis muscle. CONCLUSION: Most nasal arteries found in the midline are subcutaneous arteries. Filler should be injected deeply to avoid vascular injury leading to compromised perfusion at the dorsum or filler emboli at the nasal tip. LEVEL OF EVIDENCE V: This journal requires that the authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

A Cadaveric Study of the Communication Patterns Between the Buccal Trunks of the Facial Nerve and the Infraorbital Nerve in the Midface.

Most nerve communications reported in the literature were found between the terminal branches. This study aimed to clarify and classify patterns of proximal communications between the buccal branches (BN) of the facial nerve and the infraorbital nerve (ION).The superficial musculoaponeurotic system protects any communication sites from conventional dissections. Based on this limitation, the soft tissues of each face were peeled off the facial skull and the facial turn-down flap specimens were dissected from the periosteal view. Dissection was performed in 40 hemifaces to classify the communications in the sublevator space. Communication site was measured from the ala of nose.A double communication was the most common type found in 62.5% of hemifaces. Triple and single communications existed in 25% and 10% of 40 hemiface specimens, respectively. One hemiface had no communication. The most common type of communication occurred between the lower trunk of the BN of the facial nerve and the lateral labial (fourth) branch of the ION (70% in 40 hemifaces). Communication site was deep to the levator labii superioris muscle at 16.2 mm from the nasal ala. Communications between the motor and the sensory nerves in the midface may be important to increase nerve endurance and to compensate functional loss from injury.Proximal communications between the main trunks of the facial nerve and the ION in the midface exist in every face. This implies some specific functions in normal individuals. Awareness of these nerves is essential in surgical procedure in the midface.

Evidence Suggesting that the Buccal and Zygomatic Branches of the Facial Nerve May Contain Parasympathetic Secretomotor Fibers to the Parotid Gland by Means of Communications from the Auriculotemporal Nerve.

BACKGROUND: The auriculotemporal nerve is one of the peripheral nerves that communicates with the facial nerve. However, the function of these communications is poorly understood. Details of how these communications form and connect with each other are still unclear. In addition, a reliable anatomical landmark for locating these communications during surgery has not been sufficiently described. METHODS: Microdissection was performed on 20 lateral hemifaces of 10 soft-embalmed cadavers to investigate facial-auriculotemporal nerve communications with emphasis on determining their function. The auriculotemporal nerve was identified in the retromandibular space and traced towards its terminations. The communicating branches were followed and the anatomical relationships to surrounding structures observed. RESULTS: The auriculotemporal nerve is suspended above the maxillary artery in the dense retromandibular fascia behind the mandibular ramus. It forms a knot and fans out, providing multiple branches in all directions in the sagittal plane. Inferiorly, it connects the maxillary periarterial plexus, while minute branches supply the temporomandibular joint anteriorly. The larger branches mainly communicate with the branches of the temporofacial division of the facial nerve, and the auricular branches enter the fascia of the auricular cartilage posteriorly. The temporal branches and occasionally the zygomatic branches arise superiorly to distribute within the temporoparietal fascia. The auriculotemporal nerve forms the parotid retromandibular plexus through two types of communication. It sends one to three branches to join the zygomatic and buccal branches of the facial nerve at the branching area of the temporofacial division. It also communicates with the periarterial plexus of the superficial temporal and maxillary arteries. This plexus continues anteriorly along the branches of the facial nerve and the periarterial plexus of the transverse facial artery as the parotid periductal autonomic plexus, supplying the branches of the parotid duct within the loop of the two main divisions of the parotid gland. CONCLUSION: A single cutaneous zygomatic branch arising from the auriculotemporal nerve in some specimens, the intraparotid communications with the zygomatic and the buccal trunks of the facial nerve, the retromandibular communications with the superficial temporal-maxillary periarterial plexuses, and the periductal autonomic plexus between the loop of the two main facial divisions lead to the suggestion that these communications of the auriculotemporal nerve convey the secretomotor to the zygomatic and buccal branches of the facial nerve. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

An Anatomical Study of the Middle Temporal Vein and the Drainage Vascular Networks to Assess the Potential Complications and the Preventive Maneuver During Temporal Augmentation Using Both Anterograde and Retrograde Injections.

BACKGROUND: Non-thrombotic pulmonary embolism has recently been reported as a remote complication of filler injections to correct hollowing in the temporal region. The middle temporal vein (MTV) has been identified as being highly susceptible to accidental injection. METHODS: The anatomy and tributaries of the MTV were investigated in six soft embalmed cadavers. The MTV was cannulated and injected in both anterograde and retrograde directions in ten additional cadavers using saline and black filler, respectively. RESULTS: The course and tributaries of the MTV were described. Regarding the infusion experiment, manual injection of saline was easily infused into the MTV toward the internal jugular vein, resulting in continuous flow of saline drainage. This revealed a direct channel from the MTV to the internal jugular vein. Assessment of a preventive maneuver during filler injections was effectively performed by pressing at the preauricular venous confluent point against the zygomatic process. Sudden retardation of saline flow from the drainage tube situated in the internal jugular vein was observed when the preauricular confluent point was compressed. Injection of black gel filler into the MTV and the tributaries through the cannulated tube directed toward the eye proved difficult. CONCLUSION: The mechanism of venous filler emboli in a clinical setting occurs when the MTV is accidentally cannulated. The filler emboli follow the anterograde venous blood stream to the pulmonary artery causing non-thrombotic pulmonary embolism. Pressing of the pretragal confluent point is strongly recommended during temporal injection to help prevent filler complications, but does not totally eliminate complication occurrence. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266 .

A cadaveric feasibility study of the intraorbital cannula injections of hyaluronidase for initial salvation of the ophthalmic artery occlusion.

BACKGROUND: Phthisis bulbi may follow cosmetic filler injections. Early attempts to inject hyaluronidase into the orbit after detection of devastating signs and symptoms may potentially mitigate the complications. METHODS: Cannula routes along the orbital walls were studied. Depths of injections were determined in 30 dry skulls. Deep cannula insertions were carefully performed while avoiding exiting the orbit. Forty-six cadaveric orbits with intravascular latex injection were dissected to determine injection techniques, to verify structures at risk along the routes, and to evaluate substance dispersion. RESULTS: The limited depths of the superior, lateral, medial, and inferior injection routes were 4.2, 3.8, 3.6, and 2.5 cm respectively, while the orbital width was 3.9 cm. The superior parasagittal injection was effective and rarely tears the superior ophthalmic vein, artery, and the optic nerve. The medial injection should be avoided because it may injure the lacrimal sac, the ophthalmic artery, and the optic nerve. Without limited depth, the lateral injection may damage the lacrimal gland and artery and proceeds to damage the optic nerve. The inferior parasagittal injection tends to exit into the infratemporal fossa but the inferior oblique injection may be safer and effective but more complicate with the depth of 4.2 cm. CONCLUSION: The superior parasagittal injection is a recommended simple technique with a minimal chance of vascular injury. The inferior oblique injection requires more skill but it may be safer because of the lower position. For safety reasons, depth of each cannula insertion should not exceed the orbital width. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern BasicScience, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266.

Verification of Embolic Channel Causing Blindness Following Filler Injection.

BACKGROUND: Ocular complications following cosmetic filler injections are serious situations. This study provided scientific evidence that filler in the facial and the superficial temporal arteries could enter into the orbits and the globes on both sides. We demonstrated the existence of an embolic channel connecting the arterial system of the face to the ophthalmic artery. METHODS: After the removal of the ocular contents from both eyes, liquid dye was injected into the cannulated channel of the superficial temporal artery in six soft embalmed cadavers and different color dye was injected into the facial artery on both sides successively. The interior sclera was monitored for dye oozing from retrograde ophthalmic perfusion. RESULTS: Among all 12 globes, dye injections from the 12 superficial temporal arteries entered ipsilateral globes in three and the contralateral globe in two arteries. Dye from the facial artery was infused into five ipsilateral globes and in three contralateral globes. Dye injections of two facial arteries in the same cadaver resulted in bilateral globe staining but those of the superficial temporal arteries did not. Direct communications between the same and different arteries of the four cannulated arteries were evidenced by dye dripping from the cannulating needle hubs in 14 of 24 injected arteries. Compression of the orbital rim at the superior nasal corner retarded ocular infusion in 11 of 14 arterial injections. CONCLUSION: Under some specific conditions favoring embolism, persistent interarterial anastomoses between the face and the eye allowed filler emboli to flow into the globe causing ocular complications.

A typical pattern of the labial arteries with implication for lip augmentation with injectable fillers.

BACKGROUND: Anatomical knowledge of the vascular supply to the upper- and lower-lip vermilion is essential for lip augmentation. METHODS: The soft tissues of the whole face, including arterial latex injection, were peeled off as a facial flap and turned down for dissection. The mucosal flap was elevated away from the orbicularis oris muscle and the lower facial musculature. The superior and inferior labial arteries were traced from the facial artery along the course of the vermilion. RESULTS: The facial artery branched into the superior labial artery just above the labial commissure. This artery ran 4.5 mm deep along the upper lip between the oral mucosa and the orbicularis oris muscle just above the vermilion-mucosa junction to anastomose with the opposing artery. The inferior labial artery originated as a common trunk along with the labiomental artery once the facial artery entered the oral vestibule deep to the platysma muscle. The main arterial trunk coursed along the alveolar border within the plane between the orbicularis oris muscle and the lip depressors. From the arterial trunk emanated the inferior labial artery, which accompanied the mental nerve to the lower lip. CONCLUSION: The vermilion borders of the upper and lower lips are safe for superficial filler injection. All areas of the lower lip are safe because of the minute size of the ascending arteries. To achieve a full upper lip, filler should be injected into the middle body of the lip, thereby avoiding deep injection between the muscle layer and the mucosa, minimizing the risk of injury to the anastomotic arch of the superior labial arteries. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266.

An anatomic basis for treatment of retinal artery occlusions caused by hyaluronic acid injections: a cadaveric study.

BACKGROUND: In ophthalmic artery occlusion by hyaluronic acid injection, the globe may get worse by direct intravitreal administration of hyaluronidase. Retrograde cannulation of the ophthalmic artery may have the potential for restoration of retinal perfusion and minimizing the risk of phthisis bulbi. The study investigated the feasibility of cannulation of the ophthalmic artery for retrograde injection. METHODS: In 10 right orbits of 10 cadavers, cannulation and ink injection of the supraorbital artery in the supraorbital approach were performed under surgical loupe magnification. In 10 left orbits, the medial upper lid was curvedly incised to retrieve the retroseptal ophthalmic artery for cannulation by a transorbital approach. Procedural times were recorded. Diameters of related arteries were bilaterally measured for comparison. Dissections to verify dye distribution were performed. RESULTS: Cannulation was successfully performed in 100 % and 90 % of the transorbital and the supraorbital approaches, respectively. The transorbital approach was more practical to perform compared with the supraorbital approach due to a trend toward a short procedure time (18.4 ± 3.8 vs. 21.9 ± 5.0 min, p = 0.74). The postseptal ophthalmic artery exhibited a tortious course, easily retrieved and cannulated, with a larger diameter compared to the supraorbital artery (1.25 ± 0.23 vs. 0.84 ± 0.16 mm, p = 0.000). CONCLUSIONS: The transorbital approach is more practical than the supraorbital approach for retrograde cannulation of the ophthalmic artery. This study provides a reliable access route implication for hyaluronidase injection into the ophthalmic artery to salvage central retinal occlusion following hyaluronic acid injection. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266.

Snake scope camera assisted endotracheal intubation: a procedural skills training in cadaver to prepare preclinical students for their clerkships.

OBJECTIVE: Preparing students to perform specific procedures on patients presents a challenge of student confidence in performing these tasks. This descriptive study determined the ability of the medical students to perform a basic clinical task after a short hands-on training workshop in cadavers. This basic procedural skills training was an attempt for developing conceptual understanding and increasing procedural skills in endotracheal intubation of the medical students. MATERIAL AND METHOD: The students were trained to perform two different endotracheal intubations, uncomplicated intubation, and a traumatic difficult airway scenario. The training session consisted of two methods of endotracheal intubation, oral intubations using direct laryngoscopy (DL) in two cadavers with uncomplicated airway and the Flexible Snake Scope camera (FSSC) assisted nasal intubation procedures in two cadavers simulated trauma victims with difficult airway. In the assessment session, the students performed one timed trial with each device. All four cadavers were changed but the scenarios were the same. The groups of the medical students were randomly assigned to perform the tasks in one of two cadavers of the two scenarios. RESULTS: Thirty-two medical students participated in this training and assessment. The training session and the assessment lasted five hours and three hours respectively. No student was asked to perform the second trial. The average time for successful intubation with DL was 32.7 seconds (SD, 13.8 seconds) and for FSSC was 127.0 seconds (SD, 32.6 seconds). The intubation failure rate was 0% for the entire study. CONCLUSION: The medical students have the ability to accomplish a basic clinical task after a short hands-on training workshop.