Nerve Wrap for Local Delivery of FK506/Tacrolimus Accelerates Nerve Regeneration

Peripheral nerve injuries (PNIs) occur frequently and can lead to devastating and permanent sensory and motor function disabilities. Systemic tacrolimus (FK506) administration has been shown to hasten recovery and improve functional outcomes after PNI repair. Unfortunately, high systemic levels of FK506 can result in adverse side effects. The localized administration of FK506 could provide the neuroregenerative benefits of FK506 while avoiding systemic, off-target side effects. This study investigates the utility of a novel FK506-impregnated polyester urethane urea (PEUU) nerve wrap to treat PNI in a previously validated rat infraorbital nerve (ION) transection and repair model. ION function was assessed by microelectrode recordings of trigeminal ganglion cells responding to controlled vibrissae deflections in ION-transected and -repaired animals, with and without the nerve wrap. Peristimulus time histograms (PSTHs) having 1 ms bins were constructed from spike times of individual single units. Responses to stimulus onsets (ON responses) were calculated during a 20 ms period beginning 1 ms after deflection onset; this epoch captures the initial, transient phase of the whisker-evoked response. Compared to no-wrap controls, rats with PEUU-FK506 wraps functionally recovered earlier, displaying larger response magnitudes. With nerve wrap treatment, FK506 blood levels up to six weeks were measured nearly at the limit of quantification (LOQ ≥ 2.0 ng/mL); whereas the drug concentrations within the ION and muscle were much higher, demonstrating the local delivery of FK506 to treat PNI. An immunohistological assessment of ION showed increased myelin expression for animals assigned to neurorrhaphy with PEUU-FK506 treatment compared to untreated or systemic-FK506-treated animals, suggesting that improved PNI outcomes using PEUU-FK506 is mediated by the modulation of Schwann cell activity.

Topography of the infraorbital foramen in human skulls originating from different time periods

BACKGROUND

The infraorbital foramen (IOF) is present on the maxilla under the infraorbital margin. Its identification is essential in various surgical procedures. The main aim of this study was the morphometric assessment of the position of the right and left infraorbital foramina in relation to specific structural elements of the facial skeleton, their width and direction, and also the determination of the location of these foramina above maxillary teeth in examined male skulls (belonging to European populations) dated to the beginning of the 20th century and the medieval and post-medieval period. This aim concerned also the assessment of the symmetry of the examined foramina (their location and size). An additional goal was to determine differences between the cranial samples concerning the analysed traits.

MATERIALS AND METHODS

The six metric and two non-metric traits concerning the IOF were collected from the male cranial samples including modern skulls (n = 87), the medieval and post-medieval skulls (from 13th centuries and 15-17th centuries, respectively; n = 47) obtained from archaeological excavations in Wroclaw, and the sample of the medieval skulls (11-13th centuries, n = 100) from Sypniewo. The sex and age of the specimens were determined using the standard methodology. The appropriate statistical analysis was performed.

RESULTS

Significant differences were established for three traits (taken from the left and right side) in the case of modern skulls (diameter of IOF, its distance to the midline, and zygomaticomaxillary suture) and one in the case of medieval skulls from Sypniewo (distance to the midline). In all of the cranial samples IOF most frequently occurred above the first upper molar. The greater diameter of IOF and its shorter distance to the alveolar crest and nasal notch were observed in non-modern skulls compared to modern skulls.

CONCLUSIONS

The results of this study provide new additional data on the topography of IOF and its asymmetry, confirm the presence of both geographical and chronological differences between populations, and can be used in dental practice, and forensic odontology in the analysis of archaeological bone materials.

Nasal Herpes Simplex With Infraorbital Neuralgia: A Rare Presentation

Facial herpes is a form of herpes simplex type I infection and presents with characteristic vesicular lesion around the perioral region. Nasal herpes, a form of facial herpes is a rare presentation with only a few cases reported in the literature. Neuralgic pain in herpes simplex is usually experienced at the site of the lesion during or before the eruptive stage. Here, we are reporting a case where the patient with a herpes simplex lesion over the tip of her nose presented with pain over the infraorbital region, which is a region supplied by the infraorbital nerve, a branch of the maxillary division of the trigeminal nerve. Initially confused as a bacterial infection due to its unusual presentation and rarity of the condition, the patient was given anti-bacterial therapy, but on showing no relief in symptoms, the patient was treated with appropriate antiviral drugs, following which complete remission of the lesion was observed. The case highlights a rare site for a common condition and atypical presentation.

Extended Endoscopic Pre-Lacrimal Medial Maxillectomy To the Anterior Maxillary Sinus Wall

Endoscopic pre-lacrimal medial maxillectomy involving the resection of the antero-medial maxillary sinus wall is a novel expanded procedure that allows the management of far lateral or antero-medial benign pathologies of the maxillary sinus, without increasing peri-operative morbidity. Laryngoscope, 133:2874-2877, 2023.

Morphological and Morphometric Relations of Infraorbital Foramen in North Indian Population

Introduction The evidence regarding the anatomy of the infraorbital foramen in the Indian population is limited. It mainly focuses on its shape, size, and incidence in the Indian population. The current study aimed to evaluate morphometric parameters of infraorbital foramen that can help clinicians during surgery and procedures around it. Methods We evaluated 90 dry adult human hemi-skulls. The morphological parameters studied included the assessment of the shape of the infraorbital foramen, its horizontal and vertical diameters, and its relation to the teeth of the upper jaw. In addition, we measured the distance of the infraorbital foramen from the anterior nasal spine, nasion, infraorbital margin, and the lower extent of the alveolar margin. The length of the infraorbital canal till the inferior orbital fissure and the infraorbital groove and the infraorbital canal orientation angles in different planes were also measured. The measurement values were compared between the right and left side hemi-skulls. Results The oval-shaped infraorbital foramen was most commonly noticed. The mean vertical and transverse diameters were 3.8 mm and 2.6 mm, respectively, on the right side. The left side's mean vertical and transverse diameters were 3.9 mm and 2.5 mm, respectively. The most common location of infraorbital foramen was in line with the maxillary second premolar tooth. The distances of infraorbital foramen from the alveolar margin were 29.6 mm and 29 mm on the right and left sides, respectively. The distances of the infraorbital foramen from the anterior nasal spine were 34.3 mm and 34.2 mm on the right and left sides, respectively. The distances of infraorbital foramen from the nasion were 42.3 mm and 42.2 mm on the right and left sides, respectively. The distances of infraorbital foramen from the inferior orbital margin were 5.8 mm and 6.2 mm on the right and left sides, respectively. The distances between the inferior orbital margin and infraorbital groove were 12.7 mm and 12.7 mm on the right and left sides, respectively. The distances between the inferior orbital margin and inferior orbital fissure were 27.5 mm and 27.1 mm on the right and left sides, respectively. The orientation angles of infraorbital foramen were 48.31° in the horizontal plane, 34.07° in the Frankfurt plane, and 14.4° in the parasagittal plane. Conclusion Our findings suggest that the location of the infraorbital foramen is difficult to standardize, considering the wide interindividual variations in the foramen relations. Further research should be performed to investigate the parameters related to the distance and orientation of the infraorbital foramen in relation to nearby bony landmarks that are least affected by individual variations in skull morphology.

Establishment of a Rat Model of Infraorbital Neuroinflammation Under CT Guidance

INTRODUCTION

The aim is to establish a rat model of infraorbital neuroinflammation with less trauma, stable pain, and a long duration of pain. The pathogenesis of TN is not fully clear. There are various models of TN in rats with different disadvantages, such as damaging the surrounding structures and inaccuracy of location for infraorbital nerve (ION). We aim to establish a rat model of infraorbital neuroinflammation with minimal trauma, a simple operation, and accurate positioning under CT guidance to help us study the pathogenesis of trigeminal neuralgia.

METHODS

Thirty-six adult male Sprague Dawley rats (180-220 g) were randomly divided into 2 groups and injected with talc suspension or saline through the infraorbital foramen (IOF) under CT guidance. Mechanical thresholds were measured in the right ION innervation region of 24 rats over 12 postoperative weeks. At 4 weeks, 8 weeks, and 12 weeks after the operation, the inflammatory involvement of the surgical area was evaluated by MRI, and neuropathy was observed using a transmission electron microscope (TEM).

RESULTS

The talc group had a significant decrease in the mechanical threshold at 3 days after surgery that continued until 12 weeks post-operation, and the talc group had a significantly lower mechanical threshold than the saline group 10 weeks post-operation. The talc group had significantly impaired trigeminal nerve (TGN) myelin after 8 weeks post-operation.

CONCLUSION

The rat model of infraorbital neuroinflammation established by CT-guided injection of talc into the IOF is a simple operation that results in less trauma, stable pain, and a long duration of pain. Moreover, infraorbital neuroinflammation in peripheral branches of the TGN can cause demyelination of the TGN in the intracranial segment.

Investigating the relationship between infraorbital canal morphology and maxillary sinus size

The purpose of the current study was to investigate relationships between maxillary sinus (MS) dimensions and the bony structures associated with the infraorbital nerve (ION). Computed tomographic scans of 87 adult crania (174 sides) from four morphologically diverse groups (West Africans, East Africans, North Asians, Europeans) were utilized. Seven primary variables were collected: infraorbital canal (IOC) type; infraorbital foramen (IOF) shape; distance from the foramen rotundum to IOF (FR-IOF); distance from the posterior wall of the infraorbital groove to IOF (IOG-IOF); and MS length, breadth, and height. Chi-square analyses indicated a significant association between IOC-type and IOF-shape (Pearson chi-square = 12.710; p-value = .013), with the most common pattern being oval IOFs and Type-I IOCs (45.68% of the sample; 74/162 sides). Analysis of covariance indicated a significant effect of ancestry (F = 8.333; p < .001) and MS length (F = 15.406; p < .001) on IOG-IOF distance. Ordinal regression analyses indicated that MS length (Wald chi-square = 7.103; p = .008) also maintained a significant effect on IOC-type, while multinominal regression analyses indicated that none of the measured parameters had a significant effect on IOF-shape. These results have clinical implications: recognizing IOC-type and IOF-shape relative to the MS is important to avoid ION damage during medical procedures. Overall, this study found most individuals possess Type-I IOCs (housed in the maxillary sinus roof) and oval-shaped IOFs. Most aspects of the ION pathway, including IOC-type and IOF-shape, were not influenced by ancestry or sex. However, antero-posteriorly longer MSs tend to possess Type-III IOCs protruding into the sinus, which could lead to surgical complications.

Stem cells from human exfoliated deciduous teeth relieve pain via downregulation of c-Jun in a rat model of trigeminal neuralgia

BACKGROUND

Stem cells from human exfoliated deciduous teeth (SHED) have excellent immunomodulatory and neuroprotective abilities. It is possible that systemic SHED transplantation could ameliorate trigeminal neuralgia. The phosphorylation of c-Jun contributes to the development of hyperalgesia and allodynia.

OBJECTIVE

The present study aimed to evaluate whether systemic SHED transplantation could lead to analgesic effects by regulating peripheral c-Jun in the trigeminal ganglia (TG) in a rat model of trigeminal neuralgia.

METHODS

Chronic constriction injury of the infraorbital nerve (CCI-ION) was performed to establish a rat pain model. SHED were obtained from discarded exfoliated deciduous teeth from children and transplanted by a single infusion through the tail vein. SHED were labelled with the PKH26 red fluorescent cell linker mini kit for tract distribution. The mechanical threshold was determined using von Frey filaments. The mRNA levels of c-Jun in the ipsilateral TG were quantified. The phosphorylation of c-Jun in the ipsilateral TG was assessed by immunohistochemistry and Western blotting.

RESULTS

PKH26-labelled SHED were distributed to both sides of TG, lung, liver and spleen. Systemic SHED transplantation significantly elevated the mechanical thresholds in CCI-ION rats and blocked the upregulation of c-Jun mRNA levels in the TG caused by nerve ligation. The activation of c-Jun in the TG was blocked by SHED transplantation.

CONCLUSIONS

These findings demonstrate that systemic SHED administration reverts trigeminal neuralgia via downregulation of c-Jun in the TG.

Comparison of three regional anaesthetic techniques for infraorbital or maxillary nerve block in cats: a cadaveric study

Objectives

The maxillary nerve courses very close to the globe, rendering cats – with their large eyes – at risk of globe penetration during infraorbital or maxillary nerve blocks. Therefore, the goals of the study were to compare the distribution and potential complications of three infraorbital or maxillary regional injection techniques.

Methods

Twenty-three bilateral maxillae of cat cadavers were used in a randomised blinded trial. Each maxilla was injected with a 0.2 ml 1:1 mixture of lidocaine 2% and a contrast medium by one of three injection techniques: infraorbital foramen (IOF; n = 14); infraorbital canal (IOC; n = 16); or maxillary foramen (MF; transpalpebral approach; n = 16) using a 25 G 1.6 cm needle. CT imaging of each cadaver head was performed before and after injections. A radiologist scored injectate distribution (none [0], mild [1], moderate [2], large [3]) in four locations: rostral, central and caudal IOC, and at the MF, for which the distribution side was also determined. Comparisons were performed with ordinal logistic mixed effects (P <0.05).

Results

The median (range) total distribution score of the IOC and MF technique were significantly higher compared with the IOF technique (6.5 [4–12], 4 [2–8] and 0 [0–10], respectively). The total IOC score was also significantly higher compared with the MF technique. Injectate distribution at the MF was significantly more central following IOC injection compared with MF injection, which distributed centrolaterally. None of the techniques resulted in intraocular injection.

Conclusions and relevance

The IOC and MF techniques produced a satisfactory spread of the mixture that could result in effective maxillary anaesthesia in cats. Further studies are required to determine the effectiveness and safety of these techniques.

Peripheral Neurectomy for Trigeminal Neuralgia: A Report of Seventeen Cases and Review of the Literature

Background:

Surgical intervention for trigeminal neuralgia (TN) is indicated if there is a failure of the medical treatment. Peripheral neurectomy is one of the oldest surgical procedures for TN.

Objective:

The aim is to evaluate the clinical outcome and the recurrence rate following peripheral neurectomy for the management of TN.

Patients and Methods:

This was a retrospective cohort study of 17 patients with classical TN treated by peripheral neurectomy. The visual analogue scale (VAS) was used for pain assessment preoperatively and during the follow-up period. The outcome of surgery was graded as a marked, moderate, or mild improvement. Kaplan–Meier analysis was used for the time to recurrence to predict the probability of recurrence at any given time following the procedure.

Results:

The mean pain-free interval was 29.3 ± 16.3 months. At 2 and 5 years of the follow-up period, the mean VAS improved significantly (P < 0.001 and P = 0.042 respectively). Thirteen patients had marked improvement of pain. There was recurrence of pain in 4 patients (23.5%). By Kaplan–Meier analysis, the survival rate without recurrence at 2, 3, 4, and 5 years following the procedure were 92.9%, 79.6%, 59.7%, and 29.8%, respectively. The mean preoperative Hospital Anxiety and Depression Scale-Anxiety and Depression scores significantly improved on the last follow-up visit following the procedure (P < 0.001 for both).

Conclusion:

Peripheral neurectomy provides short to medium-term good pain control for patients with TN. The preoperative severity of pain, anxiety, and depression levels improved markedly after the procedure.

Efficacy of exenatide, ozone, and methyl prednisolone for the recovery of infraorbital nerve paresthesia after injury in rats

BACKGROUND

Infraorbital nerve injury often occurs due to zygomatic complex fracture. There is no standard protocol to restore the sensory and motor function of the nerve after injury. Some medications are used to improve nerve function. This histopathological animal study aimed to assess the neurotrophic efficacy of exenatide, ozone, and methyl prednisolone for injured infraorbital nerve.

MATERIALS AND METHODS

In this animal study, 60 rats were randomly divided into five groups (n = 12) of control, saline, methyl prednisolone, exenatide, and ozone. Under general anesthesia, a unilateral infraorbital incision was made, and the nerve was compressed with a hemostat for 5 s. Depending on the study group, the rats received the designated medications. All rats were sacrificed after 14 days, and the nerve recovery was evaluated by observing the slides prepared from the area under a light microscope using histological and immunohistochemical parameters. Data were analyzed using Chi-square test and Tukey's least significant difference test (P < 0.05).

RESULTS

No inflammation in the peripheral tissue had a significantly higher frequency in the methyl prednisolone group (P < 0.05). Degeneration, intracellular inflammatory infiltrate, muscle injury, fibrosis around the nerve, granulation tissue, vascular proliferation, and infiltration of inflammatory cells around the nerve were more commonly absent in the exenatide group (P < 0.05).

CONCLUSION

Exenatide showed superior efficacy for the recovery of infraorbital nerve function after injury. Thus, it may be beneficial for postoperative care following infraorbital nerve injury.

A direct transcutaneous approach to infraorbital nerve biopsy

Purpose: To describe a novel transcutaneous infraorbital nerve biopsy technique which can be performed to aid in the diagnosis of perineural invasion (PNI) of facial cutaneous squamous cell carcinoma (SCC).Methods: A single-center retrospective chart review was performed. Patients diagnosed with SCC with PNI via an infraorbital nerve biopsy between February 2019 and February 2020 were included. Data collected consisted of patient demographics, medical history, clinical presentation and exam, histologic and radiographic findings, treatment, and outcomes.Results: Four patients (3 male, 1 female) met inclusion criteria. The mean age at diagnosis was 79.5 years (range 66-85 years). Three of the four patients had a history of facial skin lesions, including actinic keratosis and SCC, involving the nose, cheek, or ear. One patient had no history of cutaneous malignancy. All patients presented with cranial neuropathies, including total V2 hypoesthesia. The most common presenting symptom was facial pain, followed by diplopia, unilateral facial weakness, and hypoesthesia in the V1 and/or V2 distribution. Transcutaneous infraorbital nerve biopsy in all patients revealed squamous cell carcinoma with no biopsy complications.Conclusion: Definitive diagnosis of PNI can be challenging but is important to minimize tumor-related morbidity. Infraorbital nerve biopsy can establish this diagnosis, especially in the context of negative or indeterminate imaging findings. This work comprises the first description of a transcutaneous approach to infraorbital nerve biopsy, which is a minimally invasive technique that can be performed in an outpatient procedure suite with limited to no sedation.

Endoscopic transorbital ligation of the maxillary artery through the inferior orbital fissure

OBJECTIVE

Determine the feasibility of accessing the internal maxillary artery (IMA) through a transorbital endoscopic assisted approach through the inferior orbital fissure (IOF).

MATERIALS AND METHODS

Six adult cadaveric specimens were injected intravascularly with colored latex and dissected on 12 sides. A transorbital endoscopic approach was used to expose the IOF and reach the IMA.

RESULTS

The average length and width of the anterolateral segment of the IOF were 7.3 and 4 mm, respectively, on the right side and 6.7 and 3.8 mm, respectively, on the left side. Surgical exposure and modification of the IOF allowed the exposure and control of the IMA in all 12 sides.

CONCLUSIONS

The IOF is a feasible portal to the IMA. The benefits of this approach include vascular control of the distal segment of the maxillary artery. It may provide access in clinical scenarios where endonasal access is not possible (e.g., extensive tumors) or serve as an alternative or complementary surgical route (e.g., control during a total or radical maxillectomy).

Transantral intraseptal sinuous canal

The sinuos canal is an anatomically well-defined intramural canal of the maxillary sinus (MS) folded within the antral walls. Commonly, its first, infraorbital part, courses within the antral roof, while its second, transverse facial part courses below the infraorbital foramen within the anterior antral wall. While retrospective files of patients that were scanned in Cone Beam Computed Tomography (CBCT) for different dental medical purposes were observed randomly, a peculiar variant of the sinuous canal was noticed and further documented. The respective canal origin was far posterior in the infraorbital groove and the canal coursed through the MS embedded within an incomplete oblique septum dividing the antrum into anterosuperior and posteroinferior chambers. Then the sinuous canal continued with the transverse facial segment. As the sinuous canal contains the superior anterior alveolar nerve and artery, major suppliers of the frontal teeth, it is recommended to document in CBCT a possible transantral, and not intramural, course of it, especially when surgical or endoscopic corridors through the MS are planned.

Does the Lag Time Between Injury and Treatment Affect Recovery of Infraorbital Nerve Disturbances in Zygomaticomaxillary Complex Fractures?

Study Design

A cross-sectional study.

Objective

Neurosensory disturbances (NSDs) of the infraorbital nerve (ION) are common following orbito-zygomaticomaxillary complex (ZMC) fractures. This study aimed to evaluate the effect of lag time between injury and treatment on recovery of NSDs of the ION following open reduction internal fixation.

Methods

Subjects who had ZMC fracture and paresthesia were studied. The lag time between injury and treatment was considered as the predictive factor. The level of NSDs according to the brush test and two-point discrimination (TPD) test and self-reported NSD were the outcomes of this study. Self-reported NSD was quantified using a visual analog scale.

Results

Forty patients were studied. The lag time between injury and treatment had a significant correlation with the result of the TPD test and the self-reported level of NSD. In 73.6% of patients who had NSD following ZMC fracture, every 1-day delay in treatment increased the incidence of self-reported paresthesia by 0.44.

Conclusions

It seems, a delay in treatment of ZMC fractures increased the risk of NSD.

Dopaminergic Modulation of Orofacial Mechanical Hypersensitivity Induced by Infraorbital Nerve Injury

While the descending dopaminergic control system is not fully understood, it is reported that the hypothalamic A11 nucleus is its principle source. To better understand the impact of this system, particularly the A11 nucleus, on neuropathic pain, we created a chronic constriction injury model of the infraorbital nerve (ION-CCI) in rats. ION-CCI rats received intraperitoneal administrations of quinpirole (a dopamine D2 receptor agonist). ION-CCI rats received microinjections of quinpirole, muscimol [a gamma-aminobutyric acid type A (GABA_A) receptor agonist], or neurotoxin 6-hydroxydopamine (6-OHDA) into the A11 nucleus. A von Frey filament was used as a mechanical stimulus on the maxillary whisker pad skin; behavioral and immunohistochemical responses to the stimulation were assessed. After intraperitoneal administration of quinpirole and microinjection of quinpirole or muscimol, ION-CCI rats showed an increase in head-withdrawal thresholds and a decrease in the number of phosphorylated extracellular signal-regulated kinase (pERK) immunoreactive (pERK-IR) cells in the superficial layers of the trigeminal spinal subnucleus caudalis (Vc). Following 6-OHDA microinjection, ION-CCI rats showed a decrease in head-withdrawal thresholds and an increase in the number of pERK-IR cells in the Vc. Our findings suggest the descending dopaminergic control system is involved in the modulation of trigeminal neuropathic pain.

Endoscopic prelacrimal approach to lateral recess of sphenoid sinus: feasibility study

BACKGROUND

Various pathologies, including cerebrospinal fluid leaks and meningoencephaloceles, may arise in the lateral recess of the sphenoid sinus (LRSS), which may be accessed via an endonasal transpterygoid approach. The objective of this study was to evaluate the feasibility of accessing the LRSS via an endoscopic prelacrimal approach. Furthermore, we hypothesized that this approach may protect the pterygopalatine ganglion and vidian nerve.

METHODS

Five cadaveric heads (9 sides) with a well-pneumatized LRSS were identified and an endonasal prelacrimal approach was performed. The infraorbital nerve, at the orbital floor, served as a critical landmark. After identification of the foramen rotundum at the pterygoid base, the vascular compartment of the pterygopalatine fossa and the pterygopalatine ganglion were displaced inferomedially and superomedially, respectively. Drilling of the bone inferomedial to the foramen rotundum allowed entry into the LRSS.

RESULTS

The average distances from the prelacrimal window to the pterygoid base and the posterior wall of the LRSS were 6.22 ± 0.39 cm and 7.16 ± 0.50 cm, respectively. The average areas of the bony prelacrimal window and pterygoid base window were 4.33 ± 0.32 cm² and 0.73 ± 0.10 cm² , respectively. The LRSS could be accessed using a 0-degree endoscope, and pterygopalatine neurovascular structures, including the pterygopalatine ganglion and vidian nerve, could be preserved on all 9 sides.

CONCLUSION

Our findings suggest that an endonasal prelacrimal approach provides a reasonable alternative to access the LRSS while preserving the vidian nerve and pterygopalatine ganglion.

Three-dimensional anatomy of the transantral intraseptal infraorbital canal with the use of cone-beam computed tomography

The transantral or ectopic infraorbital canal (IOC) courses diagonally through the maxillary sinus (MS), thereby being exposed to risk during a number of surgical procedures. A few prior reports have presented evidence of a septa-embedded IOC, albeit only on single-plane slices. We identified this extremely rare variation of the IOC during a retrospective study of the cone-beam computed tomography files of 2 patients. In the first case, which involved a 34-year-old female patient, the canals and septa within the MS were bilaterally asymmetrical. On the right side, the sinus roof was attached to a short transverse septum that was traversed by the IOC, while the left sinus featured an oblique large septum that divided it into antero-superior and posterior chambers. The left IOC was embedded within the septum rather than within the orbital floor above the septum. In the second case, which concerned a 36-year-old male patient, the left MS featured an almost completely oblique/vertical septum that divided it into anterior and posterior chambers and also embedded the respective IOC, which was thus absent from the orbital floor. In both cases, infraorbital recesses in the anterior chambers of the MS were found that, if not documented on three-dimensional (3D) renderisations, could have been misidentified as infraorbital (Haller) cells. To the best of our knowledge, this is the first report to document the 3D anatomy of an extremely rare variant, namely a septum-embedded transantral IOC. Such a variant, if not adequately documented preoperatively, could divert the transmaxillary corridors down false paths or else expose the IOC to damage during surgical procedures involving access to tumours.

Anatomical Variants of the Infraorbital Canal: Implications for the Prelacrimal Approach to the Orbital Floor

Background

The infraorbital nerve (ION) and its canal are important landmarks during surgical approaches to the orbital floor and pterygopalatine fossa. However, variations in the anatomy of the infraorbital canal and its corresponding neurovascular bundle may impact the access.

Objective

To investigate anatomic variants of the infraorbital canal from a prelacrimal endoscopic perspective and to explore the impact of these variants on exposing the lateral orbital floor.

Methods

Ten cadaveric specimens (20 sides) were dissected through an endonasal prelacrimal approach. Anatomic variants of the ION including location, branching pattern, and relationship to the infraorbital artery were assessed. The need for ION transposition to increase exposure of the lateral orbital floor was also investigated.

Results

Incidence of previously described Types 1, 2, and 3 ION variants were 30.0%, 60.0%, and 10.0%, respectively. Although the orbital floor could be directly accessed in Type 1 and Type 3 IONs, transposition of the ION was necessary to expose the lateral orbital floor in 5 of 12 sides (42%) for Type 2 ION. Bony dehiscence of the orbital floor was identified in 8 of 20 sides (40%) and branching of the ION in 2 of 20 sides (10%).

Conclusion

Anatomic variations of the infraorbital canal impact surgical exposure of the orbital floor via a prelacrimal approach. Type 1 and Type 3 ION variants allow a direct exposure of the entire orbital floor. A Type 2 ION may require transposition of the nerve to adequately expose the lateral orbital floor.

Early recovery of neuronal functioning in the sensory cortex after nerve reconstruction surgery

BACKGROUND

Nerve reconstructive surgery induces a transient loss and a prolonged and a gradual return of sensory inputs to the brain. It is unknown whether, following this massive peripheral denervation, the brain will experience a prolonged period of severe, intrinsic dysfunction.

OBJECTIVE

We aim to investigate the mechanisms of return of processing function in cortical neurons.

METHODS

We used the whisker model in rats to evaluate the functional recovery in the somatosensory cortex after a nerve reconstruction surgery. Multi-unit recording in the barrel cortex was performed in lightly anesthetized rats while their whiskers were stimulated by a whisker stimulator.

RESULTS

We observed a loss of neuronal responses to whisker stimulation 1 week after surgery, which started to recover 2 weeks after surgery. Following the surgery, only 11.8% of units had principle whiskers (PWs) returned to their original status while 17.7% had PWs different from their original status, indicating the effect of aberrant reinnervation on the whisker response map.

CONCLUSIONS

Robust neuronal responses to sensory stimulation even when only sparse sensory inputs are available in the early recovery phase. During this phase, aberrant reinnervation induces disorganized whisker tuning, a finding that might be account for the hypoesthesia and paresthesia during early recovery after nerve reconstruction.

Efficacy of CT Guided Pulsed Radiofrequency Treatment for Trigeminal Postherpetic Neuralgia

Objectives

Trigeminal postherpetic neuralgia (TPHN) often presents with moderate to severe pain, hyperalgesia, and allodynia. Conventional analgesic treatments are poorly effective, which seriously affects the quality of life. This retrospective study aimed to evaluate the efficacy of pulsed radiofrequency (PRF) for the treatment of TPHN.

Methods

A total of 90 TPHN patients were selected between January 2014 and December 2016 in the Department of Pain Management, Shengjing Hospital, China Medical University. Patients were randomly divided into two groups according to the order of enrollment (n = 45 per group): group A, peripheral nerve (supraorbital nerve, infraorbital nerve and mental nerve) PRF; group B, gasserian ganglion PRF. Follow-up assessments of visual analogue scale (VAS) pain assessment, SF-36 health status questionnaire, total efficiency rate, and drug dosage of anticonvulsants and opioid analgesics were performed at time points of 1 week, 1 month, 3 months, 6 months, and 1 year after surgery.

Results

At each postsurgery time point, the VAS decreased, SF-36 (physical and mental components) increased, and drug dosage of anticonvulsants and opioids analgesics decreased in both treatment groups; values at each time point were significantly different from presurgery values (P < 0.05). Compared with group A, VAS decreased, SF-36 increased, and dosage of anticonvulsants and opioids analgesics decreased significantly in group B (P < 0.05). The total efficiency rates one year after surgery in group A and group B were 68.9 and 86.7%, respectively. The total efficiency rate of group B was statistically higher than that of group A (P < 0.05).

Conclusion

PRF relieved TPHN, and gasserian ganglion PRF was more effective than peripheral nerve PRF. The method was effective and improved the quality of life of the patients. PRF is recommended as a treatment for TPHN.

Regional Nerve Blocks for Equine Dentistry

Regional nerve blocks are necessary to facilitate equine oral surgery in the standing sedated patient. Step-by-step instruction on how to perform common regional nerve blocks are discussed, including infraorbital, maxillary, middle mental, and inferior alveolar nerve blocks. Regional nerve blocks are critical when performing dental procedures in the standing horse.¹ The infraorbital and maxillary nerve blocks provide anesthesia of the infraorbital nerve, which is a branch of the maxillary nerve. Both nerve blocks provide adequate anesthesia for all maxillary dental procedures.¹ When the infraorbital nerve block is utilized, care must be taken to advance the needle into the infraorbital foramen in order to appropriately anesthetize the caudal maxillary teeth. Mandibular dental procedures require anesthesia of the inferior alveolar nerve, which is a branch of the mandibular nerve. Local anesthesia at the level of the mental foramen will result in anesthesia of ipsilateral incisors and canines, while anesthesia at the level of the mandibular foramen will anesthetize the entire ipsilateral mandibular dental quadrant. All nerve blocks should have the injection site aseptically prepared prior to the procedure. The 4 most common dental nerve blocks are described step by step.

The expression of voltage-gated sodium channels in trigeminal nerve following chronic constriction injury in rats

Objectives: Despite the etiology of trigeminal neuralgia has been verified by microvascular decompression as vascular compression of the trigeminal root, very few researches concerning its underlying pathogenesis has been reported in the literature. The present study focused on those voltage-gated sodium channels, which are the structural basis for generation of ectopic action potentials. Methods: The trigeminal neuralgia modeling was obtained with infraorbital nerve chronic constriction injury (ION-CCI) in rats. Two weeks postoperatively, the infraorbital nerve (TN), the trigeminal ganglion (TG), and the brain stem (BS) were removed and analyzed with a series of molecular biological techniques. Results: Western blot depicted a significant up-regulation of Nav1.3 in TN and TG but not in BS, while none of the other isoforms (Nav1.6, Nav1.7, Nav1.8, or Nav1.9) presented a statistical change. The Nav1.3 from ION-CCI group was quantified as 2.5-fold and 1.7-fold than that from sham group in TN and TG, respectively (p < .05). Immunocytochemistry showed the Nav1.3-IR from ION-CCI group accounted for 21.2 ± 2.3% versus 6.1 ± 1.2% from sham group in TN, while the Nav1.3-positive neurons from ION-CCI group accounted for 34.1 ± 3.5% versus 11.2 ± 1.8% from sham group in TG. Immunohistochemical labeling showed the Nav1.3 was co-localized with CGRP and IB4 but not with GFAP or NF-200 in TG. Conclusion: ION-CCI may give rise to an up-regulation of Nav1.3 in trigeminal nerve as well as in C-type neurons at the trigeminal ganglion. It implied that the ectopic action potential may generate from both the compressed site of the trigeminal nerve and the ganglion rather than from the trigeminal nuclei.

Sustained relief of trigeminal neuropathic pain by a blood-brain barrier penetrable PPAR gamma agonist

The blood–brain barrier (BBB) and blood–nerve barrier ensure protection of the nervous system but pose a challenge for the treatment of pain since it restricts passage of many therapeutic drugs. Although it is unknown which blood–neural barrier is more relevant, or whether permeabilities are the same for different barriers, we proposed that the inefficiency of thiazolidinedione-type agonists for peroxisome proliferator-activated receptor gamma (PPARɣ) is due to their difficulty in passage through the BBB. We developed a new highly BBB penetrable PPARɣ agonist for the treatment of neuropathic pain, assuming BBB permeability is a rule of thumb to estimate the overall permeability of relevant blood–neural barriers.  As an index of brain penetration, the brain–plasma ratio (Kp) of ELB00824 is 5.13, suggesting very high brain bioavailability, which is 58-fold that of pioglitazone. The series of studies presented here indicate that ELB00824 may be the most potent PPARɣ agonist currently known for acute reduction of neuropathic pain in trigeminal nerve in rat and mouse models. Low-dose PPARɣ agonist, ELB00824 (10 mg/kg), effectively decreased neuropathic hypersensitivity in mice and rats at both acute and chronic time points, a dose 100-fold lower than the effective dose (1000 mg/kg, i.p.) of pioglitazone. Comparisons of ELB00824 alone or in combination with gabapentin or carbamazepine are provided. While PPARɣ agonists used to treat Type 2 diabetes produce several adverse side effects, sub-chronic oral toxicity study provided promising results that ELB00824 does not produce any significant short-term toxicity. The study animals of either sex remained alive and healthy with no significant alteration of body weight long term. Toxicity study results obtained were satisfactory, with no significant alterations in any serum biochemistry parameters.

α2- and β2-Adrenoreceptor-Mediated Efficacy of the Atypical Antidepressant Agomelatine Combined With Gabapentin to Suppress Allodynia in Neuropathic Rats With Ligated Infraorbital or Sciatic Nerve

Previous data showed that neuropathic pain induced by mechanical lesion of peripheral nerves has specific characteristics and responds differently to alleviating drugs at cephalic versus extracephalic level. This is especially true for tricyclic antidepressants currently used for alleviating neuropathic pain in humans which are less effective against cephalic neuropathic pain. Whether this also applies to the antidepressant agomelatine, with its unique pharmacological properties as MT₁/MT₂ melatonin receptor agonist and 5-HT_2B/5-HT_2C serotonin receptor antagonist, has been investigated in two rat models of neuropathic pain. Acute treatments were performed 2 weeks after unilateral chronic constriction (ligation) injury to the sciatic nerve (CCI-SN) or the infraorbital nerve (CCI-ION), when maximal mechanical allodynia had developed in ipsilateral hindpaw or vibrissal pad, respectively, in Sprague–Dawley male rats. Although agomelatine (45 mg/kg i.p.) alone was inactive, co-treatment with gabapentin, at an essentially ineffective dose (50 mg/kg i.p.) on its own, produced marked anti-allodynic effects, especially in CCI-ION rats. In both CCI-SN and CCI-ION models, suppression of mechanical allodynia by ‘agomelatine + gabapentin’ could be partially mimicked by the combination of 5-HT_2C antagonist (SB 242084) + gabapentin, but not by melatonin or 5-HT_2B antagonist (RS 127445, LY 266097), alone or combined with gabapentin. In contrast, pretreatment by idazoxan, propranolol or the β₂ antagonist ICI 118551 markedly inhibited the anti-allodynic effect of ‘agomelatine + gabapentin’ in both CCI-SN and CCI-ION rats, whereas pretreatment by the MT₁/MT₂ receptor antagonist S22153 was inactive. Altogether these data indicate that ‘agomelatine + gabapentin’ is a potent anti-allodynic combination at both cephalic and extra-cephalic levels, whose action implicates α₂- and β₂-adrenoreceptor-mediated noradrenergic neurotransmission.

The Infraorbital Foramen Is Located Midway Between the Nasospinale and Jugale: Considerations for Infraorbital Nerve Block and Maxillofacial Surgery

Identification of the infraorbital foramen is important in infraorbital nerve block and the prevention of iatrogenic injury of the infraorbital nerve in maxillofacial surgeries. This study assessed the location of 887 infraorbital foramina from 518 adult crania of varied sex and population. The study assessed the midpoint of a line segment spanning from nasospinale to jugale (NS-J) relative to the infraorbital foramen. The mean distance of the NS-J midpoint from the infraorbital foramen was 2.1 ± 1.9 mm (mean ± SD) with a mode of 0 mm (266:887; 30%). The NS-J midpoint was located in the same plane or inferior to the infraorbital foramen in 98.4% of sides (873:887). There were no significant differences between sexes, populations, or sides with regard to the NS-J midpoint to infraorbital foramen distance. The NS-J midpoint can be used to locate the infraorbital foramen in both females and males of varied populations regardless of craniofacial diversity. The results of this study will aid in infraorbital nerve block procedures and maxillofacial surgery.

An Alternative Route for Entrapped Inferior Orbital Nerve in Orbital Floor Fracture

Orbital floor fractures pose a grave threat for injury to the infraorbital nerve, resulting in the patient suffering from a disturbing paraesthesia. It is challenging for the operating surgeon to release and secure the entrapped nerve with reconstruction of the orbital floor. We present an interesting case of orbital floor fracture with entrapped infraorbital nerve, wherein we have decompressed the nerve and provided it, a new course.

[Zygomaticomaxillary complex fractures with infraorbital nerve damage]

Zygomaticomaxillary complex (ZMC) fracture is a common type of maxillofacial fracture. In addition to facial depression and diplopia, paresthesia of the lower eyelid, malar regions, nose skin, upper lip skin, and mucous membranes occurs because of infraorbital nerve injury. This article reviewed the anatomy, diagnosis, assessment, treatment, and prognosis of ZMC fracture-related infraorbital nerve injury.

An Improved Rodent Model of Trigeminal Neuropathic Pain by Unilateral Chronic Constriction Injury of Distal Infraorbital Nerve

The number of studies on trigeminal nerve injury using animal models remains limited. A rodent model of trigeminal neuropathic pain was first developed in 1994, in which chronic constriction injury (CCI) is induced by ligation of the infraorbital nerve (IoN). This animal model has served as a major tool to study trigeminal neuropathic pain. Unfortunately, the surgical procedure in this model is complicated and far more difficult than ligation of peripheral nerves (eg, sciatic nerve). The aim of this study was to improve on the current surgical procedure of IoN ligation to induce trigeminal neuropathic pain in rats. We show that the IoN can be readily accessed through a small facial incision. CCI can be induced by ligation of a segment at the distal IoN (dIoN). This dIoN-CCI procedure is simple, minimally invasive, and time-saving. Our data show that the dIoN-CCI procedure consistently induced acute as well as chronic nociceptive behaviors in rats. Daily gabapentin treatment attenuated mechanical allodynia and reduced face-grooming episodes in dIoN-CCI rats.

PERSPECTIVE

The orofacial pain caused by trigeminal nerve damage is severe and perhaps more debilitating than other types of neuropathic pain. However, studies on trigeminal neuropathic pain remain limited. This is largely because of the lack of proper animal models because of the complexity of the existing surgical procedures required to induce trigeminal nerve injury. Our improved dIoN-CCI model is likely to make it more accessible to study the cellular and molecular mechanisms of neuropathic pain caused by trigeminal nerve damage.

Neuronal plasticity of trigeminal ganglia in mice following nerve injury

Background

Nerve injury may induce neuropathic pain. In studying the mechanisms of orofacial neuropathic pain, attention has been paid to the plastic changes that occur in the trigeminal ganglia (TGs) and nucleus in response to an injury of the trigeminal nerve branches. Previous studies have explored the impact of sciatic nerve injury on dorsal root ganglia (DRGs) and it has shown dramatic changes in the expression of multiple biomarkers. In large, the changes in biomarker expression in TGs after trigeminal nerve injury are similar to that in DRGs after sciatic nerve injury. However, important differences exist. Therefore, there is a need to study the plasticity of biomarkers in TGs after nerve injury in the context of the development of neuropathic pain-like behaviors.

Aim

The aim of this study was to investigate the plasticity of biomarkers associated with chronic persistent pain in TGs after trigeminal nerve injury.

Materials and methods

To mimic the chronic nature of the disorder, we used an intraoral procedure to access the infraorbital nerve (ION) and induced a nerve injury in mice. Immunohistochemistry and quantification were used for revealing the expression level of each biomarker in TGs after nerve injury.

Results

Two weeks after partial ION injury, immunohistochemistry results showed strongly upregulated expressions of activating transcription factor 3 and neuropeptide Y (NPY) in the ipsilateral TGs. Microglial cells were also activated after nerve injury. In regard to positive neuronal profile counting, however, no significant difference in expression was observed in galanin, substance P, calcitonin gene-related peptide, neuronal nitric oxide synthase, phosphorylated AKT, or P2X3 in ipsilateral TGs when compared to contralateral TGs.

Conclusion

In this study, the expression and regulation of biomarkers in TGs have been observed in response to trigeminal nerve injury. Our results suggest that NPY and Iba1 might play crucial roles in the pathogenesis of orofacial neuropathic pain following this type of injury. Further investigations on the relevance of these changes may help to target suitable treatment possibilities for trigeminal neuralgia.

Infraorbital Nerve Decompression for Infraorbital Neuralgia/Causalgia following Blowout Orbital Fractures: A Case Series

The purpose of this study was to present the management of a series of patients referred with infraorbital nerve paraesthesia that developed after insignificant orbital floor fracture without diplopia or exophthalmos, and that did not require initial surgical repair. This is a retrospective interventional case series. The main outcome and measures were assessment of preoperative symptoms including neuralgia and sensory symptoms; review of periorbital computed tomography (CT) scans; and assessment of postoperative effects of surgery for infraorbital nerve decompression. Nine patients were identified who developed neuralgia affecting the infraorbital nerve distribution from a cohort of 79 patients who presented with orbital floor fracture. Six were female and three were male. Age range was 22 to 73 years with a mean of 48 years. Six patients were clinically depressed due to the chronic pain. In addition, two patients had dizziness on upgaze; one patient had blurring of central vision on eye movements; and one patient had mood swings. Reviews of CT scans revealed subtle disruption of the infraorbital canal in all cases. All nine patients underwent infraorbital nerve decompression. Abnormal adhesions between the nerve and its bony canal were found in five of nine cases. Follow-up ranged from 3 to 37 months (mean: 18 months). Following surgery, after a variable period of time ranging from 1 day to 3 months, all patients had resolution of their symptoms. Mean follow-up was 18 months. Reconstructive surgeons should be aware that infraorbital nerve neuralgia, secondary to disruption of the nerve in the distorted bony canal, may be another indication for surgical intervention following orbital floor trauma in selected cases, in addition to more traditionally accepted indications. Neuralgia and causalgia are probably more common than previously thought and symptoms should be actively sought in the patient's history or else risk being overlooked and inappropriately managed. Long-term follow-up of such patients is unlikely to be practical. Patient and/or family practitioner education of possible sequelae may be one possible solution to detect this type of problem early. Nerve decompression, where indicated, may improve the patient's neuralgia and associated behavioral changes and quality of life. An optimal diagnostic and management algorithm is yet to be established.

Infraorbital nerve transposition to expand the endoscopic transnasal maxillectomy

BACKGROUND

The infraorbital nerve (ION) is a terminal branch of the maxillary nerve (V2) providing sensory innervation to the malar skin. It is sometimes necessary to sacrifice the ION and its branches to obtain adequate maxillary sinus exposure for radical resection of sinonasal tumors. Consequently, patients suffer temporary or permanent paresthesia, hypoestesthia, and neuralgia of the face. We describe an innovative technique used for preservation of the ION while removing the anterior, superior, and lateral walls of the maxillary sinus through a medial endoscopic transnasal maxillectomy.

METHODS

All patients who underwent transnasal endoscopic maxillectomy with ION transposition in our institute were retrospectively reviewed.

RESULTS

Two patients were identified who had been treated for sinonasal cancers using this approach. No major complications were observed. Transient loss of ION function was observed with complete recovery of skin sensory perception within 6 months of surgery. One patient referred to a mild permanent anesthesia of the upper incisors. No diplopia or enophthalmos were encountered in any of the patients.

CONCLUSION

The ION transposition is useful for selected cases of benign and malignant sinonasal tumors that do not infiltrate the ION itself but involve the surrounding portion of the maxillary sinus. Anatomic preservation of the ION seems to be beneficial to the postoperative quality of life of such patients.

[The CT observation and clinical significance of pneumatization of the anterior maxillary sinus]

Objective:To discuss the clinical significance of the pneumatization of the maxillary sinus by sinus CT.Method:One hundred patients encountered in our hospital during March 2012 and December 2012 were included in this study.The pneumatization of the anterior part of the maxillary sinus were observed.Result:①The pneumatization of prelacrimal recess was divided into 3 types. TypeⅠ: The pneumatization of maxillary sinus frontal process did not reach into the front of the nasolacrimal duct(42% of the left, 42% of the right); Type Ⅱ: The pneumatization of maxillary sinus frontal process extended into the front of the nasolacrimal duct,but not exceeding ½of the nasolacrimal duct circumference(39% of the left,37% of the right); Type Ⅲ: The pneumatization of maxillary sinus frontal process extended into the front of the nasolacrimal duct more than ½ of the circumference(19% of the left, 21% of the right).②The pneumatization of maxillary sinus palatal process was divided into 3 types. TypeⅠ: maxillary sinus palatal process non gasified (49% of the left, 53% of the right); Type Ⅱ: palatal process gasification into the nasal floor, but not more than ½of the width of nasal floor(45% of the left and 43% of the right);Type Ⅲ: palatal process gasification into the nasal floor more than ½ of the width of nasal floor(6% of the left, 4% of the right).③The pneumatization of maxillary sinus extended into alveolar process was divided into 3 types.Type Ⅰ: the bottom of the maxillary sinus is higher than the oral surface of hard palate(49% of the left and 51% of the right); Type Ⅱ: the bottom of the maxillary sinus is lower than the oral surface of hard palate and non tooth root protruding into the maxillary sinus(44% of the left and 39% of the right); Type Ⅲ: the tooth root process was protruded into maxillary sinus(7% of the left and 11% of the right).④The pneumatization of maxillary sinus extended into the zygomatic process was divided into 3 types. Type Ⅰ: the gasification of the zygomatic process is not more than the orbital lateral wall(80% of the left, 82% of the right); Type Ⅱ: the gasification of the zygomatic process is more than the orbital lateral wall, (20% of the left, right 18% of the right);Type Ⅲ: the gasification of the zygomatic process is also more than the inferior orbital wall, this paper is not observed Ⅲ type pneumatization.⑤The pneumatization of of the anterior wall of the maxillary sinus was divided into 3 types. Type Ⅰ: infraorbital nerve tube completely in the bone wall of the maxillary sinus(51% of the left, 57% of the right); Type Ⅱ: the half of the infraorbital neural tube was inburst into the maxillary sinus(39% of the left and 31% of the right); Type Ⅲ: infraorbital neural tube was totally protruding into to the cavity of the maxillary sinus(10% of the left and 12% of the right). Conclusion:The pneumatization of the anterior part of the maxillary sinus varies considerably and requires attention during ESS. The pneumatization degree of maxillary sinus should be confirmed accurately in preparation. It is foundamental for selecting the suitable surgical approach for Nasal endoscopic maxillary sinus surgery. It is also important for completely removed the maxillary lesions in operation.

Injured Anterior Superior Alveolar Nerve Endoscopically Resected within Maxillary Sinus

Posttraumatic facial pain is due to an injured nerve, most often a branch of the trigeminal nerve. While surgical approaches to injuries of the supraorbital, supratrochlear, infraorbital, and inferior alveolar nerves have been reported, an injury to the anterior superior alveolar nerve (ASAN) has not been reported. An algorithm is proposed for the diagnosis of injury to the ASAN versus the infraorbital nerve itself. A case is reported in which pain relief was achieved by dividing the ASAN within the maxillary sinus, leaving the proximal end exposed within the sinus at the level of the orbital floor.

Infraorbital Neuralgia Attributed to a Foreign Body

We reported a case of secondary infraorbital neuralgia due to a foreign body involving the nasal ala. As it was a very rare care, we reviewed reported literatures. This case highlights that infraorbital neuralgia could be caused by any tiny problems such as foreign body involving the area innervated by infraorbital nerve.

Does the primate pattern hold up? Testing the functional significance of infraorbital foramen size variation among marsupials

OBJECTIVES

The relative size of the infraorbital foramen (IOF) has been used to infer the ecology of extinct primates for several decades. Primates have relatively smaller IOFs than most other mammals, which may result from the fact that they pre-process and manipulate food with their hands rather than their muzzles. In primates, relative IOF area co-varies with diet, where insectivores and folivores have relatively smaller IOFs than frugivores. We wanted to determine whether the observed patterns associated with IOF variation hold across other orders.

MATERIALS AND METHODS

We examined how relative IOF area differs among marsupials occupying different ecological niches. Marsupials were chosen because they converge with primates in both ecology and morphology, but unlike primates, some marsupials approach and pre-process foods only with their muzzles. We measured IOF area and cranial lengths from 72 marsupial species, and behavioral feeding data were obtained from a subset of this sample (N = 20).

RESULTS

Relative IOF area did not vary significantly between substrate preferences. However, relative IOF area differed significantly by diet category (P < 0.001). Species that specialize in feeding on non-grassy leaves have significantly smaller relative IOF areas than species which primarily feed on grasses, insects, vertebrates, or some combination thereof. Behavioral analyses support that folivorous marsupials approach and remove food with the hands more often than marsupials from other dietary groups.

DISCUSSION

Results suggest that relatively small IOF area may reflect increased reliance on the hands while feeding, and that relative IOF size can be used as an indicator of feeding behavior.

Endoscopic-assisted infraorbital nerve release

Endoscopic-assisted techniques in plastic and craniofacial surgeries are limited. We present a patient with infraorbital nerve entrapment following traumatic facial injury that failed conservative management. Compression of the nerve was treated with an endoscopic-assisted nerve release of the surrounding soft tissue with a circumferential foraminal osteotomy.

Anatomical study of critical features on the posterior wall of the maxillary sinus: clinical implications

OBJECTIVES/HYPOTHESIS

Endonasal approaches to the pterygopalatine fossa for epistaxis or as part of a transpterygoid approach have been popularized somewhat by the ability to control the terminal branches of the maxillary artery (MA). Surgical landmarks are useful to identify these arteries. Therefore, identification of surface features on the posterior wall of the antrum that reflect the position of deeper structures within the pterygopalatine fossa would help predict anatomical position and orientation.

STUDY DESIGN

Describe the incidence of identifiable markings on the posterior wall of the maxillary sinus and ascertain their nature.

METHODS

An anatomical study of 18 cadaveric specimens noting and recording the presence, location, and number of prominences on the posterior wall of the antrum. After removing the bony wall, structure in the pterygopalatine fossa corresponding to the surface markings was noted.

RESULTS

Two prominences were identified. Prominence (P)1 extended from the upper part of the posterior wall of the maxillary sinus to the inferior orbit and corresponded to the infraorbital nerve. P2 was located at the middle part of the posterior wall, below P1, and corresponded to the MA. P2 was located medial to a vertical "drop line" where P1 connected to the posterior wall. P1 and P2 were found in 41.7% and 22.2%, respectively, of the specimens.

CONCLUSIONS

This study defines features on the maxillary sinus posterior wall from an endoscopic perspective. These landmarks may be useful to identify the MA and its branches during surgery within the pterygopalatine fossa.

LEVEL OF EVIDENCE

N/A.

Into the septum I go, a case of bilateral ectopic infraorbital nerves: a not-to-miss preoperative sinonasal CT variant

An ectopic course of the infraorbital nerve is a very rare anatomical variant of the sinonasal anatomy that carries the risk of inadvertent nerve injury during functional endoscopic sinus surgery. We describe herein a case of bilateral ectopic course of the infraorbital nerve into a maxillary sinus septum detected on computed tomography in a patient complaining of chronic headache and facial pain.

Rat whisker movement after facial nerve lesion: evidence for autonomic contraction of skeletal muscle

Vibrissal whisking is often employed to track facial nerve regeneration in rats; however, we have observed similar degrees of whisking recovery after facial nerve transection with or without repair. We hypothesized that the source of non-facial nerve-mediated whisker movement after chronic denervation was from autonomic, cholinergic axons traveling within the infraorbital branch of the trigeminal nerve (ION). Rats underwent unilateral facial nerve transection with repair (N=7) or resection without repair (N=11). Post-operative whisking amplitude was measured weekly across 10weeks, and during intraoperative stimulation of the ION and facial nerves at ⩾18weeks. Whisking was also measured after subsequent ION transection (N=6) or pharmacologic blocking of the autonomic ganglia using hexamethonium (N=3), and after snout cooling intended to elicit a vasodilation reflex (N=3). Whisking recovered more quickly and with greater amplitude in rats that underwent facial nerve repair compared to resection (P<0.05), but individual rats overlapped in whisking amplitude across both groups. In the resected rats, non-facial-nerve-mediated whisking was elicited by electrical stimulation of the ION, temporarily diminished following hexamethonium injection, abolished by transection of the ION, and rapidly and significantly (P<0.05) increased by snout cooling. Moreover, fibrillation-related whisker movements decreased in all rats during the initial recovery period (indicative of reinnervation), but re-appeared in the resected rats after undergoing ION transection (indicative of motor denervation). Cholinergic, parasympathetic axons traveling within the ION innervate whisker pad vasculature, and immunohistochemistry for vasoactive intestinal peptide revealed these axons branching extensively over whisker pad muscles and contacting neuromuscular junctions after facial nerve resection. This study provides the first behavioral and anatomical evidence of spontaneous autonomic innervation of skeletal muscle after motor nerve lesion, which not only has implications for interpreting facial nerve reinnervation results, but also calls into question whether autonomic-mediated innervation of striated muscle occurs naturally in other forms of neuropathy.

[Infraorbital schwannoma. Case report]

BACKGROUND

Infraorbital schwannoma is a benign tumor of the peripheral nerve seath composed of Schwann cells. Usually occurs between 20 and 70 years of age, are usually asymptomatic and can cause progressive, painless proptosis during growth.

CLINICAL CASE

A 32-year-old male admitted to ophthalmologic hospital with a painless, slowly progressive mass above the left lacrimal sac. At the ophthalmologic examination the tumor had a rubbery consistency and was firmly attached to the surrounding structures. The transillumination was negative. The B mode ultrasound disclosed a phakic eye as well as an infraorbital well-circumscribed homogeneous mass with a largest diameter of 19.7 mm, without involvement of the lacrimal pathway. The A mode ultrasound showed medium-high reflectivity with small internal vascularity. The computed tomography showed a homogeneous wellcircumscribed solid mass anterior and inferior to the left globe without bony erosion. Through subdermic incision the mass was excised. The histopathological diagnosis was "Infraorbital schwannoma".

CONCLUSIONS

The schwannoma is a rare benign tumor in the orbit, few cases have been reported. The definitive diagnosis is made by histopathologic findings as the presence of a true capsule, hyper-and hypocellular areas, thickening and hyalinization of the vessel walls. When these findings are not be confused with benign fusocellular tumors. We report a new case of infraorbital schwannoma and compared it with those cases previously reported.

Endoscopic endonasal approach to the infraorbital nerve with nasolacrimal duct preservation

Objectives Infraorbital nerve (ION) decompression, excision to remove intrinsic tumors, and resection with oncological margins in malignancies with perineural invasion or dissemination are usually accomplished with an open approach. The objective is to describe the surgical anatomy, technique, and indications of the endonasal endoscopic approach (EEA) to the ION with nasolacrimal duct preservation. Design Eleven sides of formalin-fixed specimens were dissected. An anterior maxillary antrostomy was performed. The length of the ION prominence within the sinus and anatomic features of the covering bone were studied. A 45-degree endoscope visualized the infraorbital prominence endonasally. An angled dissector and dural blade allowed for dissection and resection of the ION ipsilaterally and contralaterally. Results The bone features of the ION prominence allowed for ipsilateral dissection in 10 out of 11 sides. In one case with the ION surrounded by thick cortical bone, the dissection could only be started by drilling contralaterally. The 45-degree endoscope visualized 92.2% and 100% of the length of the nerve using the ipsilateral and contralateral nostrils, respectively. Ipsilaterally, 83% of its length was resected, and 96.3% was resected contralaterally. Conclusion The ION can be approached using an ipsilateral EEA with nasolacrimal duct preservation in most cases. The contralateral approach provides a wider angle to access the ION. This technique is primarily indicated in cases where the EEA can be used for tumor resection and oncological margins within the ION.

Ultrasound-guided infraorbital nerve pulsed radiofrequency treatment for intractable postherpetic neuralgia - a case report -

A 60-year-old man presented with pain on the left cheek and lateral nose. The patient had been diagnosed with facial herpes zoster in the left V2 area 6 months previously. Medical treatment was prescribed for 6 months but it had little effect. We blocked the left infraorbital nerve under ultrasound guidance, but pain relief was short term. Therefore, we performed pulsed radiofrequency treatment on the left infraorbital nerve under ultrasound guidance. Six months after the procedure, the reduction of pain was still maintained, and there was no need for further management.

Directional specificity and patterning of sensory axons in trigeminal ganglion-whisker pad cocultures

In the rodent trigeminal pathway, trigeminal axons invade the developing whisker pad from a caudal to rostral direction. We investigated directional specificity of embryonic day (E) 15 rat trigeminal axons within this peripheral target field using explant cocultures. E15 trigeminal axons readily grow into the same age whisker pad explants and form follicle-related patterns along a caudal to rostral direction. They also can grow into this target from its lateral aspects. In contrast, they are unable to invade the whisker pad from the rostral (nasal) pole. We did not find any correlation between the distribution of extracellular matrix molecules and trigeminal axon growth preferences. We also examined age-related changes in trigeminal axon responsiveness to directional cues. E19 trigeminal axons readily grew into E15 whisker pad explants from either the caudal or the rostral pole. These results suggest the presence of growth permissive and repulsive cues that guide sensory axons in the whisker pad. Furthermore, trigeminal axons lose their responsiveness to growth inhibitory cues at later stages of development.