Canalis sinuosus: anatomical variation or structure?

PURPOSE: The main goal of the present study was to verify the presence, spatial location, the end of the canalis sinuosus (CS) trajectory and size of CS using cone beam computed tomography (CBCT) to characterise it as either a structure or an anatomical variation. METHODS: A trained examiner specialist in dental radiology and imagenology selected 200 CBCT images of the maxilla from 107 (53.5%) female and 93 (46.5%) male individuals aged between 18 and 85 years. RESULTS: A total of 133 (66.5%) patients had CS, being 61 (45.86%) unilateral and 72 (54.14%) bilateral. A higher frequency of CS was observed in males (P < 0.05) and no relationship was found between its presence and age. The end of the CS trajectory was more frequent in the regions of central incisor (n = 91; 44.39%), followed by lateral incisor (n = 45; 21.95%) and canine (n = 29; 14.15%). In our sample, the majority of these canals had a diameter of up to 1 mm (n = 198/205; 96.6%). No statistically significant relationship between diameter and the end of the CS trajectory, with location (i.e. bilateral or unilateral) was found. Gender and age had no influence on diameter, spatial location and the end of the CS trajectory (P > 0.05%). CONCLUSION: As CS was frequently found in our sample, it can be considered an anatomical structure, and as such, it is fundamental that the dentist requests a CBCT examination before performing any invasive procedure in the maxillary region to preserve this important structure.

The maxillary nerve block for in-office hybrid balloon sinus dilation procedures: A preliminary study.

Transitioning of rhinologic procedures from the operating room to the office setting in selected patients is a rising trend. An effective pain-control, patient-preparation protocol is essential, especially with advanced in-office rhinologic procedures such as hybrid balloon sinus dilation (BSD), in which other procedures such as ethmoidectomy, turbinate reduction, and other procedures are concomitantly performed. A regimen using oral sedation, topical tetracaine gel, topical tetracaine/epinephrine-soaked cottonoid packs, and intranasal local infiltrative anesthesia can vary significantly in effectiveness and be suboptimal at times (as determined by using treated patients as historical controls). A modification of this regimen was subsequently used, incorporating the maxillary nerve block, and qualitative differences were then assessed retrospectively between the two regimens. Twenty-five consecutive patients were retrospectively studied who underwent hybrid BSD procedures in the office setting using the maxillary nerve-block regimen modification. All patients underwent BSD of the sphenoid, frontal, and maxillary sinuses with anterior and partial posterior ethmoidectomies. Five patients also underwent septoplasty, and 18 patients underwent inferior turbinate reduction procedures. Twenty-four patients received oral sedation, and all patients received topical tetracaine/epinephrine-soaked cottonoid packs. The topical tetracaine gel was dropped after 5 patients because it was not felt to be needed anymore. No intranasal local infiltrative anesthesia was used. Several qualitative differences were observed after modifying the patient-preparation regimen incorporating the maxillary nerve block. The most important observation seen with this modification was a consistently reproducible, dense anesthesia coverage over the entire nasal cavity with good paranasal sinus coverage. This modification eliminated intranasal bleeding and swelling associated with intranasal local anesthetic injections. No complications were encountered. This preliminary study provides support for use and further evaluation of the maxillary nerve block for in-office rhinologic procedures. If the trend continues to rise in performing advanced in-office rhinologic procedures in selected patients, the maxillary nerve block may find a place in the patient-preparation protocol.

Anterior superior alveolar nerve injury after extended endoscopic medial maxillectomy: a preclinical study to predict neurological morbidity.

BACKGROUND: Endoscopic medial maxillectomies (EMMs) are used to optimize exposure of the maxillary sinus and retromaxillary areas. Although in type D EMM (Sturmann-Canfield procedure) the anterior superior alveolar nerve (ASAN) is always at risk of injury, only 29% of patients complained of alveolar process and dental anesthesia. The purpose of this anatomical study is to assess the neural anastomotic network of the ASAN (ASAN-NAN) and describe different extensions of type D EMMs in a preclinical setting. METHODS: The ASAN and its medial anastomotic branches (MABs) and lateral anastomotic branches (LABs) were evaluated by cone-beam computerized tomography (CBCT). Five different extensions of type D (D1 to D5) EMMs were identified and nerves at risk of injury in each type were assessed by CBCT. Moreover, quantification of surgical corridors was performed on cadaver heads with a neuronavigation system. RESULTS: Fifty-seven CBCT scans were analyzed. The ASAN would be spared in 16.3% of cases with a type D1 EMM, while it would be injured in the majority of type D2 to D5 resections. At least 1 nerve of the ASAN-NAN was spared in 96.6%, 93%, 74.6%, 0%, and 65.8% of type D1 to D5 EMMs, respectively. Two cadaver heads were dissected and the incremental volume and number of maxillary subsites exposed was assessed in type D1 to D5 EMMs. CONCLUSION: ASAN function impairment is probably compensated by LABs and MABs. If this hypothesis will be validated in a prospective study on patients, preoperative CBCT evaluation could predict neurological morbidity after type D EMM, and allow tailoring the procedure to minimize impairment of the ASAN-NAN.

Enlargement of the infraorbital canal following Caldwell-Luc surgery.

OBJECTIVES: The infraorbital canal (IOC), which runs in the roof of the maxillary sinus, is a useful anatomical landmark for the infraorbital nerve (ION) on computed tomography (CT) images. Enlargement of the IOC on CT images is thought to be a pathological state that usually affects the ION. However, we have frequently observed enlargement of the IOC in patients with a history of radical surgery of the maxillary sinus: so-called Caldwell-Luc (CL) surgery. In this study, the size of the IOC of the maxillary sinus was compared between patients with a history of CL surgery (post-CL IOCs) and those with no history of CL surgery (control IOCs). METHODS: A total of 347 consecutive patients who underwent facial CT from January 2014 to October 2014 for various indications were evaluated. After excluding groove-type IOCs and IOCs with pathological lesions that could affect their diameters, 47 post-CL IOCs in 26 patients were finally compared with 504 control IOCs in 252 patients. To evaluate IOC size, the short-axis diameter of the IOC was measured on a reconstructed coronal image at the level of the posterior pole of the eyeball. RESULTS: The short-axis diameters of the post-CL IOCs and control IOCs were 3.0 ± 0.6 and 1.4 ± 0.3 mm, respectively (p < 0.005). CONCLUSIONS: The short-axis diameters of post-CL IOCs are significantly enlarged (approximately double the diameter) compared to those of control IOCs.

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.

Infraorbital canal bilaterally replaced by a lateroantral canal.

The infraorbital canal (IOC) normally courses above the maxillary sinus in the orbit floor. During a retrospective study of cone beam computed tomography (CBCT) scans, we found a previously unknown variant of the IOC. The IOCs were absent, being replaced by lateroantral canals coursing around and not above the maxillary sinus to open at infraorbital foramina which were located above the second upper premolar teeth. On coronal multiplanar reconstructions, the lateroantral canals were located anatomically at the outer limit of the zygomatic recess of each maxillary sinus, while the upper wall of the sinus was devoid of any canal. Such rare variant should be kept in mind by dental practitioners and surgeons, as it can determine modifications of common procedures. In this regard, the anatomy of maxilla, as well as mandible, should be evaluated in CBCT on a case-by-case basis.

[Variant anatomy of maxillar sinus according to the data of computer tomography with 3D function].

The paper presents the data on variant and individual anatomy of the maxillary sinus in 400 men and women of the I and II periods of adulthood obtained using by computer tomography with 3D function. It was found that in the I period of adulthood, 12.5% of individuals had the bony septa in the alveolar recess of the maxillary sinus which were oriented frontally--Underwood's septa. Individuals of the II period of adulthood had this septa in 20% of cases. Also in the second age group, 7.2% of the cases demonstrated the septa which are oriented sagittally. These structures were often associated with the bony canal of the infraorbital nerve. The detected variants of individual variability of the maxillary sinus have both theoretical and practical importance. In particular, during the planning of micromaxillotomy (through the endonasal access or fossa canina), the presence of bone septa, their location and the course of the infraorbital nerve canal should be taken into account.

[The treatment of trigeminal neuralgia by resecting maxillary nerve and infraorbital nerve under the endoscopy at the pterygopalatofossa through approach to the maxillary sinus].

OBJECTIVE: This paper presents a method for treating maxillary neuralgia, the second division of trigeminal nerve. METHOD: One hundred and thirty six cases with 136 trigeminal neuralgia were treated from 2004 to 2011. All patients were treated with endoscopic surgery at the pterygopalatofossa through approach to the maxillary sinus for resecting maxillary nerve and infraorbital nerve. RESULT: One hundred and eighteen patients were relieved after operation and no recurrence of neuralgia was occurred after 2 to 8 years of follow-up. CONCLUSION: This method had the advantages of avoiding to operate craniotomy with no complications, which was performed easily with valid efficacy.

Pterygopalatine fossa segment neurectomy of maxillary nerve through maxillary sinus route in treating trigeminal neuralgia.

PURPOSE: To explore an effective surgical treatment for pain in the distribution area of the maxillary branch of trigeminal nerve (TN). MATERIALS AND METHODS: Twenty-six patients with pain in the distribution of the maxillary branch of TN were followed up after they had undergone pterygopalatine fossa segment neurectomy of maxillary nerve through maxillary sinus route. RESULTS: In all cases, the pain initially resolved after operation, with anaesthesia or paraesthesia in the operated side of the maxillary nerve-distributed area. After a mean follow-up period of 24 (range 3-36) months, 19 (73.08%) of the 26 patients had an excellent response, 5 (19.23%) had a good response, 2 (7.69%) had a fair response, and none (0%) had a poor response. One patient had a recurrence with palatal pain 3 months after the operation. CONCLUSIONS: The maxillary sinus route can provide a clear vision for sectioning of the maxillary nerve. This new surgical technique has proven to be safe and effective. It provides another option for the weak elderly who are intolerant of craniotomy or patients who have contraindications for craniotomy when radiofrequency thermocoagulation (RFT) and percutaneous glycerol neurolysis (PGR) treatment is not possible.

The transmaxillary endoscopic approach to the orbit.

OBJECTIVE: In this surgical-anatomical cadaveric study we investigate the feasibility of the transmaxillary endoscopic approach to the intraorbital space. Anatomical landmarks are defined, the endoscopic view in the orbital space is studied and complications that can occur are discussed. METHODS: Nine formalin-fixed heads were used to study the transmaxillary endoscopic approach to the orbit. The approach was used twice on each head (once for each maxilla). Therefore, we report our results on 18 transmaxillary intraorbital approaches. For better differentiation of anatomical structures, the veins and arteries were injected with blue and red plastic respectively in six cadaveric heads. RESULTS: The transmaxillary approach enables viewing the inferior intraconal structures without endangering the infraorbital nerve and its artery and without diversion of the inferior rectus muscle. The optic nerve was visualised more easily through the approach medial to the inferior rectus muscle instead of lateral to the muscle since the ciliary nerves are in the way in the lateral approach. The combination of the approaches medial and lateral to the inferior rectus muscle allows very good identification of all important anatomical structures in the inferior intraconal space. CONCLUSION: The transmaxillary endoscopic approach to the orbit is a useful new approach in the surgical armamentarium for orbital lesions. The overview of the inferior part of the orbit is excellent, and the lateral part of the optic nerve can be visualised. Careful anatomical dissection allows visualisation of important anatomical structures in the orbit without damaging nerves or arteries.

Distributions of calcitonin gene-related peptide and substance P in the human maxillary sinus of Japanese cadavers.

BACKGROUND: Substance P (SP) and calcitonin gene-related peptide (CGRP) are released by the nociceptive sensory nerve and are involved in blood flow, pain and inflammation in the nasal mucosa. The purpose of this study was to assess the distribution of the SP and CGRP nerve fibres related to blood supply within human Schneiderian membrane of the maxillary sinus (MS). MATERIAL AND METHODS: In this study, the MS from Japanese cadavers was examined by whole-mount immunohistochemistry. Human male cadavers (ranging in age from 80 to 90 years) were used in this study. RESULTS: SP- and CGRP-positive fibres were found around large vessels of the medialis superior alveolar branches and also within the floor region of the MS. The floor region of the MS was composed of complex branches of these fibres. CONCLUSION: Our results give useful information for surgical sinus floor elevation in this region of the MS. These anatomical features may assist in the execution of a successful surgical procedure.

Observing the bony canal structure of the human maxillary sinus in Japanese cadavers using cone beam CT.

We observed the location of the posterior superior alveolar artery (PSAA) and nerve at the macroscopic level between the maxillary sinus (MS) and surrounding bone of the anterior region of the maxilla. This study was completed using cone beam computed tomography (CBCT) imaging of 19 human cadavers with 38 sides of Japanese origin (ranging in age from 59-94 years, mean 77.7 +/- 9.8 years) that were prepared for this study. The bony canal structure of the inner surface of the maxilla was clearly apparent in our results, and the bony canals were classified into three types according to the structure along the course of the PSAA: canal-like, ditch-shaped tunnel and fragmented, and the lest sides were undefined. Calcitonin gene-related peptide (CGRP)-positive fibers were identified along the PSAA in the bony canal of the maxilla by immunohistochemistry. The presence of the bony structure and CGRP-positive nerve fibers along the PSAA suggests that there is risk to the PSAA during surgery involving graft implant in the floor of the maxillary sinus.

Evaluation of the blood and nerve supply patterns in the molar region of the maxillary sinus in Japanese cadavers.

The maxillary sinus (MS) in the maxilla bone is located near the orbit, the nasal cavity and the oral cavity; however, the positioning of the constituent bones is complex. The posterior superior alveolar branches of the maxillary artery and nerve are distributed in the lateral wall of the MS. The courses of these blood vessels and nerves are restricted by the morphology of the craniofacial bones, and the landmarks used in dental implant treatment of these courses mainly run along the lateral wall of the MS. In this study, 19 human cadavers with 34 sides of Japanese origin (ranging in age from 59-94 years, mean 77.7 +/- 9.8 years) were prepared for measurement of the MS, the superior alveolar artery and the infraorbital artery using cone beam computed tomography (CBCT). The posterior superior alveolar artery (PSAA) of the lateral wall of the MS can be classified into one of three groups based on the supply pattern. In the greatest number of cadavers, the PSAA ran mainly to the lateral surface of the zone between the superior border of the alveolar foramen and the inferior border of the MS (53.0%, 18/34). In others, the PSAA ran to the zone between the infraorbital foramen and the superior border of the alveolar foramen (17.6%, 6/34); in a third group, the PSAA ran to the zone between the inferior border of the MS and the greater palatine foramen (23.5%, 8/34). The lest of two sides are spread out in this area (5.9%, 2/34). CBCT is the most accurate tool to evaluate important anatomical parameters, such as the distance of the blood supply, for the implant of grafts in the floor of the MS during surgical procedures.

Endoscopic anatomy of the pterygopalatine fossa and the transpterygoid approach: development of a surgical instruction model.

INTRODUCTION: The pterygopalatine fossa (PPF) is a narrow space located between the posterior wall of the antrum and the pterygoid plates. Surgical access to the PPF is difficult because of its protected position and its complex neurovascular anatomy. Endonasal approaches using rod lens endoscopes, however, provide better visualization of this area and are associated with less morbidity than external approaches. Our aim was to develop a simple anatomical model using cadaveric specimens injected with intravascular colored silicone to demonstrate the endoscopic anatomy of the PPF. This model could be used for surgical instruction of the transpterygoid approach. METHODS: We dissected six PPF in three cadaveric specimens prepared with intravascular injection of colored material using two different injection techniques. An endoscopic endonasal approach, including a wide nasoantral window and removal of the posterior antrum wall, provided access to the PPF. RESULTS: We produced our best anatomical model injecting colored silicone via the common carotid artery. We found that, using an endoscopic approach, a retrograde dissection of the sphenopalatine artery helped to identify the internal maxillary artery (IMA) and its branches. Neural structures were identified deeper to the vascular elements. Notable anatomical landmarks for the endoscopic surgeon are the vidian nerve and its canal that leads to the petrous portion of the internal carotid artery (ICA), and the foramen rotundum, and V2 that leads to Meckel's cave in the middle cranial fossa. These two nerves, vidian and V2, are separated by a pyramidal shaped bone and its apex marks the ICA. CONCLUSION: Our anatomical model provides the means to learn the endoscopic anatomy of the PPF and may be used for the simulation of surgical techniques. An endoscopic endonasal approach provides adequate exposure to all anatomical structures within the PPF. These structures may be used as landmarks to identify and control deeper neurovascular structures. The significance is that an anatomical model facilitates learning the surgical anatomy and the acquisition of surgical skills. A dissection superficial to the vascular structures preserves the neural elements. These nerves and their bony foramina, such as the vidian nerve and V2, are critical anatomical landmarks to identify and control the ICA at the skull base.

[Venous drainage and innervation of the maxillary sinus]. / Drainage veineux et innervation du sinus maxillaire.

The maxillary sinus, or "Highmore's antrum", is a cavity of the facial structure buried in the body of the maxillary body joined to the nasal fossae with which it communicates via the maxillary ostium. The dissection of 25 maxillary sinuses has enabled us to study its venous drainage and innervation. The venous system is collected either by a single trunk, which is a continuation of the spheno-palatine vein, or by three venous plexus: the anterior and posterior pterygoid plexus, and the alveolar plexus. The anterior and posterior pterygoid plexus converge through the lateral pterygoid muscle and connects with the alveolar plexus which drains partly into the maxillary vein and partly into the facial vein. The innervation of the maxillary sinus is ensured by the maxillary nerve (V2): the second branch of the trigeminal nerve and its collateral branches. During the course of its track the maxillary nerve becomes successively the spheno-palatine nerve and the anterior orbital nerve, and gives rise to some collateral branches: the posterior and superior alveolar ramus, the medium and superior alveolar nexus and the anterior and superior alveolar ramus.

The trigeminal nerve. Part III: The maxillary division.

The maxillary nerve gives sensory innervation to all structures in and around the maxillary bone and the midfacial region including the skin of the midfacial regions, the lower eyelid, side of nose, and upper lip; the mucous membrane of the nasopharynx, maxillary sinus, soft palate, palatine tonsil, roof of the mouth, the maxillary gingivae, and maxillary teeth. This vast and complex division of the trigeminal nerve is intimately associated with many sources of orofacial pain, often mimicking maxillary sinus and/or temporomandibular joint involvement. For those who choose to treat patients suffering with orofacial pain and temporomandibular disorders, knowledge of this nerve must be second nature. Just providing the difficult services of a general dental practice should be stimulus enough to understand this trigeminal division, but if one hopes to correctly diagnose and treat orofacial pain disorders, dedication to understanding this nerve cannot be overstated. In this, the third of a four part series of articles concerning the trigeminal nerve, the second or maxillary division will be described and discussed in detail.

Regeneration of nerve fibres in the maxillary sinus mucosa after experimental surgery. An immunocytochemical double-labelling study in the rabbit.

Nerve fibre regeneration in the maxillary sinus mucosa after surgery was studied in 10 New Zealand White rabbits. Four and 8 weeks following unilateral removal of the mucosa, the animals were fixed by perfusion, and the nose-sinus complexes were frozen and cut on a cryostat equipped with a tungsten-hardened knife. A double-labelling immunocytochemical procedure was developed with commercially available antibodies to protein gene product (PGP) 9.5 and tyrosine hydroxylase (TH) or neuropeptide Y (NPY). The study revealed that the maxillary sinus mucosa in rabbit is reinnervated at 4 and 8 weeks postoperatively. Furthermore, the regenerated lamina propria showed increased TH immunoreactivity (TH-IR) and NPY-IR, compared with the contralateral, non-operated side. Many of the fibres were seen in close proximity to newly formed vessels. These findings add further to the explanation of the altered vasoreactivity found earlier in regenerated sinus mucosa 1 month after surgery. This study also showed that demineralization of the nose-sinus complexes is not necessary if a hardened metal knife is used.

Nitric oxide is a regulator of mucociliary activity in the upper respiratory tract.

The in vitro effects of the nitric oxide (NO) substrate L-arginine on ciliary beat frequency and the in vivo effects of the NO donor sodium nitroprusside (SNP) on mucociliary activity were investigated in the rabbit maxillary sinus mucosa with photoelectric techniques. L-Arginine increased ciliary beat frequency in vitro with a maximum response of 27.1% +/- 6.4% at 10(-3) mol/L, and this effect was reversibly blocked by pretreatment with the NO synthase (NOS) inhibitor N(G)-nitro-L-arginine, whereas D-arginine had no such effect. SNP increased mucociliary activity in vivo, the peak response of 36.8% +/- 4.2% being obtained at the dose of 30.0 microg/kg. No tachyphylaxis was observed after repeat challenge with SNP. The increase in mucociliary activity caused by SNP was largely unaffected by pretreatment with the calcium channel blocker nifedipine, the cyclooxygenase inhibitor diclofenac, and the cholinergic antagonist atropine. The nonselective beta-blocker propranolol delayed the peak response of SNP to 7 to 8 minutes after challenge, compared with 1 to 2 minutes after challenge in animals without pretreatment. The results show the NO substrate L-arginine and the NO donor SNP to have ciliostimulatory effects in vitro and in vivo, respectively. The occurrence of NOS production in the sphenopalatine ganglion and sinus mucosa of the rabbit was studied by immunohistochemistry for NOS activity or nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry. The latter is an indirect sign of neuronal NOS activity. Numerous NOS-containing cell bodies were seen in the sphenopalatine ganglion; in the sinus mucosa a moderate supply of thin NOS-immunoreactive nerve fibers was seen. Taken together, the morphologic findings and the functional results indicate NO to be a regulator of mucociliary activity in upper airways.

Central projections of nerves innervating the rabbit maxillary sinus localized using wheat germ agglutinin-horseradish peroxidase or choleragenoid-horseradish peroxidase.

Central projections of nerves innervating the rabbit maxillary sinus were localized by using wheat germ agglutinin-horseradish peroxidase (WGA-HRP) or choleragenoid-horseradish peroxidase (B-HRP). Tracer was placed into the left maxillary sinus; rabbits were killed 3 or 5 days later, and histochemical localization of transported WGA-HRP or B-HRP was performed. Labeled cell bodies (437-545/animal) were seen in the ipsilateral trigeminal ganglion. Very few labeled cell bodies (zero to three/animal) were observed in the contralateral ganglion. The area of cell bodies labeled by WGA-HRP appeared similar to the area of cell bodies labeled by B-HRP. Transganglionic projections from either tracer were localized to lamina II of the ipsilateral subnucleus caudalis. In addition, WGA-HRP labeling was occasionally observed in lamina I. No labeling was present in other areas of the brainstem. In contrast to the above results, other studies have demonstrated that B-HRP produces terminal-like labeling in deeper layers of the gray matter. We injected B-HRP into the infraorbital nerve and sciatic nerve, which are known to contain projections to deep layers of the gray matter. Labeling was observed in the deep layers of the medullary or spinal dorsal horn 5 days later, suggesting that nerves innervating the sinus only project to superficial laminae. These results suggest that neurons in superficial laminae of the subnucleus caudalis may be important for the reflex initiation of the increased glandular secretions in the maxillary sinus during sinusitis.