Ectopic Infra Orbital Nerves: Case Series of a Dangerous Normal Variant.

Normal variations in the paranasal sinus region are well documented in literature. We present five cases of a little known normal variant, which can have serious implications for the patient as well as the operating surgeon. An ectopic infra orbital nerve canal coursing through the maxillary sinus has rarely been described in imaging literature. This may sometimes be mistaken for a simple septum in the maxillary sinus and may cause serious complications during Functional Endoscopic sinus surgery (FESS) surgeries. We describe the imaging findings and present a brief review of the previous publications on the same subject.

Protrusion of the Infraorbital Nerve into the Maxillary Sinus on CT: Prevalence, Proposed Grading Method, and Suggested Clinical Implications.

BACKGROUND AND PURPOSE: The infraorbital nerve arises from the maxillary branch of the trigeminal nerve and normally traverses the orbital floor in the infraorbital canal. Sometimes, however, the infraorbital canal protrudes into the maxillary sinus separate from the orbital floor. We systematically studied the prevalence of this variant. MATERIALS AND METHODS: We performed a retrospective review of 500 consecutive sinus CTs performed at our outpatient centers. The infraorbital nerve protruded into the maxillary sinus if the entire wall of the infraorbital canal was separate from the walls of the sinus. We recorded the length of the bony septum that attached the infraorbital canal to the wall of the maxillary sinus and noted whether the protrusion was bilateral. We also measured the distance from the inferior orbital rim where the infraorbital canal begins to protrude into the sinus. RESULTS: There was a prevalence of 10.8% for infraorbital canal protrusion into the maxillary sinus and 5.6% for bilateral protrusion. The median length of the bony septum attaching the infraorbital canal to a maxillary sinus wall, which was invariably present, was 4 mm. The median distance at which the infraorbital nerve began to protrude into the sinus was 11 mm posterior to the inferior orbital rim. CONCLUSIONS: Although this condition has been reported in only 3 patients previously, infraorbital canal protrusion into the maxillary sinus was present in >10% of our cohort. Identification of this variant on CT could help a surgeon avoid patient injury.

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.

Canalis sinuosus: a rare anatomical variation.

The infraorbital canal issues a small branch on its lateral face close to its midpoint to allow passage of the anterior superior alveolar nerve. This small canal, sometimes called the canalis sinuosus, runs forward and downward to the inferior wall of the orbit, lateral to the infraorbital canal and medially bent to the anterior wall of the maxillary sinus, passing below the infraorbital foramen. Anatomical variations in the maxilla are rarely described in the literature and, in most cases, are related to the nasopalatine canal. This article describes a rare anatomical variation of the presence of a bilateral accessory canal extending from the nasal cavity lateral wall to an accessory foramen located on the hard palate, adjacent to the maxillary lateral incisor observed in cone beam computed tomography (CBCT) images. This case is an anatomical variation of the anterior superior alveolar nerve (canalis sinuosus). Identification of individual anatomical variations, especially on CBCT, may help the surgeon to avoid injuries to nerves during implant placement.

Doubled foramen rotundum and maxillary nerve fenestration.

Even though the doubled foramen rotundum (FR) can be identified once within the literature, there are no details of the contents at that level. We present here an anatomical case demonstrating the maxillary nerve (MN) duplication at the level of an unilateral doubled FR: the accessory nervous trunk of the MN separately left the trigeminal ganglion on the outer side of the MN main trunk and coursed beneath the main trunk of the MN canal, within the sphenoidal greater wing, to join infero-medially that main trunk at the entrance in the pterygopalatine fossa. Overall, the MN appeared as fenestrated, with a thin bony plate separating the two cords of the nerve traversing the skull base. Previously undocumented, the MN duplication may interfere with various surgical exposures interfering with the foramen rotundum and may explain atypical sensory syndromes and functional impairment during skull base trauma or anesthesia.

Surgical implications of an unusual anomaly of the infraorbital nerve.

The infraorbital nerve is a direct extension of the maxillary division of the Vth cranial nerve. It typically courses anteriorly through a canal within the bone of the orbital floor. We describe an unusual anatomic variation of this canal that to our knowledge has not been previously described in the literature. This anomaly may have significant implications during surgery on the paranasal sinuses and maxillofacial skeleton. Careful preoperative assessment of the course of the infraorbital nerve is necessary to prevent iatrogenic hypoesthesia, paresthesia, or neuralgia.

Crescimento dental e reparo alveolar em animais submetidos a desnervação regional / Dental growth and wound healing in regional denervated animals

Foram feitas análises macro e microscópica da influência da desnervação regional, por alcoolização, nos processos de crescimento dental e de reparo alveolar pós-exodôntico, utilizando-se 120 ratos albinos, machos com peso corporal entre 180 e 280g, mantido em colônias de cinco animais e divididos em grupos: controle e experimental (desnervação) O crescimento dental foi medido no incisivo superior nos períodos de 1, 3, 6, 9, 15 e 21 dias pós-operatórios; o reparo alveolar foi analisado nos mesmos períodos, após a exodontia do incisivo superior. Os resultados mostram que a desnervação diminui o ritmo de crescimento dental e reduz a proliferação de fibroblastos, organização vascular, a formação da matriz orgânica e do tecido ósseo, sugerindo uma possível influência neutrófica sobre os tecidos dentais e periodontais

Is Far a Hox mutation?

The mouse First arch mutation, Far, causes a severe syndrome of craniofacial defects described previously. All of the known defects are derived from the anterior first arch, and to a very small extent, the dorsal second arch. Recently Far has been shown to be closely linked to Ulnaless on chromosome 2, and therefore in the vicinity of the Hox-4 gene cluster. This paper reports the results of several studies focused on the development origin of the most consistently expressed dominant effect caused by Far, an abnormal major bifurcation of the maxillary nerve. Nerve-stained whole-mount preparations of day 12 embryos showed that in Far mutants the maxillary nerve appears to have a central wedge missing from the normal single-stalked fan shape, and that the nerve defect in Far/Far and +/Far may be equally severe. The effect of retinoic acid on the development of the maxillary nerve was tested. Maternal treatment with 5 mg/kg retinoic acid on day 9 of gestation had no detectable effect on the maxillary nerve of +/Far embryos, and similar treatment with a teratogenic dosage (20 mg/kg) on day 8 or 9 produced no Far-like maxillary nerve defects in genetically normal embryos. The neural crest cells that give rise to nerves and mesenchyme of the first arch originate from specific rhombomeres, discrete segments of the developing head. The rhombomeres of 15 embryos at the 14-23 somite stages, of which 75% are expected to be +/Far or Far/Far, were examined. There was no detectable defect in segmentation or morphology of the rhombomeres compared with controls. The significance of ectopic cartilage in the palate of Far/Far mutants in relation to nerve bifurcation was explored. In histological studies, five out of six Far/Far day-15 fetuses had a rod of ectopic cartilage lateral to the posterior palate, running parallel to, and morphologically similar to, Meckel's cartilage, and lying between the two trunks of the abnormally bifurcated maxillary nerve. None of six +/Far day-15 fetuses examined had detectable ectopic cartilage in this region. We hypothesize that the maxillary nerve defects in Far mutants may be explained by the presence of an ectopic precartilaginous blastema that does not always further develop into detectable cartilage. The ectopic cartilage found in Far/Far resembles the epibranchial cartilage expressed in more posterior branchial arches and in the first arch of lower organisms, and therefore may represent an atavistic posteriorization of the anterior first arch in Far mutants.(ABSTRACT TRUNCATED AT 400 WORDS)

Hemifacial deficiency induced by a shift in dominance of the mouse mutation far: a possible genetic model for hemifacial microsomia.

Hemifacial deficiency appeared in 10% of juvenile mice when BALB/cGaBc mice carrying the recessive lethal mutation far were crossed with ICR/Bc. The hemifacial deficiency increased to 15-20% after one backcross to ICR/Bc and then remained at that level for 11 additional generations of backcrossing of far into ICR/Bc. Neither the ICR/Bc strain nor BALB/cGaBc (+/far) produces hemifacial deficiency. Genetic and anatomical studies of adults and fetuses showed that the hemifacial deficiency was due to +/far in the ICR/Bc strain genome; that is, far becomes an incomplete dominant in the ICR/Bc strain background. The hemifacial deficiency (38% of +/far) is probably caused by premature synostosis of the maxilla and premaxilla, observable on day 16 of gestation. An additional 20% of +/far in ICR/Bc have cleft palate and die at birth. Most +/far in both strains have a hidden anomaly, bilateral splitting of the maxillary branch of the trigeminal nerve. far/far homozygotes of both strain backgrounds have a syndrome of severe bilateral deficiency of the derivatives of the maxillary prominence. In human pedigrees, where the equivalents of the dominance modifiers in BALB/cGaBc and ICR/Bc would segregate within families, it would be difficult to recognize that sporadic hemifacial deficiency and severe bilateral maxillary deficiency were due to the same gene. We suggest that human bilateral and unilateral abnormalities of tissue derived from the first branchial arch should be analyzed with the awareness that, in mice, at least, the two kinds of syndrome are due to the same mutant gene.