Perineural Injection of the Ethmoidal Nerve of Horses.

OBJECTIVE: To describe the anatomical location of the ethmoidal nerve in the equine periorbital region and to determine the accuracy of a technique used to deposit local anesthetic solution adjacent to the nerve. STUDY DESIGN: Prospective experimental study. ANIMALS: Adult equine cadaver heads (n=6 for preliminary dissection; n=15 [30 nerve sites] for evaluation of injection technique). METHODS: Preliminary dissections were performed to identify landmarks for injection of local anesthetic adjacent to the ethmoidal nerve. For evaluation of the injection technique a 20 gauge 6 cm spinal needle was inserted into the rostromedial aspect of the supraorbital fossa, where the caudal aspect of the zygomatic process emerges from the frontal bone caudal and medial to the globe. The needle was inserted to its hub at an angle of 110° to the long axis of the head using a protractor, in both a sagittal plane and a transverse plane, and 0.5 mL of new methylene blue dye was injected as a marker. The ethmoidal nerve was identified by dissection immediately after each injection and inspected for proximity of the dye. RESULTS: Dye was observed surrounding the nerve in 27 of 30 sites (90%) or lying within 5 mm of the nerve at the other 3 sites. CONCLUSION: The described technique of perineural injection of the ethmoidal nerve proved reliable and simple. Anesthetizing the ethmoidal nerve may be helpful in desensitizing portions of the ipsilateral paranasal sinuses and nasal cavity innervated by the nerve when sinonasal surgery is performed in the standing horse.

Anatomy of anterior ethmoidal foramen, medial canthal tendon, and lacrimal fossa for transcutaneous anterior ethmoidal nerve block in Japanese individuals.

PURPOSE: To examine the anatomical relationships of the anterior ethmoidal foramen (AEF), medial canthal tendon (MCT), and lacrimal fossa (LF) in Japanese individuals. METHODS: Thirty-eight orbits from 19 Japanese cadavers (7 men and 12 women; average age at death, 89.3 years) were used in this experimental anatomical study. The AEF, MCT, and superior border of the LF were exposed. The following distances were then measured: 1) from the point at the medial orbital rim directly anterior to the AEF to the superior border of the MCT (AEF-MCT), and 2) from the superior border of the LF to the superior border of the MCT (LF-MCT). RESULTS: (AEF-MCT) and (LF-MCT) distances were 9.40±1.92 (mean±standard deviation) and 4.21±1.18 mm, respectively. No values of (LF-MCT) exceeded the mean (AEF-MCT) (9.40 mm). CONCLUSIONS: The transcutaneous anterior ethmoidal nerve block can be reliably performed without injury to the lacrimal sac by inserting a needle approximately 9 mm superior to the superior border of the MCT.

Decreased postoperative pain after reduction of fractured nasal bones using a nerve block of the anterior ethmoidal nerve.

There is consensus that all patients should experience minimal pain following reduction of a fractured nasal bone. The issue requiring further study is what technique will provide patients with the greatest pain relief following the reduction of nasal fractures. This study investigated the use of an anterior ethmoidal nerve block as preemptive analgesia for the management of postoperative pain associated with reduction of nasal bone fractures. The medical documents of 85 patients were reviewed for a retrospective case-controlled comparative study. Patients in the nerve block group (n=45) were injected with 2% lidocaine containing epinephrine into the anterior ethmoidal nerve and dorsal periosteum, and those in the control group (n=40) were not. The rate of patients requiring postoperative injectable analgesics was compared between the two groups. The rate of patients who received a postoperative analgesic injection was significantly lower in the nerve block group than in the control group (P=0.034). The use of an anterior ethmoidal nerve block and dorsal periosteal injection of anaesthetic solution during reduction of fractured nasal bones under general anaesthesia resulted in the effective reduction of postoperative pain. Thus, this is regarded as a good method for enhancing patient quality of care and compliance in the reduction of fractured nasal bones.

The anterior ethmoidal nerve is necessary for the initiation of the nasopharyngeal response in the rat.

Stimulation of the nasal passages with ammonia vapors can initiate a nasopharyngeal response that resembles the diving response. This response consists of a sympathetically mediated increase in peripheral vascular resistance, parasympathetically mediated bradycardia and an apnea. The current study investigated the role of the anterior ethmoidal nerve (AEN) in the nasopharyngeal response in the rat, as it is thought that the AEN provides the main sensory innervation of the nasal passages. When both AENs were intact, nasal stimulation caused significant bradycardia, hypertension, and apnea and produced Fos label ventrally within the ipsilateral medullary dorsal horn (MDH) and paratrigeminal nucleus just caudal to the obex. This labeling presumably represents activation of second-order trigeminal neurons. When only one AEN was intact, the nasopharyngeal response was slightly attenuated, and a similar pattern of Fos labeling was only seen in the trigeminal nucleus ipsilateral to the intact AEN. The trigeminal labeling contralateral to the intact AEN was significantly reduced. When both AENs were cut, the nasopharyngeal response to nasal stimulation consisted of only a slight apnea and an increase in arterial pressure; the resultant Fos labeling within the trigeminal nucleus was significantly reduced. Cutting both AENs but not stimulating the nasal passages also produced some Fos labeling within the trigeminal nucleus. These findings suggest that a single AEN can provide sufficient afferent input to initiate the cardiorespiratory changes consistent with the nasopharyngeal response. We conclude that the AEN provides a unique afferent contribution that is capable of producing the diving response.

Surgical consideration to optic nerve protrusion according to sinus computed tomography.

OBJECTIVES: This study aimed to investigate the prevalence of optic nerve protrusion (ONP) and its clinical indicators by using sinus computed tomography (CT) scan. STUDY DESIGN: Sinus CT scans of 260 consecutive patients with chronic inflammatory sinus disease were reviewed. RESULTS: The prevalence of ONP in our study population was 28%. Nineteen percent of the optic nerves protruded into the sphenoid sinuses including indentation of the sinus wall (12%) and coursing through the sphenoid sinus (8%). In the presence of contralateral ONP and/or ipsilateral anterior clinoid process pneumatization, the chance of ONP occurrence was significantly higher (both P < 0.01). They were reliable indicators of ONP (R(2) = 0.47, P < 0.01). CONCLUSIONS: ONP is a common anatomic variation observed in patients with chronic inflammatory sinus disease. To reduce optic nerve damage in surgeries, the presence of ONP according to sinus CT scans and the intraoperative findings should be carefully evaluated. EBM RATING: C-4.

[The clinical and pathological changes following anterior-ethmoid neurotomy in treating perennial allergic rhinitis with plasma].

OBJECTIVE: To research the therapy effect of perennial allergic rhinitis (PAR) with anterior-ethmoid neurotomy, and to observe the pathological changes of SP nerve fibres. METHOD: In 46 cases (neurotomy group, NG) of PAR anterior-ethmoid neurotomy were performed, the surgery effect was evaluated according to the Chinese Hai Kou allergic rhinitis diagnosis and curative access standard (1997) and compared with 17 cases simulating operation without neurotomy (non-neurotomy group, NNG) by clinical symptoms controlled counting-scores. The substance P in nasal mucous membrane of NG was observed with immunohistochemical test, meanwhile the square of positive-stained nerve fibres on the sections were measured with a quantitative analysis method after and before operation, which also were compared with that of 14 cases patients without rhinopathy (normal controlled group, NCG). RESULT: The average score reduced from 12.93 pre-operation to 6.14 post-operation (P < 0.01) in NG, but in NNG there is no significant different before and after therapy. The squares of SP immune response (SP-IR) positive-stained fibers were significant different between pre-operation and post-operation in NG. The quantities of SP-IR positive-stained fibers in nasal mucous membrane were more in PAR patients (before operation) that that in the NCG. CONCLUSION: The anterior-ethmoid neurotomy with plasm technique is an effective and simple therapical method for treating PAR. The SP of anterior--ethmoid nerve plays an important role in the pathological mechanism of PAR.

[Microwave treatment of ethmoidal nerve under nasal endoscopy in the patients with allergic rhinitis].

OBJECTIVE: To study the effect of microwave treatment of ethmoidal nerve on allergic rhinitis. METHOD: 106 cases of allergic rhinitis patients were treated with ethmoidal nerve microwave under nasal endoscope. RESULT: It showed marked effect in 89 cases(84.0%), immprovement in 12 cases(11.3%) and failed in 5 cases (4.7%) in one year follow-up. The overall effective rate was 95.3%. CONCLUSION: This result indicated that the microwave tissue coagulation in treating allergic rhinitis unde nasal endoscope is a good method for clinical treatment.

Electrical stimulation of the anterior ethmoidal nerve produces the diving response.

Stimulation of the upper respiratory tract usually produces apnea, but it can also produce a vagally mediated bradycardia and a sympathetically mediated increase in peripheral vascular resistance. This cardiorespiratory response, often called the diving response, is usually initiated by nasal stimulation. The purpose of this research was to investigate the anterior ethmoidal nerve (AEN) that innervates the nasal mucosa of muskrats (Ondatra zibethicus). Electrical stimulation of the AEN (typically 50 Hz, 100 micros and 500 microA) produced immediate and sustained bradycardia and cessation of respiration similar to that of the diving response. Heart rate (HR) significantly decreased from 264+/-18 to 121+/-8 bpm, with a concurrent 4.2+/-0.9 s apnea, during the 5 s stimulation period. BP decreased from 97.9+/-4.8 to 91.2+/-6.4 mmHg. Using estimations from (1) cross-sectional areas of AEN trigeminal ganglion cells labeled with WGA-HRP, and (2) electron microscopic analysis of the AEN, we found that approximately 65% of the AEN is composed of unmyelinated C-fibers. In addition, 72.4% of myelinated fibers from the nerves that innervate the nasal passages were of small diameter (<6 microm, presumably Adelta fibers). Thus, the AEN of the muskrat contains a high concentration of small diameter fibers (89.8%). We conclude that electrical stimulation of small diameter fibers within the AEN of muskrats can produce the cardiovascular and respiratory responses similar to that of the diving response.

Anatomic and surgical approach to the ethmoidal nerve and parasympathetic innervation of the nasal and cerebral circulation in sheep.

OBJECTIVE: To describe an anatomic and surgical approach to the efferent parasympathetic branches of the pterygopalatine ganglia in sheep, with particular reference to the ethmoidal nerve and innervation of nasal and cerebral blood vessels. ANIMALS: 12 adult sheep used for monolateral (n = 7) or bilateral (n = 5) ethmoidal neurectomy; 2 sheep used for angiography (1 live sheep for digital subtraction angiography, 1 embalmed cadaver for injection studies); and 5 embalmed cadavers, 4 frozen specimens, and 2 dry skulls used for dissection, x-rays, and computed tomographic (CT) or magnetic resonance (MR) scans. PROCEDURE: Transverse (coronal) MR scans, transverse, sagittal, and dorsal CT scans, radiography, angiography, photographic images, and dissections of embalmed material were used to study the topographic anatomy of the temporal and pterygopalatine fossae of the head. RESULTS: Images were stored, then compared with photographs of frozen sections from the same or a similar specimen to plan a surgical approach to the ethmoidal nerve. Mono- and bilateral experimental ethmoidal neurectomies were performed, allowing characterization of a safe and reliable method. The series of pterygopalatine ganglia typical of this species was localized, dissected, and analyzed for topographic relations. CONCLUSIONS: From the results, a new approach to the efferent branches of the pterygopalatine ganglia (ethmoidal nerve) for experimental parasympathectomy of the cerebral and nasal circle is proposed. This experimental approach could be used for studies involving thermoregulation of the face, and in experimental control of blood flow in the nasal cavity and rostral part of the brain.

Does histamine stimulate trigeminal nasal afferents?

The response to histamine of nasal afferents has been studied in guinea pigs by recording the electrical activity of the whole ethmoidal nerve (EN) or that of single units. Guinea pigs were anaesthetized with urethane and breathed through a tracheostomy. Prior to intranasal instillation of histamine (1 x 10(-4)-10(-1) M), the nasal mucosa was treated with 20 microl of saline (0.9% NaCl) or HCl (pH = 2), and in some cases, H2SO4 (pH = 2). In other experiments, following HCl instillation animals were pretreated by tripelennamine (1 x 10(-2) M) and/or cimetidine (1 x 10(-2) M) in order to determine the histamine receptor type of sensory nerve endings. Whole EN activity was not stimulated even by the highest dose (1 x 10(-1) M) of histamine when the nose was pretreated with saline, but was substantially stimulated by histamine in a dose-response fashion (1 x 10(-2) M) after pretreatment with HCI or H2SO4. Pretreatment with tripelennamine and HCl prevented the effect of histamine on the afferent EN activity; but after cimetidine and HCl pretreatment histamine still had a marked stimulant effect. In the case of single unit activities, histamine with HCl pretreatment had a long-lasting stimulatory effect (110.2 +/- 26.6 sec). It is concluded that the EN in guinea pigs include histamine-sensitive fibers whose sensitivity is mediated by H1 receptors and can respond to histamine only under abnormal conditions of the nasal mucosa.

The medical nucleus of the solitary tract mediates the trigeminally evoked pressor response.

The present study examined whether the nucleus of the solitary tract (NTS) plays a role in mediating the trigeminally evoked pressor response which occurs after noxious perturbation of the nasal mucosa or electrical stimulation of the ethmoidal nerve (EN5). We recorded arterial blood pressure responses to EN5 stimulations before and after injections of the calcium channel blocker CoCl2 into the NTS. Unilateral and bilateral injections of CoCl2 into the medial NTS resulted in significant blockade (p < 0.05 and p < 0.01, respectively) of the EN5-evoked pressor responses. Recovery of the pressor responses was observed 15-25 min after the CoCl2 injections. CoCl2 injections into the caudal commissural NTS remained largely ineffective with respect to blocking the EN5-evoked pressor responses. These findings strongly suggest that the medial NTS is a crucial link for the trigeminally induced pressor response.

The Kölliker-Fuse nucleus mediates the trigeminally induced apnoea in the rat.

The present study examined whether the Kölliker-Fuse nucleus (KF) plays a role in mediating the trigeminally induced apnoea which occurs after noxious perturbation of the nasal mucosa. We stimulated the ethmoidal nerve (EN5) electrically and recorded respiratory responses before and after injections of the calcium channel blocker CoCl2 into the KF. Unilateral EN5 stimulations resulted in an apnoea or in a reduction of respiratory frequency and tidal volume. EN5 stimulations immediately after ipsilateral CoCl2 injections into the caudal KF caused only minor respiratory suppression, indicating a blockade of synaptic transmission. Recovery of the respiratory responses was observed 15-120 min after the CoCl2 injection. Our data strongly suggest that the caudal KF is an obligatory relay site for trigeminally induced apnoea.

Relationship of the optic nerve to the posterior paranasal sinuses: a CT anatomic study.

PURPOSE: To delineate the relationship between the optic nerves and the posterior paranasal sinuses using CT data. METHODS: Direct coronal sinus CT scans of 150 consecutive patients with chronic inflammatory sinus disease were reviewed by two radiologists. Axial oblique reconstructions along the course of the optic nerve were obtained for the first 100 patients. The direct relationship between the optic nerve and the posterior ethmoid and sphenoidal sinuses was recorded, as were identations into the sinus wall, course of the nerve through the sinus region, pneumatization of the anterior clinoid process, and bone dehiscence. RESULTS: The relationship of the optic nerve to the posterior paranasal sinus fell into one of four discrete categories, type 1 through type 4. All 300 nerves were intimately related to the sphenoidal sinus. A small minority (3%) were in contact with the posterior ethmoidal sinus. Only type 4 nerves had contact with the posterior ethmoid air cell. Type 1 nerves course adjacent to the sphenoid sinus without indentation of the wall (228 nerves, 76%). Type 2 nerves course adjacent to the sphenoidal sinus, causing indentation of the sinus wall (44 nerves, 15%). Type 3 nerves course through the sphenoid sinus (19 nerves, 6%). Type 4 nerves course immediately adjacent to the sphenoidal sinus and the posterior ethmoidal air cell (9 nerves, 3%). Bone dehiscence over the optic nerve was found in 24% of the nerves; 4% of the optic nerves in our study had an associated pneumatized anterior clinoid process and 77% of these had an associated dehiscence over the optic canal. CONCLUSIONS: In all our cases the course of the optic nerve was adjacent to the sphenoidal sinus. Only 3% were in contact with the posterior ethmoidal sinus. Anatomic configurations that predispose the optic nerve to injury include type 2 or 3 optic nerves, bone dehiscence over the nerve, and pneumatization of the anterior clinoid process. These configurations are common and should be routinely sought out so that devastating complications from sinus surgery can be avoided.

Responses of rat medullary dorsal horn neurons following intranasal noxious chemical stimulation: effects of stimulus intensity, duration, and interstimulus interval.

1. Most quantitative examinations of nociception are performed with thermal or mechanical stimuli. Because nociceptive processing mechanisms may depend on the modality of the stimuli, comparable studies on chemonociception are necessary. 2. We examined the activity of chemonociceptive medullary dorsal horn neurons in halothane-anesthetized rats. For controlled noxious chemical stimulation, defined CO2 pulses were applied to the nasal mucosa. The effects of stimulus intensity, duration, and interstimulus interval (ISI) were tested by performing three different CO2 stimulation protocols (see below). 3. The recorded neurons were characterized by intranasal and facial stimuli of different modalities. The cells received input from intranasal A delta- and/or C-fibers. All tested neurons also responded to other intranasally applied irritants, e.g., mustard oil. Furthermore, the units were sensitive to intranasal high-threshold mechanical stimulation and to facial mechanical stimulation. According to the properties of their facial mechanoreceptive fields, the units were classified as wide dynamic range (WDR) or nociceptive specific (NS) neurons. The majority of the cells also responded to facially applied noxious heat stimuli, so that most of the recorded neurons were found to be multimodal. Some of the neurons, in addition, had convergent input from primary afferents innervating the maxillary tooth pulps or the cornea and periorbital structures. 4. In the first stimulation protocol we presented four different CO2 concentrations (25, 50, 75, and 100%; stimulus duration 2 s). In total, each concentration was applied 10 times (2 trains of 5 stimuli). Stimulus response functions (SRFs) were computed with average responses to identical stimuli. All but 2 of the 23 tested neurons displayed enhanced responses after stimulation with increasing intensities. In general, WDR cells (n = 15) discharged more vigorously to the same CO2 concentration than NS cells (n = 8). WDR neurons discriminated more reliably between stimulus intensities in the low to moderate range (25-50% CO2) than NS cells. Both categories of neurons, however, discriminated equally well in the moderate- to high-intensity range (50-75% CO2). The discriminatory capacity of WDR and NS neurons was reduced in the highest concentration range (75-100% CO2). The proportion of NS neurons significantly discriminating between these intensities tended to be higher compared with WDR neurons when stimuli were applied with long ISIs (120 s). 5. To examine the effects of the duration of the ISI, identical test sequences were performed with ISIs of 30 and 120 s. (ABSTRACT TRUNCATED AT 400 WORDS)

Postnatal development of the anterior ethmoidal nerve in cats: unmyelinated and myelinated nerve fiber analysis.

This is the first quantitative electron microscopic study of anterior ethmoidal nerve in adult and newborn cats. The adult nerve comprises about 1,000 myelinated fibers including A delta (65%) and A beta (35%) fibers and 6,000 unmyelinated fibers. At birth, only 27% of the adult myelinated fibers complement is already present. The immaturity of the nerve is discussed in relation to that of the sneeze reflex.

Effects of ethmoidal nerve stimulation on respiration-related neurones in the dorsal medulla of the cat.

Stimulation of the nasal mucosa produces a number of respiratory reflexes the afferent limb of which is provided by the ethmoidal nerve, a branch of the trigeminal nerve. In the cat this nerve terminates within the trigeminal nucleus. It has no direct projection to brainstem respiratory centres. This study examines the response of respiratory-related neurones in the nucleus of the solitary tract (NTS) to ethmoidal stimulation. It demonstrates that these neurones show both excitatory and inhibitory responses to ethmoidal stimulation. Thus, the NTS appears to be involved in respiratory reflexes initiated by stimulation of the nasal mucosa.

Surgical approaches to the sphenoid sinus.

The sphenoid sinus can be approached through the ethmoid, nasal or septal zones of the anterior wall. Case studies, fresh/fixed cadaver material and radiologic examinations, including three-dimensional CT reconstructions, were used to define the anatomic conditions governing the safest penetration of each zone. The ethmoid zone was often associated with anatomic variations such as posterior and superior placement of ethmoid cells which dictated caution. The transnasal route was best used for isolated sphenoid disease since nasal disease caused significant bleeding. A detailed description of the vomer-ethmoid relationship outlines the advantages of using the septal zone. The actual zone used to enter the sphenoid sinus must be determined by the nature of the disease process to be treated and therefore a detailed knowledge of the normal and aberrant anatomy of each zone, as elaborated by the radiological road map, is required to prevent complication.

Post-traumatic external nasal neuralgia--an often missed cause of facial pain?

Pain about the bridge of the nose is often a diagnostic dilemma. There is an important recognizable subgroup who may, as a consequence of involvement of the external nasal nerve in nasal injury, exhibit neuralgic pain after a latent interval. Temporary relief by anaesthesia can be achieved and cure is possible by division of the anterior ethmoidal nerve. This rare cause of facial pain is presented using two illustrative cases.