Integrated Control of Predatory Hunting by the Central Nucleus of the Amygdala.

Superior predatory skills led to the evolutionary triumph of jawed vertebrates. However, the mechanisms by which the vertebrate brain controls predation remain largely unknown. Here, we reveal a critical role for the central nucleus of the amygdala in predatory hunting. Both optogenetic and chemogenetic stimulation of central amygdala of mice elicited predatory-like attacks upon both insect and artificial prey. Coordinated control of cervical and mandibular musculatures, which is necessary for accurately positioning lethal bites on prey, was mediated by a central amygdala projection to the reticular formation in the brainstem. In contrast, prey pursuit was mediated by projections to the midbrain periaqueductal gray matter. Targeted lesions to these two pathways separately disrupted biting attacks upon prey versus the initiation of prey pursuit. Our findings delineate a neural network that integrates distinct behavioral modules and suggest that central amygdala neurons instruct predatory hunting across jawed vertebrates.

Nationwide randomised trial evaluating elective neck dissection for early stage oral cancer (SEND study) with meta-analysis and concurrent real-world cohort.

BACKGROUND: Guidelines remain unclear over whether patients with early stage oral cancer without overt neck disease benefit from upfront elective neck dissection (END), particularly those with the smallest tumours. METHODS: We conducted a randomised trial of patients with stage T1/T2 N0 disease, who had their mouth tumour resected either with or without END. Data were also collected from a concurrent cohort of patients who had their preferred surgery. Endpoints included overall survival (OS) and disease-free survival (DFS). We conducted a meta-analysis of all six randomised trials. RESULTS: Two hundred fifty randomised and 346 observational cohort patients were studied (27 hospitals). Occult neck disease was found in 19.1% (T1) and 34.7% (T2) patients respectively. Five-year intention-to-treat hazard ratios (HR) were: OS HR = 0.71 (p = 0.18), and DFS HR = 0.66 (p = 0.04). Corresponding per-protocol results were: OS HR = 0.59 (p = 0.054), and DFS HR = 0.56 (p = 0.007). END was effective for small tumours. END patients experienced more facial/neck nerve damage; QoL was largely unaffected. The observational cohort supported the randomised findings. The meta-analysis produced HR OS 0.64 and DFS 0.54 (p < 0.001). CONCLUSION: SEND and the cumulative evidence show that within a generalisable setting oral cancer patients who have an upfront END have a lower risk of death/recurrence, even with small tumours. CLINICAL TRIAL REGISTRATION: NIHR UK Clinical Research Network database ID number: UKCRN 2069 (registered on 17/02/2006), ISCRTN number: 65018995, ClinicalTrials.gov Identifier: NCT00571883.

Topographic anatomy of the great auricular point: landmarks for its localization and classification.

PURPOSE: The great auricular point (GAP) marks the exit of the great auricular nerve at the posterior border of the sternocleidomastoid muscle (SCM). It is a key landmark for the identification of the spinal accessory nerve, and its intraoperative localization is vital to avoid neurological sequelae. This study delineates the topography and surface anatomy landmarks that used to localize the GAP. METHODS: Thirty cadaveric heminecks were dissected on a layer-by-layer approach. The topography of the GAP was examined relative to the insertion point of the SCM at the clavicle, tip of the mastoid process, and angle of the mandible. The GAP and its relation to the SCM were determined as a ratio of the total length of the SCM. RESULTS: The GAP was demonstrated to be in a predictable location. The mean length of the SCM was 131.4 ± 22 mm, and the mean distance between the GAP and the mastoid process was found to be 60.4 ± 13.76 mm. The ratio of the GAP location to the total SCM length ranged between 0.33-0.57. The mean distance between the angle of the mandible and the GAP was determined to be 57 ± 22.2 mm. Based on the midpoint of the SCM, the GAP was above it in 66.7 % of subjects and classified to Type A, and below it in 33.3 % of subjects appointed to Type B. CONCLUSIONS: The anatomical landmarks utilized in this study are helpful in predicting the location of the GAP relative to the midpoint of the SCM and can reduce neural injuries within the posterior triangle of the neck.

Reconstruction for facial nerve defects of zygomatic or marginal mandibular branches using upper buccal or cervical branches.

BACKGROUND: Many reconstructive methods for facial nerve defects have been described previously, such as the greater auricular nerve graft, the sural nerve graft, or hypoglossal-facial nerve anastomosis. Herein, we want to instruct a new technique of repairing facial nerve defects of zygomatic or marginal mandibular branches using upper buccal or cervical branches when we have to face segment defects of facial nerve with wide gaps between facial nerve stumps. METHODS: The distal part of the upper buccal or cervical branches with peripheral tissue was removed to repair the defects of zygomatic or marginal mandibular branches. Clinical and electromyographic examinations were employed to investigate the clinical efficacy of this method. RESULTS: Killed branches of facial nerve included 11 marginal mandibular branches and 16 zygomatic branches in 26 patients. The length of facial nerve defects ranged from 0.9 cm to 2.3 cm with a mean gap of 1.87 cm (SD, 0.89). Seventeen patients finally showed a superb facial function (grade I), 6 patients an excellent outcome (grade II), and 3 patients a good result (grade III). A fair or poor result (grade IV or V) was not observed. CONCLUSIONS: The essence of this method is equivalent to direct facial-facial nerve anastomosis which seems to be able to avoid synkinesis between the upper and lower face. We believe that this method is adaptable to the length of facial nerve defects less than 2 cm.

Transverse cervical and great auricular nerve distribution in the mandibular area: a study in human cadavers.

The angle of the jaw is innervated by the auricular branch of the superficial cervical plexus (SCP). Cervical cutaneous nerves of the CP carry the sensation from the antero-lateral cervical skin. It is clinically relevant to identify the cervical cutaneous nerve distribution and the nerve point using superficial landmarks but published studies describing the emerging patterns and cervical cutaneous nerve branch distributions in the mandible are rare. The overlap between the cervical and trigeminal and facial nerve distributions and anastomoses is highly variable. The objective of this study was to characterize the distribution of the SCP nerves in the different parts of the mandible. Two hundred and fifty fresh and formalin-fixed human cadaver heads were microdissected to observe the distribution of the transverse cervical (TCN) and great auricular (GAN) nerves. Two main groups (G1 and G2) based on the emergence of the TCN and GAN behind the posterior edge of the sternocleidomastoid muscle and three types (T1, T2, and T3) based on their distribution in the different mandibular parts were observed. Statistical analysis showed that parameters related to the mandibular side (P = 0.307), gender (P = 0.218), and group (P = 0.111) did not influence the facial distribution of these nerves. The only parameter influencing the distribution was the type of nerve (GAN and TCN) (P < 0.001). In the face, the SCP reached the mandible in 97% of cases, its distribution and extent were subject-dependent. These results confirmed that the SCP could supply accessory innervation to the mandible through the TCN.

Quantitative analysis of the terminal branches of facial nerve in fresh frozen head and neck specimens.

BACKGROUND: The first aim of this study was the quantification of nerve fibres found in terminal branches of facial nerve and the second aim was the ultrastructural analysis of these terminal branches in order to observe their ultrastructural differences, if present. In the examination of literature; we could not find any studies related to this subject. MATERIALS AND METHODS: Four fresh frozen head and neck specimens were used and the dissections were done bilaterally. Therefore; totally 8 samples were examined. The samples were prepared according to routine transmission electron microscopic tissue preparation technique. The semi-thin sections were examined under light microscope by camera lucida. In every sample, the quantitative analysis was performed in 5 different areas in an area of 0.01 mm2 and statistical analysis was done. Secondly; the ultrastructural appearance of these terminal branches were examined under transmission electron microscope. RESULTS: In the quantitative analysis of terminal branches of facial nerve in an area of 0.01 mm2; the least number of nerve fibres were found in temporal branches and the highest number were detected in cervical branches. In transmission electron microscopic examination, no significant difference was found in between these branches. In the statistical analysis; statistically significant differences were obtained in between the temporal and buccal, marginal mandibular, cervical branches; zygomatic and marginal mandibular, cervical branches; buccal and marginal mandibular, cervical branches; marginal mandibular and cervical branches. CONCLUSIONS: These numerical data will have an importance during the nerve repair process of terminal branches of facial nerve in various injuries.

Head and neck blocks in infants, children, and adolescents.

This review will discuss the use of peripheral nerve blocks of the head and neck and its application to the practice of pediatric anesthesia using simple, landmark based approaches.

Submandibular approach to the C2-3 disc level: microsurgical anatomy with clinical application.

OBJECT: Approaching the C2-3 disc level is challenging because of its location behind the mandible and the vital neurovascular structures overlying the area. The purpose of this study was to illustrate in a stepwise fashion the microsurgical anatomy of the submandibular approach to the C2-3 disc. METHODS: Ten adult formalin-fixed cadaveric specimens (20 sides) were studied. Particular attention was paid to the structures limiting the exposure. The authors measured the distance between the inferior border of the mandible and the marginal mandibular branch of the facial nerve running inferior to the mandible, the distance between the horizontal segment of the hypoglossal nerve and the hyoid bone, and the distance between the horizontal segment of the hypoglossal nerve and the mandible. They compared the location of the superior laryngeal nerve with regard to the submandibular and the standard Smith-Robinson approaches. A clinical case illustrating the usefulness of the surgical technique in this region is presented. RESULTS: The mean distance between the inferior border of the mandible and the lowest point of the marginal mandibular branch of the facial nerve was 6.7 +/- 1.69 mm. The hypoglossal nerve's mean distance above the hyoid bone was 8.4 +/- 1.78 mm and below the mandible was 19.6 +/- 6.39 mm. The internal branch of the superior laryngeal nerve, with respect to the cervical spine, always entered the thyrohyoid membrane just inferior to the C-3 vertebral body. The superior laryngeal nerve was found to be an impediment to approaching the C2-3 disc through the standard Smith-Robinson approach. CONCLUSIONS: The submandibular approach provides excellent exposure, with a perpendicular view of the C2-3 disc level. This approach is one of the options to be considered when dealing with high cervical pathologies.

Anterior Greater Auricular Point: Novel Anatomic Landmark to Facilitate Harvesting of the Greater Auricular Nerve.

BACKGROUND: The greater auricular nerve (GAN) may be used as a nerve graft during neurosurgical procedures to repair damaged nerves. There is extensive literature on localization of the GAN at the posterior triangle of the neck, but objective information on localization of the GAN at the anterior triangle of the neck close to cranial neurosurgical fields is lacking. The aim of this study was to introduce simple and reliable landmarks to localize the GAN at the anterior triangle of the neck to facilitate its harvest during neurosurgical procedures. METHODS: The GAN was exposed bilaterally in 11 cadaveric specimens at the point of crossing the anterior border of the sternocleidomastoid muscle (anterior greater auricular point [AGA]). Distances from the AGA point to the angle of the mandible and the tip of the mastoid process were measured. Additionally, the location of the crossing point between the GAN and an imaginary line passing through the mastoid tip and the angle of the mandible (M-A line) was found relative to these bony landmarks. RESULTS: Mean (±SD) distances from the AGA point to the mastoid tip and the angle of the mandible were 29.1 ± 3.4 mm and 27.5 ± 4.5 mm, respectively. The GAN was always found to cross the M-A line in its middle third (mean 48.2% ± 6.9% from the mastoid tip). CONCLUSIONS: The AGA point and the M-A line are reliable landmarks for locating the GAN at the anterior triangle of the neck and for helping neurosurgeons expose and harvest the GAN efficiently.

Surgical anatomy of the cervical and infraclavicular parts of the long thoracic nerve.

OBJECT: There is insufficient information in the neurosurgical literature regarding the long thoracic nerve (LTN). Many neurosurgical procedures necessitate a thorough understanding of this nerve's anatomy, for example, brachial plexus exploration/repair, passes for ventriculoperitoneal shunt placement, pleural placement of a ventriculopleural shunt, and scalenotomy. In the present study the authors seek to elucidate further the surgical anatomy of this structure. METHODS: Eighteen cadaveric sides were dissected of the LTN, anatomical relationships were observed, and measurements were obtained between it and surrounding osseous landmarks. The LTN had a mean length of 27 +/- 4.5 cm (mean +/- standard deviation) and a mean diameter of 3 +/- 2.5 mm. The distance from the angle of the mandible to the most proximal portion of the LTN was a mean of 6 +/- 1.1 cm. The distance from this proximal portion of the LTN to the carotid tubercle was a mean of 3.3 +/- 2 cm. The LTN was located a mean 2.8 cm posterior to the clavicle. In 61% of all sides the C-7 component of the LTN joined the C-5 and C-6 components of the LTN at the level of the second rib posterior to the axillary artery. In one right-sided specimen the C-5 component directly innervated the upper two digitations of the serratus anterior muscle rather than joining the C-6 and C-7 parts of this nerve. The LTN traveled posterior to the axillary vessels and trunks of the brachial plexus in all specimens. It lay between the middle and posterior scalene muscles in 56% of sides. In 11% of sides the C-5 and C-6 components of the LTN traveled through the middle scalene muscle and then combined with the C-7 contribution. In two sides, all contributions to the LTN were situated between the middle scalene muscle and brachial plexus and thus did not travel through any muscle. The C-7 contribution to the LTN was always located anterior to the middle scalene muscle. In all specimens the LTN was found within the axillary sheath superior to the clavicle. Distally, the LTN lay a mean of 15 +/- 3.4 cm lateral to the jugular notch and a mean of 22 +/- 4.2 cm lateral to the xiphoid process of the sternum. CONCLUSIONS: The neurosurgeon should have knowledge of the topography of the LTN. The results of the present study will allow the surgeon to better localize this structure superior and inferior to the clavicle and decrease morbidity following invasive procedures.

Parotidectomy combined with identification and preservation procedures of the great auricular nerve.

CONCLUSIONS: We found that the great auricular nerve (GAN) passes at the median (m) point between the tips of the mandibular angle and mastoid process. We also established the GAN definitive line using this point for rapid identification of the trunk of the GAN and systematic parotidectomy combined with procedures for identification of the GAN, elevation of the skin flap, and exposure of the parotid capsule, which showed a high rate of preservation of the nerve and the lobular branch. OBJECTIVE: The aim of this study was to improve parotidectomy and the rate of preservation of the GAN. METHODS: This study comprised 74 consecutive patients who were scheduled to have parotidectomy for benign tumors at our department between November 2011 and April 2014. We examined whether our GAN definitive line including the m point was useful to identify the trunk of the GAN and whether anterograde dissection of the nerve could be performed simultaneously with skin flap elevation and exposure of the parotid capsule and contributed to preservation of the trunk to the lobular branch. RESULTS: The trunk was identified under the GAN definitive line drawn preoperatively in 97.3% of cases (72/74). Combined surgery was successfully performed with a 95.9% (71/74) preservation rate of the GAN including the lobular branch.

Formalin-induced c-fos expression in the spinal cord of fetal rats.

The maturational status of Adelta and C-fibers in the fetal rat spinal cord was examined using formalin-induced c-fos expression as a marker for neuronal activities. Awake 19-, 20-, and 21-day fetuses (FD) were injected ex utero with 5 microl of 10% formalin either into the ventral aspect of the forepaw or the hindpaw. FD 19 fetuses showed little response to the injection, but with increasing age, the fetuses exhibited more specific behaviors following injury of the paw. By FD 21, fetuses treated with formalin injection showed body curls and twitches, mouth opening, face wiping, and withdrawal of the injected paw. The anatomical data paralleled that of behavior; FD 19 animals expressed a small number of Fos labeled nuclei following the formalin injection that was not statistically different from control animals. The formalin-induced increase in Fos staining was first observed at FD 20 with a large increase in the number of Fos labeled cell occurring between FD 20 and 21. By FD 21, the pattern of Fos stained nuclei resembled that found in neonatal rats. There was constitutive bilateral staining in all untreated, saline and formalin injected fetuses that is unique to prenatal animals. Formalin treated fetuses showed constitutive level of staining in addition to the increase in the c-fos expression caused by formalin. We have thus demonstrated that, as indexed both by behavioral response and by Fos immunoreactivity, rat fetuses are capable of transmitting and responding to noxious input before birth.

Update: ansa cervicalis to recurrent laryngeal nerve anastomosis for unilateral laryngeal paralysis.

Twenty cases of unilateral laryngeal paralysis are reported. Satisfactory follow-up intervals and data (videostroboscopy and glottographic analysis) were available on 12 patients. The excellent to normal phonatory quality achieved in many of these patients indicates that the ansa cervicalis to recurrent laryngeal nerve anastomosis is the procedure of choice in selected patients with unilateral vocal cord paralysis. Excellent medialization of the paralyzed cord, as well as correction of arytenoid malposition and thyroarytenoid muscle atrophy appear to explain the technique's success, since the reinnervated cord neither abducts nor adducts. We feel that this technique is the procedure of choice in younger patients, or those who use their voices professionally, since the phonatory quality achieved is superior to Teflon injection or Isshiki thyroplasty, and the technique is reversible.

Sensory changes associated with selective neck dissection.

OBJECTIVE: To evaluate sensory changes in the head and neck region associated with selective neck dissection with or without preservation of cervical root branches. DESIGN: Retrospective cohort study. SETTING: University tertiary referral hospital and a Veterans Affairs hospital. PATIENTS: Fifty-seven patients who had undergone 84 neck dissections with or without preservation of the sensory cervical root branches 3 or more months before evaluation. INTERVENTIONS: Questionnaire combined with head and neck sensory examination. MAIN OUTCOME MEASURES: Neck and facial sensory function. RESULTS: Neck dissections with preservation of the cervical rootlets were most likely to be associated with a small area of anesthesia in the upper neck below the body of the mandible and anterior to the mid-body of the mandible (P=.03). Neck dissections without rootlet-preserving technique increased the area of anesthesia to include all other areas of the neck (P= .02). CONCLUSIONS: Preservation of the cervical root branches resulted in a small, limited, and uniform area of the neck rendered permanently anesthetic. Conversely, sacrifice of the nerve branches led to a pattern of anesthesia involving the entire neck.

The effects of sympathetic trunk stimulation on the position and mobility of the canine tooth of the cat.

The effects of cervical sympathetic trunk stimulation on the position of the maxillary canine tooth and its movements in response to mechanical loading were studied using an ultrasonic transit time technique. Stimulation of the ipsilateral sympathetic trunk for 10-60s and frequencies between 1 and 20 Hz caused both longitudinal and transverse movements of the tooth. Bilateral carotid occlusion caused negligible movements in either direction. When a controlled force was applied in the palatal direction, sympathetic stimulation caused a labial shift of the tip of the tooth and usually an increase in the load-induced palatal displacement; i.e. the mobility of the tooth was increased and appeared to be dependent on the amount of labial shift of the tooth. It is concluded that interference with the vascular component has little, if any, direct effect on the tooth mobility.

Traumatic induced total myelomalacia of the cervical spinal cord associated with a space-occupying subdural hematoma.

We report the case of a 20-year-old male driver who suffered from a trauma to the cervical vertebral column in a head-on collision with a tree. The injuries included subluxation of the 2nd and 3rd cervical vertebrae and fracture of the odontoid process of the axis with ventrally directed displacement of the proximal fragment and dorsally directed displacement of the distal fragment. Already at admission to hospital a space-occupying spinal subdural hematoma was diagnosed. Clinically, paraplegia was diagnosed with progressive loss of consciousness. Pneumonia led to death 40 days after the accident. Autopsy disclosed a total myelomalacia of the cervical spinal cord obviously resulting from an ischemia caused by a traumatic lesion of the dorsal truncus arteriosus spinalis as well as a compression by the spinal subdural hematoma.

Cranial and cervical nerve injuries: local complications of carotid artery surgery.

Injury to the nervous structures extending through the operative field or in areas adjacent to it constitutes a local complication in surgery of the carotid artery. These lesions may become, after an otherwise well-tolerated reconstruction, the source of severe and, occasionally even permanent, complaints. In a series of 536 operations of the carotid artery, 14.4% of transient and 6% of permanent injuries to some of the distal cranial and cervical nerves occurred. The highest injury rate was observed in the hypoglossal nerve (8.6%), followed by the marginal mandibular branch of the facial nerve (6.2%) and the vagus nerve with its superior and recurrent laryngeal branches (3.7% of cases). Injury to the glossopharyngeal nerve and the greater auricular nerve occurs very rarely. A thorough knowledge of the topographic and anatomical situation combined with a cautious operation technique may lower the frequency of these lesions. That is why the essential data on the anatomy, function and the most frequent causes of injury to the individual nerves sustained during surgery within the trigonum caroticum are presented in this article.

Local neurological complication during carotid endarterectomy.

In a prospective study of 52 carotid endarterectomies there were 13 temporary cranial nerve injuries in 12 patients (25%); 7 hypoglossal nerve injuries (13.5%), 3 were asymptomatic (5.8%), 2 had mild speech difficulty (3.8%) and 2 had severe difficulty with deglutition and articulation (3.8%). A full recovery was made within 3 months in all 7 patients. Although 10 patients (19.2%) developed a hoarse voice, indirect laryngoscopy only indicated damage to the ipsilateral recurrent laryngeal nerve in 3 patients (5.8%). Both the voice and vocal cord movement returned to normal within 6 months in 2 patients and a 9 months in the third. The marginal mandibular branch of the facial nerve was injured in 3 patients (5.8%) and all recovered completely within 3 months. Following injury to the great auricular and the transverse cervical nerves injury, 13 patients (25%) had persistent irritation and paraesthesia during shaving and in cold weather lasting up to 18 months after operation. Carotid endarterectomy is associated with a much higher incidence of local nerve injury than retrospective surveys would indicate.

Effect of cervical sympathetic nerve stimulation on nociceptive jaw opening reflex in the cat.

In anaesthetized cats the electrical stimulation of the cervical sympathetic nerve induces a considerable increase (150-250%) in the nociceptive jaw opening reflex elicited by tooth pulp stimulation (JOR). The mechanisms potentially responsible for this effect are discussed and the possibility is suggested, that a portion of the response is due to a modulatory action exerted by the sympathetic on the nociceptive input.

Head and neck symptoms. Is the problem in the ears, face, neck, or oral cavity?

There is a complex anatomic and physiologic relationship among head and neck structures. Because of this complexity, patients with problems in any of these structures often present with a wide range of symptoms and physical findings. The authors describe many head and neck conditions that are encountered in a busy practice and emphasize selection of diagnostic studies and appropriate referral for treatment.