POSTERIOR AURICULAR NERVE – A NOVEL LANDMARK FOR IDENTIFICATION OF THE FACIAL NERVE IN SUPERFICIAL PAROTIDECTOMY

ABSTRACT Background-Facial nerve identification and preservation is the most critical step in parotid surgery. Though there are described landmarks to locate the facial nerve trunk, they have individual variations. The posterior auricular nerve (PAN) is a branch of the facial nerve and is always present, it can be followed to reach the facial nerve trunk. MATERIALS AND METHODS A retrospective cohort study in which analysis of parotidectomy performed from January 2017 to November 2018 at our tertiary referral center was done. RESULTS A total of 23 parotidectomies were performed, of which 18 cases were pleomorphic adenoma. In four cases of pleomorphic adenoma we could clearly identify and preserve the PAN. Using PAN as the landmark the facial nerve trunk was located, all its peripheral branches were dissected and preserved. PAN identification narrows down the target area of dissection to identify the facial nerve trunk. CONCLUSION The posterior auricular branch of the facial nerve can be used as a standard landmark in parotid surgeries, that almost always leads to the facial nerve trunk. CLINICAL SIGNIFICANCE Though identification of PAN may be difficult in all cases, effort must be made to identify it under magnification. If done meticulously PAN can be an ideal landmark to identify facial nerve in parotid surgery. KEYWORDS Parotid surgery, Superficial Parotidectomy, Posterior auricular nerve, Facial nerve.

Predominant role of gut-vagus-brain neuronal pathway in postoperative nausea and vomiting: evidence from an observational cohort study

Background Postoperative nausea and vomiting (PONV) as a clinically most common postoperative complication requires multimodal antiemetic medications targeting at a wide range of neurotransmitter pathways. Lacking of neurobiological mechanism makes this ‘big little problem’ still unresolved. We aim to investigate whether gut-vagus-brain reflex generally considered as one of four typical emetic neuronal pathways might be the primary mediator of PONV. Methods Three thousand two hundred twenty-three patients who underwent vagus nerve trunk resection (esophagectomy and gastrectomy) and non-vagotomy surgery (hepatectomy, pulmonary lobectomy and colorectomy) from December 2016 to January 2019 were enrolled. Thirty cases of gastrectomy with selective resection on the gastric branch of vagus nerve were also recruited. Nausea and intensity of vomiting was recorded within 24 h after the operation. Results PONV occurred in 11.9% of 1187 patients who underwent vagus nerve trunk resection and 28.7% of 2036 non-vagotomy patients respectively. Propensity score matching showed that vagotomy surgeries accounted for 19.9% of the whole PONV incidence, much less than that observed in the non-PONV group (35.1%, P < 0.01). Multivariate logistic regression result revealed that vagotomy was one of underlying factor that significantly involved in PONV (OR = 0.302, 95% CI, 0.237-0.386). Nausea was reported in 5.9% ~ 8.6% vagotomy and 12 ~ 17% non-vagotomy patients. Most vomiting were mild, being approximately 3% in vagotomy and 8 ~ 13% in non-vagotomy patients, while sever vomiting was much less experienced. Furthermore, lower PONV occurrence (10%) was also observed in gastrectomy undergoing selective vagotomy. Conclusion Patients undergoing surgeries with vagotomy developed less PONV, suggesting that vagus nerve dependent gut-brain signaling might mainly contribute to PONV.

The Myth of Median Nerve in Forearm and Its Role in Double Crush Syndrome: A Cadaveric Study

Purpose: This study aims to histologically compare the median nerve in the arm, forearm, and wrist, to help understand how cervical radiculopathy in a double crush phenomenon causes distal nerve dysfunction at the carpal tunnel and median nerve with concurrent absence of symptoms at the forearm.Methods: The study was performed on 12 fresh cadaveric upper limbs free from any injury or operation. Male cadavers in the age range of 35–40 years were used. The dissection of the median nerve and the histological examination of the specimens from the arm, forearm, and wrist were conducted to evaluate variations in the epineurium thickness (μm), perineurium thickness (μm), number of fascicles per nerve trunk, area percent of myelin covering, and area percent of neurolemmal sheath.Results: Morphometric and statistical results of the cadaveric median nerve trunk revealed that the mean epineurium and perineurium thickness measured in H&amp;E-stained sections in the forearm were significantly greater than those in the arm and wrist specimens. Further, the mean percent area of the myelin covering in the forearm was significantly lower than that in the arm and wrist specimens in the sections stained with osmium oxide (p &lt; 0.001). There were, however, no significant differences in the neurolemmal sheath among the arm, forearm, and wrist specimens in the silver-stained sections.Conclusion: The histological differences explained the high concomitant occurrence of carpal tunnel syndrome (CTS) and cervical radiculopathy and the concurrent absence of symptoms at the forearm. Hence, we suggest cautious evaluation of patients with upper limb symptoms, since the management of these conditions requires a different approach.

Peripheral Neuropathy in Leprosy: Clinical Manifestations and Disability in a Colombian National Referral Center

Objective: To describe the neurological features of the physical examination in patients with Hansen’s disease who were treated in Bogotá, Colombia.Methods: We carried out a descriptive study of all patients with a Hansen’s disease diagnosis treated at a referral center between 2003-2018.Results: There were 327 eligible electronic health records (EHRs) with a final sample of 282 subjects. Leprosy was most common in males (57.45%), median age at the diagnosis was 54 years, and lesions of the lower limbs were more common (75.1%). The median time from disease onset to consult was 12 months. Most of them were classified as having lepromatous leprosy (39.7%). Pain over the median nerve trunk was the most common manifestation of disease (28%), followed by pain over the radial trunk (22%). Sensitive alterations were more common than motor ones. Specifically, the posterior tibial nerve was affected in nearly half of subjects. Dual impairment was more common in the ulnar nerve (13.8%). Some disability was apparent in 23.8% of subjects; predominantly grade 1 disability.Conclusion: Findings regarding age, leprosy type, and the frequency of individual nerve compromise were consistent with reports from other countries. Nerve trunk thickening was infrequent, which might be a consequence of subjectiveness in the examination and sample differences in sex distribution, degree of disability and time since disease onset. The frequency of morbidity and disability found in this sample, though low when compared with other series, fails to meet public health goals, including those limiting disability in younger subjects.

Compression neuropathies

Nerve compression disorders affect nerve trunks, particularly in the upper extremity where carpal tunnel syndrome (median nerve compression at the wrist) is the most common and ulnar nerve compression the second most common disorder. Compression affects the various components of the nerve trunk, including the intraneural blood vessels, the Schwann cells, the axons, and the connective tissue components. It results in sensory and motor dysfunction, and sometimes pain. Risk factors for nerve compression disorders are known and may predict surgical outcome. A careful clinical examination should always be done, sometimes complemented with appropriate electrophysiology and magnetic resonance imaging for diagnosis. If conservative treatment is not appropriate, or fails, simple decompression is generally the primary treatment, but problems may persist. The presence of other neuropathies should be considered.

Stereological Study of Changes of GABA-Immunoreactive Neurons in Spinal Dorsal Horn of SNI Rats

Objective. To observe the changes in the mechanical withdrawal threshold (MWT) and the proportion of GABA-immunoreactive neurons in spinal dorsal horn (SDH) of the spared nerve injury (SNI) rat model. Methods. Thirty-six healthy male SD rats were randomly divided into a sham-operated group (group D, n = 18 ) and an SNI group (group S, n = 18 ). The left sciatic nerve trunk and three branches were exposed, two of which, known as tibial and the peroneal nerve, were ligated and cut off. The sural nerve was preserved to build the SNI model in group S. The left sciatic nerve trunk and three branches were only exposed in group D. MWT tests were performed on the medial and lateral sides of the rats’ left hindpaw 1 day before surgery and at 7th, 14th, and 28th day after surgery. Results. In group S, compared with the baseline measured 1 day before surgery, MWT on the medial and lateral sides of the rats’ left hindpaw decreased significantly on the 7th, 14th, and 28th days after surgery ( P < 0.05 ), while in group D, there was no statistically significant difference ( P > 0.05 ). Compared with right SDH, there were not statistically significant reductions in the proportions of GABAergic neurons of left SDH on 7th and 28th day after SNI ( P > 0.05 ); however, the proportion of GABAergic neurons in left SDH significantly decreased, compared with that in right side on 14th day after SNI ( P < 0.05 ). On the same way, the proportions of GABAergic neurons on 7th, 14th, and 28th day after surgery were not statistically different ( P > 0.05 ) in group D. Conclusion. The SNI model could reduce the proportion of GABA-immunoreactive neurons in the rat’s spinal dorsal horn on the nerve-injured side, and this change was lasting, which might be related to the transformation of the GABA-immunoreactive neurons.

Intraoperative infrared fluorescence angiography in surgery of peripheral nerve injuries

Often, when performing reconstruction of nerve trunks, between the ends of the damaged nerve, the presence of diastasis is noted, which requires significant nerve tension in order to overcome it. This, in turn, can lead to a violation of the blood supply to the nerve and damage to its ultrastructures, which leads to unsatisfactory treatment results. The possibility of using intraoperative infrared fluorescence angiography in reconstructive surgical interventions for peripheral nerve damage, in order to assess the degree of blood flow disturbance in the nerve trunk, is considered. In patients with a complete anatomical break during the operation, an attempt was made to overcome diastasis by measuring the tension force (up to 3 N) with which the nerve was affected. Infrared fluorescence angiography with indocyanine green was performed simultaneously. The obtained angiograms were analyzed, and the effect of the tension force on the change in blood flow in the nerve trunk was determined. It was found that when exposed to a force of up to 2 N, there is no significant change in the intraneural blood flow. At the same time, the effect of a force of 3 N is manifested on angiograms by a significant decrease in the volume of blood flow, which is usually due to constriction of the vessels due to their stretching. After reconstruction (microsurgical epineural suture), repeated angiography was performed to assess the safety and adequacy of blood supply to the nerve. It was revealed that the use of intraopreational angiography with indocyanin green is an affordable and easily feasible technique that allows to determine the safety and, equally important, the adequacy and efficiency of blood flow in the nerve trunk. This technique makes it possible to monitor the safety of blood flow in the nerve trunk, to study the mechanisms of compensation of blood supply to the nerve after microsurgical epineural suture, to assess the quality of comparison of nerve stumps along the axis, excluding the possibility of their "twist".