The Great Auricular Nerve Trigger Site: Anatomy, Compression Point Topography, and Treatment Options for Headache Pain.

BACKGROUND: Peripheral nerve decompression surgery can effectively address headache pain caused by compression of peripheral nerves of the head and neck. Despite decompression of known trigger sites, there are a subset of patients with trigger sites centered over the postauricular area coursing. The authors hypothesize that these patients experience primary or residual pain caused by compression of the great auricular nerve. METHODS: Anatomical dissections were carried out on 16 formalin-fixed cadaveric heads. Possible points of compression along fascia, muscle, and parotid gland were identified. Ultrasound technology was used to confirm these anatomical findings in a living volunteer. RESULTS: The authors' findings demonstrate that the possible points of compression for the great auricular nerve are at Erb's point (point 1), at the anterior border of the sternocleidomastoid muscle in the dense connective tissue before entry into the parotid gland (point 2), and within its intraparotid course (point 3). The mean topographic measurements were as follows: Erb's point to the mastoid process at 7.32 cm/7.35 (right/left), Erb's point to the angle of the mandible at 6.04 cm/5.89 cm (right/left), and the posterior aspect of the sternocleidomastoid muscle to the mastoid process at 3.88 cm/4.43 cm (right/left). All three possible points of compression could be identified using ultrasound. CONCLUSIONS: This study identified three possible points of compression of the great auricular nerve that could be decompressed with peripheral nerve decompression surgery: Erb's point (point 1), at the anterior border of the sternocleidomastoid muscle (point 2), and within its intraparotid course (point 3).

Efficacy of surgical repair for the functional restoration of injured facial nerve.

BACKGROUND: Early surgical repair to restore nerve integrity has become the most commonly practiced method for managing facial nerve injury. However, the evidence for the efficacy of surgical repair for restoring the function of facial nerves remains deficient. This study evaluated the outcomes of surgical repair for facial nerve lesions. METHODS: This retrospective observational study recruited 28 patients with the diagnosis of facial nerve injury who consecutively underwent surgical repairs from September 2012 to May 2019. All related clinical data were retrospectively analyzed according to age, sex, location of the facial nerve lesion, size of the facial nerve defect, method of repair, facial electromyogram, and blink reflex. Facial function was then stratified with the House-Brackmann grading system pre-operation and 3, 9, 15, and 21 months after surgical repair. RESULTS: The 28 patients enrolled in this study included 17 male and 11 female patients with an average age of 34.3 ± 17.4 years. Three methods were applied for the repair of an injured facial nerve, including great auricular nerve transplantation in 15 patients, sural nerve grafting in 7 patients, and hypoglossal to facial nerve anastomosis in 6 patients. Facial nerve function was significantly improved at 21 months after surgery compared with pre-operative function (P = 0.008). Following surgical repair, a correlation was found between the amplitude of motor unit potential (MUP) and facial nerve function (r = -6.078, P = 0.02). Moreover, the extent of functional restoration of the facial nerve at 21 months after surgery depended on the location of the facial nerve lesion; lesions at either the horizontal or vertical segment showed significant improvement(P = 0.008 and 0.005), while no functional restoration was found for lesions at the labyrinthine segment (P = 0.26). CONCLUSIONS: For surgical repair of facial nerve lesions, the sural nerve, great auricular nerve, and hypoglossal-facial nerve can be grafted effectively to store the function of a facial nerve, and MUP may provide an effective indicator for monitoring the recovery of the injured nerve.

Immediate Intraoperative Repair of the Recurrent Laryngeal Nerve in Thyroid Surgery.

OBJECTIVES: Recurrent laryngeal nerve (RLN) injury is a recognized risk during thyroid and parathyroid surgery and can result in significant morbidity. The aim of this review paper is to consider the optimal approach to the immediate intraoperative repair of the RLN during thyroid surgery. METHODS: A PubMed literature search was performed from inception to June 2020 using the following search strategy: immediate repair or repair recurrent laryngeal nerve, repair or reinnervation recurrent laryngeal nerve and immediate neurorraphy or neurorraphy recurrent laryngeal nerve. RESULTS: Methods of immediate intraoperative repair of the RLN include direct end-to-end anastomosis, free nerve graft anastomosis, ansa cervicalis to RLN anastomosis, vagus to RLN anastomosis, and primary interposition graft. Techniques of nerve repair include micro-suturing, use of fibrin glue, and nerve grafting. Direct micro-suture is preferable when the defect can be repaired without tension. Fibrin glue has also been proposed for nerve repair but has been criticized for its toxicity, excessive slow reabsorption, and the risk of inflammatory reaction in the peripheral tissues. When the proximal stump of the RLN cannot be used, grafting could be done using transverse cervical nerve, supraclavicular nerve, vagus nerve, or ansa cervicalis. CONCLUSIONS: Current evidence is low-level; however, it suggests that when the RLN has been severed, avulsed, or sacrificed during thyroid surgery it should be repaired intraoperatively. The immediate repair has on balance more advantages than disadvantages and should be considered whenever possible. This should enable the maintenance of vocal cord tone, better and prompter voice recovery and avoidance of aspiration. Laryngoscope, 131:1429-1435, 2021.

In-Depth Look at the Anatomical Relationship of the Lesser Occipital Nerve, Great Auricular Nerve, and Spinal Accessory Nerve and Their Implication in Safety of Operations in the Posterior Triangle of the Neck.

BACKGROUND: Migraine surgery is an increasingly popular treatment option for migraine patients. The lesser occipital nerve is a common trigger point for headache abnormalities, but there is a paucity of research regarding the lesser occipital nerve and its intimate association with the spinal accessory nerve. METHODS: Six cadaver necks were dissected. The lesser occipital, great auricular, and spinal accessory nerves were identified and systematically measured and recorded. These landmarks included the longitudinal axis (vertical line drawn in the posterior), the horizontal axis (defined as a line between the most anterosuperior points of the external auditory canals) and the earlobe. Mean distances and standard deviations were calculated to delineate the relationship between the spinal accessory, lesser occipital, and great auricular nerves. RESULTS: The point of emergence of the spinal accessory nerve was determined to be 7.17 ± 1.15 cm lateral to the y axis and 7.77 ± 1.10 caudal to the x axis. The lesser occipital nerve emerges 7.5 ± 1.31 cm lateral to the y axis and 8.47 ± 1.11 cm caudal to the x axis. The great auricular nerve emerges 8.33 ± 1.31 cm lateral to the y axis and 9.4 ±1.07 cm caudal to the x axis. The decussation of the spinal accessory and the lesser occipital nerves was found to be 7.70 ± 1.16 cm caudal to the x axis and 7.17 ± 1.15 lateral to the y axis. CONCLUSION: Understanding the close relationship between the lesser occipital nerve and spinal accessory nerve in the posterior, lateral neck area is crucial for a safer approach to occipital migraine headaches, occipital neuralgia, and new daily persistent headaches and other reconstructive or cosmetic operations.

Contralateral C7 transfer to axillary and median nerves in rats with total brachial plexus avulsion.

BACKGROUND: Contralateral cervical 7 nerve (cC7) was used to repair two recipient nerves simultaneously for patients with total brachial plexus avulsion (TBPA). OBJECTIVE: To evaluate the effect of cC7 transfer to axillary and median nerves in rats with TBPA. METHODS: Eighty S-D rats were divided into 4 groups randomly on average. Group A: cC7-median nerve, Group B: cC7-axillary nerve, Group C: cC7-median and axillary nerves, Group D: TBPA without repair. The evaluation tools included behavioral tests, electromyogram (EMG), measurement of cross-sectional area of muscle fiber, nerve fiber count and gene expression assay. RESULTS: The effective rates of EMG were 90 and 70% in Flexor Carpi Radialis (FCR) in Group A and C, while 70 and 60% in deltoid (DEL) in Group B and C, respectively. In behavioral test, the differences of effective rates between groups were not significant. The mean cross-sectional area of FCR in Group A or C was significantly larger than that in Group D. Either the number of median or axillary nerve fibers in Group A, B or C was statistically more than that in Group D. No matter for FCR or DEL, there were no significant differences in the ratios of relative expression of Muscle Atrophy F-box(MAFBOX)and Muscle RING Finger 1(MURF1)among these groups. CONCLUSION: Compared with cC7 transfer to median nerve, cC7 transfer to both median and axillary nerves did not affect median nerve recovery. The deltoid muscle also could be restored. The recovery proportion of axillary nerve was less than that of median nerve.

Schwannoma del plexo cervical en una mujer de 76 años / Schwannoma of the cervical plexus in a 76-year-old woman

No disponible

Vagal stimulation and laryngeal electromyography for recurrent laryngeal reinnervation in children.

Ansa-to-recurrent laryngeal nerve (ANSA-RLN) reinnervation procedures are now often first-line treatments for some children with unilateral vocal fold immobility. Although many describe that children with prolonged denervation and true vocal fold atrophy should not undergo this procedure, there has been no gold-standard means of identifying true denervation. Here, we describe a novel technique using evoked vagal electromyography to predict degree of chronic nerve injury prior to recurrent laryngeal nerve reinnervation in children. This is a simple, readily available technique that may play an important role in predicting likelihood of success with pediatric ANSA-RLN reinnervation. Laryngoscope, 130:747-751, 2020.

Lessons learned to aid the successful outcome of pediatric recurrent laryngeal nerve reinnervation.

While Ansa to recurrent laryngeal nerve reinnervation is gaining popularity in the treatment of unilateral vocal fold immobility, little has been reported on commonly encountered surgical challenges with this procedure. Here, we present a cohort of 21 pediatric patients who underwent this procedure with a full description of techniques used to overcome common challenges with this procedure. We report vocal and swallowing outcomes for these patients, with an overall success rate of 19/21 (90.5%) patients, with success defined as improvement of a half-consistency or resolution of vocal issues.

Main branch of ACN-to-RLN for management of laryngospasm due to unilateral vocal cord paralysis.

OBJECTIVES/HYPOTHESIS: This study explored the feasibility and efficiency of main branch of ansa cervicalis nerve (ACN)-to-recurrent laryngeal nerve (RLN) anastomosis for management of paroxysmal laryngospasm due to unilateral vocal cord paralysis (UVCP). METHODS: Thirteen patients who underwent main branch of ACN-to-RLN anastomosis for management of paroxysmal laryngospasm due to UVCP were enrolled in the present study. Multidimensional assessments, including videostroboscopy, voice assessment, and laryngeal electromyography (LEMG), were performed preoperatively and postoperatively. RESULTS: This series was limited to UVCP with iatrogenic causes, including thyroidectomy, cervical spine surgery, and thoracic surgery. After main branch of ACN-to-RLN anastomosis, all cases showed significant airway improvement, and laryngospasm was completely abolished in 92.3% (12 of 13) of cases. Videostroboscopy showed that the bulging and paradoxical adduction of the affected vocal cord during a sniff were abolished immediately after operation, and there was no significant difference in vocal fold position or glottal closure before versus after the operation. LEMG showed that the postoperative recruitment and amplitude of voluntary motor unit potential in the affected thyroarytenoid muscle during a sniff were significantly decreased compared to preoperative values, and postoperative recruitment showed significant improvement during phonation compared to that preoperatively. Voice assessment showed that there were no significant differences in overall grade, roughness, breathiness, jitter (local), shimmer (local), noise-to-harmonics ratio, or maximum phonation time after the operation compared to the preoperative values. CONCLUSIONS: Main branch of ACN-to-RLN anastomosis could have long-lasting efficacy in the management of paroxysmal laryngospasm due to UVCP, with no apparent compromise of voice quality. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:2412-2419, 2020.

Great Auricular Neuralgia: Case Series.

BACKGROUND/OBJECTIVE: The great auricular nerve (GAN) arises from C2-C3 and provides innervation over the skin in the pre-auricular region, jaw angle, posteroinferior pinna, and mastoid. Although damage to the GAN has been reported following trauma or procedures nearby this nerve course, neuralgia of this nerve is uncommon with knowledge based on a handful of case reports in literature. The objective of this study is to describe the presentation, treatment, and outcome of 13 cases of GAN neuralgia. METHODS: Case series. Retrospecive review of charts from 1994 to 2018 with diagnoses: "auricular neuralgia," "auricular neuritis," or "auricular neuropathy." We included subjects with neuralgic pain within the distribution of the GAN, and excluded patients with atypical facial pain, GAN neuropathy, or unclear etiology. RESULTS: Of 79 charts, 13 patients met criteria (age at onset 11-59; 11 women, 2 men). Pain was most often described as paroxysmal stabbing provoked by: turning the head (n = 7), touching the neck (n = 5), neck position during sleep (n = 2), jaw movement (n = 2), and other (n = 2). Seven patients received GAN blocks: all noted dramatic improvement in pain, including 3 who continued to receive serial blocks at our institution successfully for the next 2 to 5 years. Two patients successfully transitioned from GAN blocks to GAN stimulators. One patient with GAN lymphoma had resolution of pain following GAN resection. CONCLUSION: GAN neuralgia should be considered in the differential for periauricular pain. GAN blocks or stimulators may be helpful for pain management.

An Anatomical Feasibility Study Using a Great Auricular Nerve Graft for Ipsilateral Inferior Alveolar Nerve Repair.

The great auricular nerve (GAN) has been used for trigeminal and facial nerve repair and the inferior alveolar nerve (IAN) are often sacrificed during segmental mandibulectomy. To our knowledge, only 1 case report has discussed IAN repair using GAN after segmental mandibulectomy. The goal of this study is to clarify the feasibility of using GAN for IAN repair. Eleven sides from 6 fresh frozen Caucasian cadavers were used for this study. The mean age at the time of death was 82.3 years. A submandibular skin incision was made 2 finger breadths below and parallel to the inferior border of the mandible. The GAN was identified and then the mental foramen was found via extraoral dissection. The buccal cortical bone was removed 5 mm posterior to the mental foramen to the wisdom tooth area. Next, the anteroposterior length of the window was measured. The diameter of the IAN at the first molar tooth area was measured. Finally, the GAN was cut with maximum available length to compare to the length of the window in the mandible. The anteroposterior length of the window and diameter of the IAN ranged from 23.1 to 31.2 mm and 1.2 to 2.1 mm, respectively. The length of the available GAN was longer than the ipsilateral bony window of the mandible on all sides. This study might encourage surgeons to consider a new way to treat patients who undergo segmental resection of the mandible with surgical neck dissection with injury to their IAN.

Novel Nerve Transfers for Motor and Sensory Restoration in High Cervical Spinal Cord Injury.

BACKGROUND: Tetraplegia caused by cervical spinal cord injury is devastating for patients and represents a significant public health problem in both developed and developing countries. Improved functional outcomes after nerve transfers are increasingly reported in the literature, but thus far, no options exist for injuries above the C5 level. CASE DESCRIPTION: We report the cases of 2 patients with C4 spinal cord injury, American Spinal Injury Association A, who underwent successful bilateral spinal accessory nerve transfers, on 1 side to the triceps nerve with long intervening sural graft and on the other side direct transfer to the motor fascicles of the middle trunk. Patients improved from Medical Research Council 0 to 4 on the side of the nerve graft and 0 to 2 or 3 on the side of the direct transfer. Both patients also underwent transfer of the greater auricular nerve to sensory fascicles of the middle trunk, and they experienced sensory recovery in the C6 distribution. Notably, both patients were far removed from the traditional window of nerve transfer surgery at 4 years and almost 11 years out from injury. CONCLUSIONS: We describe 2 successful cases of the first and to date only option for motor and sensory reinnervation in high cervical spinal cord injuries. These procedures provide a robust nerve transfer option capable of improving quality of life in tetraplegic patients. There may be a significant undertreated population of patients with cervical spinal cord injury patients in the United States who were previously considered outside the window for benefiting from nerve transfers but who would benefit from these techniques.

Delayed surgical site infection 2 years after cervical disk arthroplasty. Case report and literature review / Infección diferida del sitio quirúrgico 2 años después de la artroplastia de disco cervical. Caso clínico y revisión de la literatura

Anterior cervical discectomy has a low non-mechanical complication rate. In our literature review, we found 7 cases of delayed surgical site infection. We report a case of cervical prevertebral abscess due to Propionibacterium acnes 2 years after discectomy and arthroplasty, with a beta-2-transferrin false positive test as a complementary highlighted finding. We discuss the diagnosis and etiology of this rare delayed infectious complication

La discectomía cervical anterior tiene una baja tasa de complicaciones no mecánicas. En la revisión de la literatura, encontramos 7 casos de infección diferida del sitio quirúrgico. Presentamos un caso de absceso cervical prevertebral secundario a Propionibacterium acnes 2 años después de la cirugía, asociado a un falso positivo del test de beta-2-transferrina como hallazgo complementario a destacar, y discutimos el diagnóstico y la etiología de esta rara complicación infecciosa diferida

Immediate selective laryngeal reinnervation in vagal paraganglioma patients.

OBJECTIVE: This prospective case series aimed to present the outcomes of immediate selective laryngeal reinnervation. METHODS: Two middle-aged women with vagal paraganglioma undergoing an excision operation underwent immediate selective laryngeal reinnervation using the phrenic nerve and ansa cervicalis as the donor nerve. Multidimensional outcome measures were employed pre-operatively, and at 1, 6 and 12 months post-operatively. RESULTS: The voice handicap index-10 score improved from 23 (patient 1) and 18 (patient 2) at 1 month post-operation, to 5 (patient 1) and 1 (patient 2) at 12 months. The Eating Assessment Tool 10 score improved from 20 (patient 1) and 24 (patient 2) at 1 month post-operation, to 3 (patient 1) and 1 (patient 2) at 12 months. There was slight vocal fold abduction observed in patient one and no obvious abduction in patient two. CONCLUSION: Selective reinnervation is safe to perform following vagal paraganglioma excision conducted on the same side. Voice and swallowing improvements were demonstrated, but no significant vocal fold abduction was achieved.

Pros and Cons of C2 Nerve Sectioning/Preservation in Posterior Fusion for Congenital Atlantoaxial Dislocation.

OBJECTIVE: Deliberate C2 nerve root sectioning and its preservation have been described during posterior fusion for atlantoaxial dislocation (AAD). However, the associated outcomes have been less studied, especially in congenital AAD. Our objective was to study the clinical outcomes after C2 nerve root sectioning and the feasibility of C2 preservation in these patients. METHODS: The data from 190 patients were retrospectively studied. The decision to cut or preserve the C2 nerve root was determined by the preoperative radiologic findings and intraoperative suitability of its preservation. During follow-up, the patients were questioned about C2 nerve-related dysfunction. The pros and cons of sectioning or preservation of the C2 nerve root and the related feasibility factors are also described. RESULTS: Complex C1-C2 anatomy that required extensive dissection and drilling was seen in 139 patients. After C2 nerve root sectioning in 178 patients, none reported bothersome hypoesthesia, paresthesia, or dysesthesia that required medication. However, 9 patients (5.1%) developed nonhealing occipital ulcers and most required flap coverage or a skin graft. C2 nerve root preservation is feasible with an adequate inferior C1 lateral mass and normal-size ganglion. In patients with C1-occipital condyle hypoplasia, extremely oblique joints, spondyloptosis, incurved occiput, pseudofacets, and anomalous vertebral artery, preservation of the C2 nerve root is difficult. CONCLUSIONS: The advantages of sectioning the C2 nerve root are many. However, a subset of patients is prone to morbid occipital neuropathic ulcers. After C2 nerve sectioning, one should be cautious of such complications. C2 nerve root preservation should be strongly considered for patients with favorable anatomy.

Treatment of unilateral vocal fold paralysis with ansa cervicalis to recurrent nerve anastomosis in a young adolescent: European case report.

BACKGROUND: Laryngeal re-innervation in paediatric unilateral vocal fold paralysis is a relatively new treatment option, of which there has been little reported experience in Europe. METHODS: In this European case report of a 13-year-old boy with dysphonia secondary to left-sided unilateral vocal fold paralysis after cardiac surgery, the patient underwent re-innervation using an ansa cervicalis to recurrent laryngeal nerve transfer, in combination with fat augmentation, after 12 years of nerve denervation. Perceptual analysis data, and acoustic and laryngoscopy recordings were acquired pre-operatively, and at one and two years post-operatively. RESULTS: The patient's perceptual voice quality was improved. He experienced subjective improvement and is very satisfied with the result. As expected, laryngoscopy at one and two years after surgery showed no physiological mobility of the vocal fold concerned, but improved closure during phonation was achieved. Electromyography showed evidence of re-innervation. CONCLUSION: Laryngeal re-innervation could be considered as a treatment option for unilateral vocal fold paralysis in children and adolescents, even after a long-term delay.

Surgical Approach to Injuries of the Cervical Plexus and Its Peripheral Nerve Branches.

BACKGROUND: Located in the neck beneath the sternocleidomastoid muscle, the cervical plexus comprises a coalition of nerves originating from C1 through C4, which provide input to four cutaneous, seven motor, and three cranial nerves and the sympathetic trunk. Sporadic instances of injury to these superficial nerves have been reported. Nevertheless, this specific anatomical cause of neurogenic pain remains incompletely described and underrecognized. METHODS: Twelve patients presented with pain and were diagnosed with various combinations of injury to the lesser occipital, great auricular, transverse cervical, and supraclavicular nerves. Inciting events included prior face lift, migraine, and thoracic outlet procedures; and traumatic events including seatbelt trauma, a fall, and a clavicular fracture. History and examination suggested injury to the cervical plexus, and nerve blocks confirmed the diagnoses. Neurectomy with intramuscular transposition was performed for three nerve branches in one patient, two branches in two patients, and one branch in the remaining nine patients. RESULTS: Nine of the twelve patients had complete relief of their cervical plexus-related pain. The three failures were in patients with pain after previous face-lift surgery. Residual perception of neck tightness and choking sensation persisted despite relief of cheek and ear pain. CONCLUSIONS: Knowledge of the cervical plexus anatomy and its branches is crucial for surgeons operating in this area to minimize iatrogenic nerve injury. In addition, neuromas should be considered a likely cause of pain and dysesthesia following surgery or injury. Proper diagnosis and surgical intervention can have a significantly positive effect on these debilitating problems. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Surgical Methods and Experiences of Surgeons did not Significantly Affect the Recovery in Phonation Following Reconstruction of the Recurrent Laryngeal Nerve.

BACKGROUND: We reported phonatory recovery in the majority of 88 patients after recurrent laryngeal nerve (RLN) reconstruction. Here we analyzed factors that might influence the recovery, in a larger patient series. METHODS: At Kuma Hospital, 449 patients (354 females and 95 males) underwent RLN reconstruction with direct anastomosis, ansa cervicalis-to-RLN anastomosis, free nerve grafting, or vagus-to-RLN anastomosis; 47.4 % had vocal cord paralysis (VCP) preoperatively. Maximum phonation time (MPT) and mean airflow rate during phonation (MFR) were measured 1 year post surgery. Forty patients whose unilateral RLNs were resected and not reconstructed and 1257 normal subjects served as controls. RESULTS: Compared to the VCP patients, the RLN reconstruction patients had significantly longer MPTs 1 year after surgery, nearing the normal values. The MFR results were similar but less clear. Detailed analyses of 228 female patients with reconstruction for whom data were available revealed that none of the following factors significantly affected phonatory recovery: age, preoperative VCP, method of reconstruction, site of distal anastomosis, use of magnifier, thickness of suture thread, and experience of surgeon. Of these 228 patients, 24 (10.5 %) had MPTs <9 s 1 year after surgery, indicating insufficient recovery in phonation. This insufficiency was also not associated with the factors mentioned above. CONCLUSIONS: Approximately 90 % of patients who needed resection of the RLN achieved phonatory recovery following RLN reconstruction. The recovery was not associated with gender, age, preoperative VCP, surgical method of reconstruction, or experience of the surgeon. Performing reconstruction during thyroid surgery is essential whenever the RLN is resected.

A Central Role for Sympathetic Nerves in Herpes Stromal Keratitis in Mice.

PURPOSE: Herpes simplex virus type 1 (HSV-1) is a neurotrophic virus that can cause herpes stromal keratitis (HSK), a severe corneal inflammation that can lead to corneal scarring and blindness. This study identified neurologic changes that occur in HSV-1-infected corneas and related them to HSV-1-induced immunopathology. METHODS: Corneas of BALB/c and C57BL/6 mice were infected with HSV-1 strains that induce HSK. Changes in sensory nerves were identified by immunofluorescence staining of sensory and sympathetic nerves for substance P (SP) and tyrosine hydroxylase (TH), respectively, and confocal microscopic examination. Some mice received superior cervical ganglionectomy (SCGx) to eliminate sympathetic nerves from the cornea. RESULTS: Normal corneas exclusively expressed sensory nerves that entered the stroma as large nerve stalks, branched to form a plexus at the epithelial/stromal interface, and extended termini into the epithelium. These nerves completely retracted from the infected cornea and were replaced by sympathetic nerves that sprouted extensively to hyperinnervate the corneal stroma but failed to form a plexus or extend termini into the epithelium. The hyperinnervating nerves expressed the sympathetic nerve marker TH and their invasion was blocked by performing SCGx. Moreover, the corneal opacity and neovascularization that normally characterizes HSK in this mouse model were largely abrogated by SCGx. Sensory nerves reinnervated infected corneas following SCGx, reformed a nerve plexus, and extended termini into the epithelium resulting in recovery of corneal sensitivity. CONCLUSIONS: Sympathetic nerves have a central role in HSK in mice, preventing reinnervation by sensory nerves and promoting severe and persistent corneal inflammation.