Ultrasound-guided selective glossopharyngeal nerve block: posterior mandibular ramus approach.

OBJECTIVE: Glossopharyngeal nerve block is a useful interventional technique for pain management of the head and neck. It is performed with landmark techniques or ultrasound guidance. We propose a novel ultrasound-guided glossopharyngeal nerve block technique. METHODS: This new approach was performed in 3 patients in their twenties and thirties. A needle was inserted deeply under the stylohyoid muscle through the sternocleidomastoid muscle. Subsequently, an ultrasound-guided nerve block was performed with 1 mL of 1% xylocaine. The performance of our technique was evaluated with 2 tests: a cold sensitivity test and a gag reflex test. RESULTS: The effect of the nerve block was observed in the posterior third of the tongue on both sides, the tonsils, and the pharyngeal region. The effect lasted for approximately 1.5 hour. Motor efferent block was not observed. CONCLUSIONS: We designated the technique as ultrasound-guided selective glossopharyngeal nerve block: posterior mandibular ramus approach. No complications occurred during the bilateral application. This novel approach can be performed at a very shallow position, compared with conventional methods. There is no damage to tissues other than the muscles, which reduces postoperative complications and patient distress. Although our technique requires further safety assessments and technical refinements, it could represent a simpler alternative to conventional methods in daily clinical practice.

Microsurgical anatomy of the glossopharyngeal nerve.

The glossopharyngeal nerve is a complicated and mixed nerve including sensory, motor, parasympathetic, and visceral fibers. It mediates taste, salivation, and swallowing. The low cranial nerves, including IXth, Xth, and XIth, are closely related, sharing some nuclei in the brainstem. The glossopharyngeal nerve arises from the spinal trigeminal nucleus and tract, solitary tract and nucleus, nucleus ambiguous, and inferior salivatory nucleus in the brainstem. There are communicating branches forming a neural anastomotic network between low cranial nerves. Comprehensive knowledge of the anatomy of the glossopharyngeal nerve is crucial for performing surgical procedures without significant complications. This review describes the microsurgical anatomy of the glossopharyngeal nerve and illustrates some pictures involving the glossopharyngeal nerve and its connective and neurovascular structures.

The Location of the Parasympathetic Fibres within the Vagus Nerve Rootlets: A Case Report and a Review of the Literature.

The vagus nerve has motor, sensory, and parasympathetic components. Understanding the nerve's internal anatomy, its variations, and relationship to the glossopharyngeal nerve are crucial for neurosurgeons decompressing the lower cranial nerves. We present a case report demonstrating the location of the parasympathetic fibres within the vagus nerve rootlets. A 47-year-old woman presented with a 1-year history of medically refractory left-sided glossopharyngeal neuralgia and a more recent history of left-sided hemi-laryngopharyngeal spasm. magnetic resonance imaging showed her left posterior inferior cerebellar artery distorting the lower cranial nerves on the affected left side. The patient consented to microvascular decompression of the lower cranial nerves with possible sectioning of the glossopharyngeal and upper sensory rootlets of the vagus nerve. During surgery, electrical stimulation of the most caudal rootlet of the vagus nerve triggered profound bradycardia. None of the more rostral rootlets had a similar parasympathetic response. This case is the first demonstration, to our knowledge, of the location of the cardiac parasympathetic fibres within the human vagus nerve rootlets. This new understanding of the vagus nerve rootlets' distribution of pure sensory (most rostral), motor/sensory (more caudal), and parasympathetic (most caudal) fibres may lead to a better understanding and diagnosis of the vagal rhizopathies. Approximately 20% of patients with glossopharyngeal neuralgia also have paroxysmal cough. This could be due to the anatomical juxtaposition of the IXth cranial nerve with the rostral vagal rootlets with pure sensory fibres (which mediate a tickling sensation in the lungs). A subgroup of patients with glossopharyngeal neuralgia have neuralgia-induced syncope. The cause of this rare condition, "vago-glossopharyngeal neuralgia," has been debated since it was first described by Riley in 1942. Our case supports the theory that this neuralgia-induced bradycardia is reflexively mediated through the brainstem with afferent impulses in the IXth and efferent impulses in the Xth cranial nerve. The rarer co-occurrence of glossopharyngeal neuralgia with hemi-laryngopharyngeal spasm (as seen in this case) may be explained by the proximity of the IXth nerve with the more caudal vagus rootlets which have motor (and probably sensory) supply to the throat. Finally, if there is a vagal rhizopathy related to compression of its parasympathetic fibres, one would expect it to be at the most caudal rootlet of the vagus nerve.

Current advances in the surgical treatment of glossopharyngeal neuralgia.

Glossopharyngeal neuralgia (GPN) is a neurological condition characterized by paroxysmal, stabbing-like pain along the distribution of the glossopharyngeal nerve that lasts from a couple of seconds to minutes. Pharmacological treatment with anticonvulsants is the first line of treatment; however, about 25% of patients remain symptomatic and require surgical intervention, which is usually done via microvascular decompression (MVD) with or without rhizotomy. More recently, the use of stereotactic radiosurgery (SRS) has been utilized as an alternative treatment method to relieve patient symptoms by causing nerve ablation. We conducted a systematic review to analyze whether MVD without rhizotomy is an equally effective treatment for GPN as MVD with the use of concurrent rhizotomy. Moreover, we sought to explore if SRS, a minimally invasive alternative surgical option, achieves comparable outcomes. We included retrospective studies and case reports in our search. We consulted PubMed and Medline, including articles from the year 2000 onwards. A total of 36 articles were included for review. Of all included patients with glossopharyngeal neuralgia, the most common offending artery compressing the glossopharyngeal nerve was the posterior inferior cerebellar artery (PICA). MVD alone was successful achieving pain relief immediately postoperatively in about 85% of patients, and also long term in 65-90% of patients. The most common complication found on MVD surgery was found to be transient hoarseness and transient dysphagia. Rhizotomy alone shows an instant pain relief in 85-100% of the patients, but rate of long-term pain relief was lower compared to MVD. The most common adverse effects observed after a rhizotomy were dysphagia and dysesthesia along the distribution of the glossopharyngeal nerve. SRS had promising results in pain reduction when using 75 Gy radiation or higher; however, long-term rates of pain relief were lower. MVD, rhizotomy, and SRS are effective methods to treat GPN as they help achieve instant pain relief and the decrease use of medication. Patients with MVD alone presented with less adverse effects than the group that underwent MVD plus rhizotomy. Although SRS may be a viable alternative treatment for GPN, further studies must be done to evaluate long-term treatment efficacy.

Anatomy of small canals around the jugular foramen: Special reference to Jacobson's and Arnold's nerves.

The jugular foramen harbors anatomically complex bony, venous and neural structures. It is closely associated with small canals including the mastoid, tympanic, and cochlear canaliculi, and the stylomastoid foramen. The minute intraosseous branches of Arnold's and Jacobson's nerves (<1 mm in length) remain difficult to study with current imaging techniques, and cadaveric dissection is the most reliable approach. Our aim was to examine the variations of Jacobson's and Arnold's canaliculi and nerves and to provide detailed cadaveric graphics. To reveal the anatomical structures of small canals around the jugular foramen, 25 sides of dry skulls and 14 sides of cadaveric heads were examined. Intraosseous branches varied more in Arnold's nerve than Jacobson's nerve. In our cadaveric dissection, all specimens formed a single canal for Jacobson's nerve connecting the jugular foramen to the tympanic cavity. The intraosseous course of Arnold's nerve varied in its communication with the facial nerve. A descending branch crossing the facial nerve was identified in five of 14 sides, an ascending branch in 13. In two specimens, an ascending branch clearly reached the base of the stapedius muscle. Classical anatomical studies of cadavers remain a supplementary tool for analyzing these tiny structures. The present study confirms Gray's findings of 1913. Variations of these nerves could be even more complex than previously reported. Our study provides additional information regarding the anatomy of Jacobson's and Arnold's nerves.

Anterior and Posterior Tongue Regions and Taste Papillae: Distinct Roles and Regulatory Mechanisms with an Emphasis on Hedgehog Signaling and Antagonism.

Sensory receptors across the entire tongue are engaged during eating. However, the tongue has distinctive regions with taste (fungiform and circumvallate) and non-taste (filiform) organs that are composed of specialized epithelia, connective tissues, and innervation. The tissue regions and papillae are adapted in form and function for taste and somatosensation associated with eating. It follows that homeostasis and regeneration of distinctive papillae and taste buds with particular functional roles require tailored molecular pathways. Nonetheless, in the chemosensory field, generalizations are often made between mechanisms that regulate anterior tongue fungiform and posterior circumvallate taste papillae, without a clear distinction that highlights the singular taste cell types and receptors in the papillae. We compare and contrast signaling regulation in the tongue and emphasize the Hedgehog pathway and antagonists as prime examples of signaling differences in anterior and posterior taste and non-taste papillae. Only with more attention to the roles and regulatory signals for different taste cells in distinct tongue regions can optimal treatments for taste dysfunctions be designed. In summary, if tissues are studied from one tongue region only, with associated specialized gustatory and non-gustatory organs, an incomplete and potentially misleading picture will emerge of how lingual sensory systems are involved in eating and altered in disease.

Role of pre-incisional external bilateral ultrasound guide glossopharyngeal nerve block with diluted bupivacaine mixture in pain management in oropharyngeal surgery: A randomized control trial.

The glossopharyngeal nerve block (GNB) was evaluated for pain control together with the magnitude of obtunded gag reflex as a useful clinical sign of GNB. METHODS: 400 patients scheduled for oropharyngeal surgery were randomly allocated into 2 groups (200 patients in each group), Group1 patients received bilateral GNB with 0.125% bupivacaine, 0.5 xylocaine, and 4 mg dexamethasone, while Group 2 patients were enrolled as a control group. Throat pain was evaluated using the visual analog scale at 0.5, 8, and 24 h after surgery, and the degree of gag reflex response was evaluated at the same time points. RESULTS: Postoperative pain scores at rest and during swallowing were significantly lower in Group 1 versus Group 2. The analgesic efficacy of GNB was intensely interrelated with the magnitude of the obtunded gag reflex (P 0.01). CONCLUSIONS: GNB is beneficial for pain control in oropharyngeal surgery. An obtunded gag reflex could be a useful clinical sign for a successful GNB analgesic outcome.

The jugular nerve: A review of this enigmatic structure.

The jugular nerve (JN) is described as joining the superior cervical ganglion to the vagus nerve. It has been studied extensively in many different animal species; however, there is very limited literature about humans. This review delves into various descriptions of this nerve's anatomy and animal studies aimed at deciphering its function. The goal is to shed more light on this understudied structure in humans.

GLOSSOPHARYNGEAL NERVE AS A SOURCE OF OROFACIAL PAIN - DIAGNOSTIC AND THERAPEUTIC CHALLENGES.

Chronic neuropathic orofacial pain along with physical suffering can cause emotional, psychological and social difficulties, which significantly affects the quality of life of patients. Pain in the area of glossopharyngeal nerve innervation, especially chronic neuropathic, is relatively rare, but is significant because of the great suffering it causes to sufferers. It can be life threatening, due to the cardiac arrhythmia, syncope or convulsions it can cause. Drug treatment is often of limited effectiveness and can be fraught with side effects. It is necessary to look for the etiology of the underlying disease, and if possible, to take adequate causal treatment. This review article discusses the etiology, clinical features, differential diagnosis, and treatment modalities of neuropathic pain in the area of glossopharyngeal nerve innervation.

Lower cranial nerve syndromes: a review.

The purpose of this paper is to provide a comprehensive review encompassing the syndromes associated with the lower cranial nerves (LCNs). We will discuss the anatomy of some of these syndromes and the historical contributors after whom they were named. The LCNs can be affected individually or in combination, since the cranial nerves at this level share their courses through the jugular foramen and hypoglossal canal and the extracranial spaces. Numerous alterations affecting them have been described in the literature, but much remains to be discovered on this topic. This paper will highlight some of the subtle differences among these syndromes. Symptoms and signs that have localization value for LCN lesions include impaired speech, deglutition, sensory functions, alterations in taste, autonomic dysfunction, neuralgic pain, dysphagia, head or neck pain, cardiac or gastrointestinal compromise, and weakness of the tongue, trapezius, or sternocleidomastoid muscles. To assess the manifestations of LCN lesions correctly, precise knowledge of the anatomy and physiology of the area is required. Treatments currently used for these conditions will also be addressed here. Effective treatments are available in several such cases, but a precondition for complete recovery is a correct and swift diagnosis.

The pharyngeal plexus: an anatomical review for better understanding postoperative dysphagia.

The pharyngeal plexus is an essential anatomical structure, but the contributions from the glossopharyngeal and vagus nerves and the superior cervical ganglion that give rise to the pharyngeal plexus are not fully understood. The pharyngeal plexus is likely to be encountered during various anterior cervical surgical procedures of the neck such as anterior cervical discectomy and fusion. Therefore, a detailed understanding of its anatomy is essential for the surgeon who operates in and around this region. Although the pharyngeal plexus is an anatomical structure that is widely mentioned in literature and anatomy books, detailed descriptions of its structural nuances are scarce; therefore, we provide a comprehensive review that encompasses all the available data from this critical structure. We conducted a narrative review of the current literature using databases like PubMed, Embase, Ovid, and Cochrane. Information was gathered regarding the pharyngeal plexus to improve our understanding of its anatomy to elucidate its involvement in postoperative spine surgery complications such as dysphagia. The neural contributions of the cranial nerves IX, X, and superior sympathetic ganglion intertwine to form the pharyngeal plexus that can be injured during ACDF procedures. Factors like surgical retraction time, postoperative hematoma, surgical hardware materials, and profiles and smoking are related to postoperative dysphagia onset. Thorough anatomical knowledge and lateral approaches to ACDF are the best preventing measures.

Nerve fiber analysis of the lingual branch of the glossopharyngeal nerve in human adult subjects.

PURPOSE: Fibers of the glossopharyngeal part of the superior constrictor muscle are connected with fibers of the transverse lingual muscle, forming a ring of muscle at the base of the tongue. This group of muscles constrict the midpharyngeal cavity during retrusive movement of the tongue. The purpose of this study is to identify the contribution of the lingual branch of the glossopharyngeal nerve to the neuro-motor control of three muscles: the glossopharyngeal part of the superior pharyngeal constrictor muscle, the palatopharyngeal and the palatoglossus muscles. METHODS: Six en bloc samples (9 sides), including the tissue from the skull base to the hyoid bone were obtained from adult human cadavers. Nerve fiber of the lingual branch of the glossopharyngeal nerve (main root of the glossopharyngeal nerve) was examined by the use of a binocular stereomicroscope. RESULTS: We observed that, after branching to the stylopharyngeal muscle, the lingual branch of the glossopharyngeal nerve branched to the glossopharyngeal part of the superior pharyngeal constrictor muscle, the palatopharyngeal and the palatoglossus muscles before inserting into the space between the muscle layers of the superior and middle pharyngeal constrictors. CONCLUSION: These neuromuscular arrangements may suggest the presence of specialized constrictive movements of the midpharygeal cavity at the level of the base of the tongue with the retrusive movement of the tongue. The simultaneous contraction of the palatopharyngeal and palatoglossus muscles on the pharyngeal stage of deglutition may aid in the passage of bolus from the oral cavity to the midpharyngeal cavity by increasing pharyngeal pressure.

Transection of Gustatory Nerves Differentially Affects Dietary Fat Intake in Obesity-Prone and Obesity-Resistant Rats.

The current prevalence of obesity has been linked to the consumption of highly palatable foods and may be mediated by a dysregulated or hyposensitive orosensory perception of dietary fat, thereby contributing to the susceptibility to develop obesity. The goal of the current study was to investigate the role of lingual taste input in obesity-prone (OP, Osborne-Mendel) and obesity-resistant (OR, S5B/Pl) rats on the consumption of a high-fat diet (HFD). Density of fungiform papillae was assessed as a marker of general orosensory input. To determine if orosensory afferent input mediates dietary fat intake, surgical transection of the chorda tympani and glossopharyngeal nerves (GLX/CTX) was performed in OP and OR rats and HFD caloric intake and body weight were measured. Fungiform papillae density was lower in OP rats, compared with OR rats. GLX/CTX decreased orosensory input in both OP and OR rats, as measured by an increase in the intake of a bitter, quinine solution. Consumption of low-fat diet was not altered by GLX/CTX in OP and OR rats; however, GLX/CTX decreased HFD intake in OR, without altering HFD intake in OP rats. Overall, these data suggest that inhibition of orosensory input in OP rats do not decrease fat intake, thereby supporting that idea that hyposensitive and/or dysregulated orosensory perception of highly palatable foods contribute to the susceptibility to develop obesity.

Randomized Controlled Trial Comparing Landmark and Ultrasound-Guided Glossopharyngeal Nerve in Eagle Syndrome.

INTRODUCTION: The glossopharyngeal nerve lies posterior to the internal carotid artery at the submandibular region. The primary objective of this study was to compare ultrasound-guided glossopharyngeal nerve block (UGPNB) and landmark glossopharyngeal nerve block (GPNB). MATERIALS & METHODS: Inclusion criteria were patients with unilateral Eagle syndrome and ear pain. Group UGPNB (N = 25) received three UGPNBs at weekly intervals with 1.5 mL of 0.5% ropivacaine and 20 mg of methylprednisolone. Group GPNB (N = 26) received landmark GPNB. Pain intensity was evaluated with the numerical rating scale (NRS) before every block, 30 minutes after every block, and at one, three, and five weeks after the third block. Quality of life, assessed using the Brief Pain Inventory (BPI), and satisfaction scores were noted. RESULTS: NRS scores before the second and third blocks and a week after were significantly lower in group UGPNB and comparable at weeks 3 and 5. NRS scores 30 minutes after every block were significantly decreased from the preblock values but were comparable between groups. In 68% of patients, a curvilinear probe delineated the internal carotid artery (ICA). Out-of-plane needle trajectory was required in 64% of patients. BPI and satisfaction scores were significantly better in the UGPNB group in the "block" weeks. CONCLUSIONS: UGPNB with 1.5 mL of 0.5% ropivacaine and 20 mg of methylprednisolone injected posterior to the ICA in the submandibular region provides better pain relief for at least a week compared with an extraoral landmark technique when three weekly consecutive blocks are given. In most patients, a curvilinear probe and out-of-plane needle trajectory are most suitable for ultrasound block.

Microvascular Decompression Alone without Rhizotomy Is an Effective Way of Treating Glossopharyngeal Neuralgia: Clinical Analysis of 46 Cases.

BACKGROUND: Microvascular decompression (MVD) has been the right choice for glossopharyngeal neuralgia (GPN) patients. However, whether glossopharyngeal/vagal nerve root rhizotomy should be combined with MVD is still controversial. OBJECTIVE: To evaluate whether glossopharyngeal/vagal nerve root rhizotomy during MVD is necessary for the treatment of GPN. METHODS: We performed a retrospective study of 46 GPN patients who underwent MVD surgery alone in our hospital, and their patient demographics, clinical presentations, and intraoperative findings are shown. The immediate and long-term follow-up outcomes were investigated to show the treatment's efficiency and safety; the outcome was also compared with our previous study. The relevant literature was reviewed to show complications for GPN patients undergoing glossopharyngeal/vagal nerve root rhizotomy with MVD. RESULTS: The most common offending vessel was the posterior inferior cerebellar artery (60.9%). 100% of the patients were pain-free (score of I on the Barrow Neurological Institute pain intensity [BNI-P] scale) immediately after MVD surgery, while 1 patient relapsed with occasional pain 12 months after the operation (score of III on the BNI-P scale). Poor wound healing and hearing loss were found in 1 case each. No complications related to the glossopharyngeal nerve/vagal nerve were reported. Some surgical techniques, such as thorough exploration of the CN IX-X rootlets, full freeing from arachnoid adhesions, and usage of a moist gelatin sponge, can improve the success rate of the operation. CONCLUSIONS: MVD alone without rhizotomy is an effective and safe method for patients with GPN.

First definition of burned choroid plexus in acidic cerebrospinal fluid-filled brain ventricles during subarachnoid hemorrhage: Experimental study.

Blood and cerebrospinal fluid (CSF) acidosis is the most troubling complication in subarachnoid hemorrhage (SAH) if carotid body (CB) networks are disrupted. However, histopathological examination of the choroid plexus (CP) in acidic CSF has not been evaluated so far. In this study, we aimed to investigate the CP in acidic CSF following SAH. Twenty-eight rabbits were used. Five rabbits were used to analyze CB network (control group; n = 5); seven rabbits were injected 1 mL of saline (Sham group; n = 7); and the rest 16 rabbits were given 1 mL of autologous arterial blood inject into the cisterna magna to create SAH (SAH group; n = 16). Blood and CSF pH values were recorded before/during/after the experimental procedures. Nuclear darkening, cellular shrinkage and pyknosis suggested the presence of apoptosis of epithelial cells of CP. The densities of normal and degenerated epithelial cells of CPs were estimated using stereological methods. The relationship between the pH values and degenerated epithelial cell densities of CPs were statistically compared by Mann-Whitney U-test. The pH values of blood were estimated as 7.359 ± 0.039 in the control group, 7.318 ± 0.062 in the Sham group, 7.23 ± 0.013 in the SAH group. CSF pH values were 7.313 ± 0.028 in the control group, 7.296 ± 0.045 in the Sham group, and 7.224 ± 0.012 in the SAH group. Degenerated epithelial cell density of CP was 25 ± 7 in the control group, 226 ± 64 in the Sham group, and 2115 ± 635 in the SAH group. There was a considerable link between CSF pH values and degenerated epithelial cells of CP (P < 0.0001). This study shows that CB insult causes acidosis of CSF as well as cellular degeneration of CP during SAH. This is the first description of this in the literature.

A Case of Isolated Unilateral Glossopharyngeal Nerve Palsy.

Isolated palsy of the glossopharyngeal nerve is rare. We report the case of an elderly patient with unilateral right glossopharyngeal nerve palsy secondary to extra cranial ischemia. On examination there was no other deficit other than an absent right gag reflex. She was diagnosed clinically with ischemic stroke of the ninth nerve, and her daily dose of aspirin was increased from 81 mg to 325 mg. Magnetic resonance imaging of the brain showed a normal brainstem and cerebellum with patent intracranial circulation. Total resolution of the paralysis was seen 2 months later. The possible mechanisms suspected were diabetic or hypertensive stenosis of the vasa nervorum or compression of the ninth nerve by an internal carotid artery dissection or aneurysm. This article discusses the various etiologies and mechanisms of this rare condition. It is unique because of the nerve's location and relationship to other structures.

Ultrasound-Guided Glossopharyngeal Nerve Block at Pharyngeal Wall Level in a Patient with Carcinoma Tongue.

Glossopharyngeal nerve (GPN) block is used for pain management in patients' head and neck malignancy. The GPN is a mixed nerve containing both motor and sensory fibers. The usual approaches for GPN blocks are usually topical, intraoral, or peristyloid. Topical anesthesia may be difficult in patients with limited mouth opening or when there is inflammation in the area of interest. Intraoral and peristyloid approaches have risk of inadvertent neurovascular injection. The intraoral technique may lead to long-lasting oropharyngeal discomfort. Hence, GPN block is done at the pharyngeal wall level for pain relief.

Defining the Anatomy of the Vagus Nerve and Its Clinical Relevance for the Neurosurgical Treatment of Glossopharyngeal Neuralgia.

The neurosurgical treatment of glossopharyngeal neuralgia includes microvascular decompression or rhizotomy of the nerve. When considering open section of the glossopharyngeal nerve, numerous authors have recommended additional sectioning of the 'upper rootlets' of the vagus nerve because these fibers can occasionally carry the pain fibers causing the patient's symptoms. Sacrifice of vagus nerve rootlets, however, carries the potential risk of dysphagia and dysphonia. In this study, the anatomy and physiology of the vagus nerve rootlets are characterized to provide guidance for surgical decision-making. Twelve patients who underwent posterior fossa craniotomy with intraoperative electrophysiological monitoring of the vagus nerve rootlets were included in this study. In the 7 patients with glossopharyngeal neuralgia, the clinical outcomes and complications were further analyzed. In half of the patients, electrophysiological data demonstrated pure sensory function in the rostral rootlet(s) of the vagus nerve and motor responses in its caudal rootlets. This orientation of the vagus nerve, with some pure sensory function in its most rostral rootlet(s), was defined as Type A. In the other half of patients, all vagus nerve rootlets (including the most rostral) had motor responses. This was defined as Type B. The surgical strategy was guided by whether the patient had a Type A or Type B vagus nerve. For those with Type B, no vagus nerve rootlets were sacrificed. None of the patients with glossopharyngeal neuralgia developed any permanent neurological deficits. We recommend intraoperative electrophysiological testing of the vagus nerve rootlets. If the testing reveals motor innervation in the rostral vagal rootlet (Type B), that rootlet may be decompressed but should not be sectioned to avoid a motor complication. Patients with pure sensory innervation of the rostral rootlet(s) (Type A) can have decompression or section of those rootlets without complication.

Toward understanding the causes of blood pH irregularities and the roles of newly described binuclear neurons of carotid bodies on blood pH regulation during subarachnoid hemorrhage: Experimental study.

Acidosis is the most dangerous complication of subarachnoid hemorrhage (SAH). Although the carotid bodies (CBs) network is essential for pH regulation, neither binuclear neurons (BNN) nor their functions have been mentioned so far in the literature. The aim of this study was to investigate the crucial roles of mononuclear (MNN) or BNN in CBs on acidosis following SAH. Twenty-five hybrid rabbits were used. Five rabbits were used as a control group, six for sham, and the remaining 14 rabbits were used as the study group by injection of 1 mL of autologous arterial blood into the cisterna magna to produce SAH. Normal and degenerated MNN/BNN densities of CBs were counted by stereological methods. The mean blood pH values were: 7.362 ± 0.041 in the control group; 7.324 ± 0.064 in sham, 7.272 ± 0.062 in the SAH group. The degenerated MNN and BNN values were 5 ± 1/mm3 and 9 ± 3/mm3 in the control group; 15 ± 5/mm3 and 22 ± 6/mm3 in sham, 965 ± 113/mm3 and 1532 ± 176/mm3 in the SAH group. Mean pH values were under 7.212 ± 0.130 in animals with prominent degenerated BNN. The differences between MNN/pH changes were significant between the SAH and control groups (P < 0.005); whereas BNN/pH values were significant between the SAH and sham groups (pH < 0.005), SAH and control (P < 0.0001). BNN degeneration could result in more severe acidosis than MNN following SAH which has not been described so far.