Rare case of divided phrenic nerve variation: a cadaveric case report

The phrenic nerve innervates the respiratory diaphragm, the primary muscle active during ventilation. The canonical path of the phrenic nerve originates from the cervical spine at C3-C5 spinal nerves and travels inferiorly through the neck and thoracic cavity to reach the diaphragm. During a cadaver dissection, a variation of the phrenic nerve was discovered in a 93-year-old male specimen. A traditional origin of the phrenic nerve was noted; however, the nerve branched into medial and lateral components at the level of the superior trunk of the brachial plexus. The branches reconnected at the apex of the aortic arch and continued inferiorly to innervate the ipsilateral diaphragm. This case study describes a rare type of branching of the phrenic nerve and explores its potential impact on clinical procedures.

Proposal for Manual Osteopathic Treatment of the Phrenic Nerve

The article reviews the anatomical path of the phrenic nerve and its anastomoses, with the most up-to-date knowledge reported in the literature. We have briefly reviewed the possible phrenic dysfunctions, with the final aim of presenting an osteopathic manual approach for the treatment of the most superficial portion of the nerve, using a gentle technique. The approach we propose is, therefore, a theory based on clinical experience and the rationale that we can extrapolate from the literature. We hope that the article will be a stimulus for further experimental investigations using the technique illustrated in the article. To the authors' knowledge, this is the first article that takes into consideration the hypothesis of an osteopathic treatment with gentle techniques for the phrenic nerve.

Effect of local anesthetic volume (20 vs. 40 ml) on the analgesic efficacy of costoclavicular block in arthroscopic shoulder surgery: a randomized controlled trial

BACKGROUND

Among the various diaphragm-sparing alternatives to interscalene block, costoclavicular block (CCB) demonstrated a low hemidiaphragmatic paresis (HDP) occurrence but an inconsistent analgesic effect in arthroscopic shoulder surgery. We hypothesized that a larger volume of local anesthetic for CCB could provide sufficient analgesia by achieving sufficient supraclavicular spreading.

METHODS

Sixty patients scheduled for arthroscopic rotator cuff repair were randomly assigned to receive CCB using one of two volumes of local anesthetic (CCB20, 0.75% ropivacaine 20 ml; CCB40, 0.375% ropivacaine 40 ml). The primary outcome was the rate of complete analgesia (0 on the numeric rating scale of pain) at 1 h postoperatively. The secondary outcomes included a sonographic assessment of local anesthetic spread, diaphragmatic function, pulmonary function, postoperative opioid use, and other pain-related experiences within 24 h postoperatively.

RESULTS

The rates of complete analgesia were not significantly different (23.3% [7/30] and 33.3% [10/30] in the CCB20 and CCB40 groups, respectively; risk difference 10%, 95% CI [-13, 32], P = 0.567). There were no significant differences in other pain-related outcomes. Among the clinical factors considered, the only factor significantly associated with postoperative pain was the sonographic observation of supraclavicular spreading. There were no significant differences in the incidence of HDP and the change in pulmonary function between the two groups.

CONCLUSIONS

Using 40 ml of local anesthetic does not guarantee supraclavicular spread during CCB. Moreover, it does not result in a higher rate of complete analgesia compared to using 20 ml of local anesthetic in arthroscopic shoulder surgery.

Phrenic Nerve Transfer to Musculocutaneous Nerve: An Anatomical and Histological Study

BACKGROUND

To restore elbow flexor muscle function in case of traumatic brachial plexus avulsion, the phrenic nerve transfer to the musculocutaneous nerve has become part of clinical practice. The nerve transfer can be done by means of video-assisted thoracic surgery without nerve graft or via supraclavicular approach in combination with an autograft. This study focuses on a detailed microscopic and macroscopic examination of the phrenic nerve. It will allow a better interpretation of existing clinical results and, thus, serve as a basis for future clinical studies.

MATERIAL AND METHODS

An anatomical study was conducted on 28 body donors of Caucasian origin (female n = 14, male n = 14). A sliding caliper and measuring tape were used to measure the diameter and length of the nerves. Sudan black staining was performed on 15 µm thick cryostat sections mounted on glass slides and the number of axons was determined by the ImageJ counting tool. In 23 individuals, the phrenic nerve could be examined on both sides. In 5 individuals, however, only one side was examined. Thus, a total of 51 nerves were examined.

RESULTS

The mean length of the left phrenic nerves (33 cm (29-38 cm)) was significantly longer compared to the mean length of the right phrenic nerves (30 cm (24-33 cm)) (p < 0.001). Accessory phrenic nerves were present in 9 of 51 (18%) phrenic nerves. The mean number of phrenic nerves axons at the level of the first intercostal space in body donors with a right accessory phrenic nerve was significantly greater compared to the mean number of phrenic nerves axons at the same level in body donors without a right accessory phrenic nerve (3145 (range, 2688-3877) vs. 2278 (range, 1558-3276)), p = 0.034. A negative correlation was registered between age and the nerve number of axons in left (0.742, p < 0.001) and right (-0.273, p = 0.197) phrenic nerves. The mean distance from the upper edge of the ventral ramus of the fourth cervical spinal nerve to the point of entrance of the musculocutaneous nerve between the two parts of the coracobrachialis muscle was 19 cm (range, 15-24 cm) for the right and 20 cm (range, 15-25 cm) for the left arm.

CONCLUSIONS

If an accessory phrenic nerve is available, it presumably should be spared. Thus, in that case, a supraclavicular approach in combination with a nerve graft would probably be of advantage.

Combined Intermediate Cervical Plexus and Costoclavicular Block for Arthroscopic Shoulder Surgery: A Prospective Feasibility Study

A combined cervical plexus and costoclavicular block provides effective shoulder analgesia without the risk of hemidiaphragmatic paralysis. However, whether this technique can also provide effective anesthesia for shoulder surgery remains unknown. Therefore, this study aimed to assess the feasibility and adverse effects of combined blocks in arthroscopic shoulder surgery. Fifty patients scheduled for arthroscopic shoulder surgery were prospectively enrolled. Intermediate cervical plexus (5 mL of 0.5% ropivacaine) and costoclavicular (20 mL of 0.5% ropivacaine) blocks were administered under ultrasound guidance. The block procedure time, needle pass, patient discomfort, anesthesia quality, onset time, postoperative analgesia quality, adverse events, and patient satisfaction were assessed. Surgical and block success were achieved in 45 (90%; 95% confidence interval [CI], 78-97%) and 44 (88%; 95% CI, 76-95%) patients, respectively. Three patients required local anesthetic supplementation, and two required general anesthesia. The incidence of hemidiaphragmatic paralysis was 12.0% (95% CI, 4.5-24.3%). Postoperative pain control was effective for the first 24 h postoperative. Neurological deficits were not observed. The patients reported a high level of satisfaction. This study revealed that a combined cervical plexus and costoclavicular block provided effective surgical anesthesia for arthroscopic shoulder surgery with a 12% incidence of hemidiaphragmatic paralysis. Further randomized studies comparing this technique with interscalene block are required.

Could C3, 4, and 5 Nerve Root Block be a Better Alternative to Interscalene Block Plus Intermediate Cervical Plexus Block for Patients Undergoing Surgery for Midshaft and Medial Clavicle Fractures? A Randomized Controlled Trial

BACKGROUND

Variable innervation of the clavicle is a major challenge in surgery of clavicle fractures with patients under regional anesthesia. An interscalene block (ISB) combined with an intermediate cervical plexus block (ICPB) provides analgesia in clavicle fracture surgery, but this combination does not completely block sensation in the midshaft or medial clavicle. Cervical nerve root block is an alternative to deep cervical plexus block and has recently been used as an analgesic method in the neck and shoulder. Whether it should be used as an alternative for midshaft and medial clavicle fractures is unknown.

QUESTIONS/PURPOSES

In this randomized controlled trial, we compared a C3, 4, and 5 nerve root block to ISB combined with ICPB in surgery of midshaft and medial clavicle fractures in terms of the (1) proportion of patients achieving a sensory block that is sufficient for surgery, (2) onset time and duration of the block, and (3) effectiveness of postoperative analgesia, as measured by pain scores and consumption of analgesics.

METHODS

Between November 2021 and December 2021, we treated 154 patients for clavicle fractures. A total of 122 were potentially eligible, 91 of whom agreed to participate in this study. Twenty-nine patients were excluded because the patients chose general anesthesia or declined to undergo surgery. Ultimately, 62 patients were randomly allocated into the C3, 4, and 5 group or ISB + ICPB group, with 31 patients in each group; there were no dropouts. All patients were analyzed in the group they were randomized to under intention-to-treat principles. The assessor and patients were blinded to randomization throughout the trial. The two groups did not differ in any important ways, including age, gender, BMI, American Society of Anesthesiologists classification, and type of clavicle fracture. The two groups received either an ultrasound-guided C3, 4, and 5 nerve root block with 2, 3, and 5 mL of 0.5% ropivacaine or ultrasound-guided ISB with ICPB with 20 mL of 0.5% ropivacaine. The primary outcome was the proportion of patients in each group with a successful nerveba block who did not receive general anesthesia; this was defined as nerve block success. Secondary outcomes included the onset time and duration of the sensory block, defined as the onset to the moment when the patients felt pain and sought rescue analgesia; pain assessment in terms of the numeric rating scale (NRS) score (range 0 to 10) for pain after nerve block before and during surgery; and the median amount of sufentanil consumed intraoperatively and postoperatively in the recovery room. The dosing of sufentanil was determined by the assessor when the NRS score was 1 to 3 points. If the NRS score was more than 3 points, general anesthesia was administered as a rescue method. Complications after the two inventions such as toxic reaction, dyspnea, hoarseness, pneumothorax, and Horner syndrome were also recorded in this study.

RESULTS

A higher proportion of patients in the C3, 4, and 5 group had a successful nerve block than in the ISB + ICPB group (97% [30 of 31] versus 68% [21 of 31], risk ratio 6 [95% CI 1.5 to 37]; p < 0.01). The median onset time was 2.5 minutes (range 2.0 to 3.0 minutes) in the C3, 4, and 5 group and 12 minutes (range 9 to 16 minutes) in the ISB + ICPB group (difference of medians 10 minutes; p < 0.001). The sensory block duration was 10 ± 2 hours in the C3, 4, and 5 group and 8 ± 2 hours in the ISB + ICPB group (mean difference 2 hours [95% CI 1 to 3 hours]; p < 0.001). The median sufentanil consumption was lower in the C3, 4, 5 group than in the ISB + ICPB (median 5 µg [range 0.0 to 5.0 µg] versus median 0 µg [range 0.0 to 0.0 µg]; difference of medians 5.0 µg; p < 0.001). There were no differences between the two groups regarding NRS scores after nerve blocks and NRS score for incision and periosteum separation, with the minimum clinically important difference set at a 2-point difference (of 10). There were no severe complications in this study.

CONCLUSION

Based on our analysis of the data, a C3, 4, and 5 nerve root block was better than ISB combined with ICPB for surgery to treat medial shaft and medial clavicle fractures. When choosing the anesthesia method, however, the patient's basic physiologic condition and possible complications should be considered.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Ultrasound-Guided Phrenic Nerve Block for Lung Nodule Biopsy: Single-Center Initial Experience

RATIONALE AND OBJECTIVES

Biopsy of lung nodules in the lower lung fields can be difficult because of breathing motion. Ipsilateral phrenic nerve block (PNB) before biopsy should make the biopsy safer, easier, and more precisely targeted. We describe the use of ultrasound-guided PNB before lung nodule biopsy, including relevant anatomy and variations, complications, and technique, along with our first 40 cases.

MATERIALS AND METHODS

We retrospectively reviewed patients who underwent PNB before computed tomography (CT)- or ultrasound-guided lung nodule biopsy from April 2015 through March 2020. Patient demographics, CT fluoroscopy time, radiation dose, complications, diagnostic yield, and effectiveness of PNB were recorded. Effectiveness of PNB was based on direct observation of diaphragmatic motion. Control group data for biopsies during the same time frame were collected and matched with nodules ≤1 cm from the PNB group.

RESULTS

Among 40 patients identified, no complications occurred related to the PNB. Mean (SD) nodule size was 12.4 (6.2) mm. True-positive results were obtained in 39 patients (98%), with 1 false-negative after an ineffective PNB. PNB was effective in 70%. When CT fluoroscopy was used for the biopsy, radiation dose was significantly lower after an effective PNB than an ineffective PNB (p < .001). Effective PNB was significantly more common with injection of ≥4 mL of local anesthetic (p = .01). Comparison with 19 matched controls showed significantly fewer instances of pneumothorax (p = .02) and greater diagnostic success (p = .03) for the PNB group.

CONCLUSION

Ultrasound-guided PNB is safe and effective and can improve outcomes when used before lung nodule biopsy.

The Critical Appraisal Tool for Anatomical Meta-analysis (CATAM): A framework for critically appraising anatomical meta-analyses

The hallmark of evidence-based medicine is the meta-analysis (MA). For much of its rich history, the field of anatomy has been dominated by descriptive, cadaveric studies. In the last two decades, quantitative measurements and statistical analyses have frequently accompanied such studies. These studies have directly led to the publication of anatomical MAs, which have ushered in the exciting field of evidence-based anatomy. Although critical appraisal tools exist for clinical MAs, none of them are specifically tailored for anatomical MAs. Therefore, the purpose of this paper is to provide a framework by which clinical anatomists and others can critically appraise anatomical MAs using the Critical Appraisal Tool for Anatomical Meta-analysis (CATAM). Using a running example from a recently published MA, we show how to use the CATAM rubric in a step-by-step fashion. Each scored section of the CATAM rubric is summated into a total score (maximum 50 points). This score is then referenced to a conversion chart, which assigns a qualitative value to the MA in a range from "very good" to "poor." Future studies can investigate the interrater reliability of the instrument, and possibly subject the CATAM rubric to a Delphi panel. As anatomical MAs become more commonplace at surgical grand rounds and journal clubs in academic medical centers throughout the world, we hope that the CATAM rubric can help facilitate meaningful discussions about the quality and clinical relevance of anatomical MAs. This article is protected by copyright. All rights reserved.

Phrenic Nerve Stimulator Placement via the Cervical Approach: Technique and Anatomic Considerations

BACKGROUND

Diaphragmatic pacing via phrenic nerve stimulation can help improve breathing and facilitate mechanical ventilation weaning in patients with respiratory failure secondary to brainstem injury, high cervical spinal cord injury, or congenital central hypoventilation. Devices can be placed utilizing several techniques; however, nuances regarding placement are not well published.

OBJECTIVE

To describe our experience with phrenic nerve stimulator placement via the cervical approach with a focus on surgical anatomy, variations, and technique.

METHODS

Placement of phrenic nerve stimulator via a cervical approach is described in detail.

RESULTS

Successful placement of phrenic nerve stimulator without complication.

CONCLUSION

The cervical approach for the placement of a phrenic nerve stimulator is a safe and effective option for patients. Detailed knowledge of anatomy and anatomic variations is required. Potential advantages and disadvantages are discussed.

Can saline injection protect phrenic nerve? - A randomised controlled study

Background and Aims

Various methods were attempted to reduce the incidence of phrenic nerve palsy during interscalene brachial plexus nerve block. Mechanism of phrenic palsy was presumed to be due to the spread of local anaesthetic anterior to the anterior scalene muscle. We hypothesised that by injecting saline in this anatomical location prior to performing an interscalene block might reduce the incidence of phrenic palsy.

Methods

This was a double-blinded randomised controlled study performed in a single-centre, university-teaching hospital. A total of 36 patients were randomised to either group C (conventional group) or group S (saline group). Ultrasound-guided interscalene block was administered with 20 ml of 0.25% levo-bupivacaine in both groups. Ten ml of normal saline was injected anterior to anterior scalene muscle in group S prior to performing interscalene block. A blinded radiologist performed diaphragmatic ultrasound pre- and post-operatively to document phrenic palsy. Bedside spirometry was used to perform baseline and post-operative pulmonary function test. The primary outcome was to look at the incidence of phrenic palsy as measured by diaphragmatic palsy on ultrasound performed by radiologist. Statistical Package for the Social Sciences (SPSS) version 25 was used for statistical analysis.

Results

Significantly less patients in the saline group developed diaphragmatic paresis when compared to conventional group (44% vs. 94%, Chi-squared = 10.01, P = 0.002). There was no difference in post-operative pain, subjective sensation of dyspnoea or patient satisfaction between the groups.

Conclusion

Injecting saline anterior to anterior scalene muscle reduces the incidence of diaphragmatic palsy when performing interscalene block.

Effects of Local Anesthetic Volume (Standard Versus Low) on Incidence of Hemidiaphragmatic Paralysis and Analgesic Quality for Ultrasound-Guided Superior Trunk Block After Arthroscopic Shoulder Surgery

BACKGROUND

Relative to interscalene block, superior trunk block (STB) provides comparable analgesia and a reduced risk of hemidiaphragmatic paralysis. However, the incidence of hemidiaphragmatic paralysis remains high when a standard volume (15 mL) of local anesthetic is used. This study aimed to evaluate the effects of local anesthetic volume of STB on the incidence of phrenic nerve palsy, as well as its analgesic efficacy following arthroscopic shoulder surgery.

METHODS

Patients scheduled for elective arthroscopic shoulder surgery were randomized to receive ultrasound-guided STB using either 5- or 15-mL 0.5% ropivacaine before general anesthesia. The primary outcome was the incidence of hemidiaphragmatic paralysis at 30 minutes after block. The secondary outcomes were pulmonary function, grade of sensory and motor blockade, pain score, opioid consumption, adverse effects, and satisfaction.

RESULTS

Relative to standard-volume STB, low-volume STB was associated with a lower incidence of hemidiaphragmatic paralysis after block (14.3 [4.8%-30.3%] vs 65.7 [46.8%-80.9%]; difference 51.4% [95% confidence intervals {CIs}, 29.0%-67.1%]; P < .0001) and at the postanesthesia care unit (9.4% vs 50.0%; difference 40.6 [95% CI, 18.9%-57.7%]; P = .0004). Pulmonary function was also better preserved in the low-volume group than in the standard-volume group. The extent of the sensory and motor blocks was significantly different between the groups. Pain-related outcomes, satisfaction, and any adverse events were not significantly different between the groups.

CONCLUSIONS

Low-volume STB provided a lower incidence of hemidiaphragmatic paralysis with no significant difference in analgesic efficacy relative to standard-volume STB for arthroscopic shoulder surgery.

A meta-analysis on the anatomical variability of the brachial plexus: Part II - Branching of the supraclavicular part

INTRODUCTION

The anatomy of the supraclavicular part of the brachial plexus is highly variable, therefore the aim of this study was to perform a systematic review and meta-analysis of the various origins of the long thoracic, dorsal scapular, suprascapular and subclavian nerves.

MATERIALS AND METHODS

Major electronic databases were searched to identify all cadaveric studies investigating the morphology of the supraclavicular part of the brachial plexus. Data on the origins of these nerves were extracted and classified. A random effects meta-analysis was performed to state the pooled prevalence estimates.

RESULTS

A total of 26 studies, constituting a total of 1021 cases, were deemed eligible for inclusion into the meta-analysis. The usual origin of the long thoracic nerve from the C5, C6 and C7 roots was observed in 78.1% (95% CI 69.4-86.7%) of cases and 21.9% (95% CI 13.3-30.6%) had unusual origins. An accessory long thoracic nerve occurred in 0.3% (95% CI 0-0.7%) of cases. The overall prevalence of the dorsal scapular nerve arising from its usual origin the C5 root was found in 85.2% (95% CI 75.7-94.6%) of cases, while 14.8% (95% CI 5.4-24.3%) appeared abnormal. The suprascapular nerve emerged from its usual point on the superior trunk in 89.8% (95% CI 85.1-94.4%) of cases and in 10.2% (95% CI 5.6-14.9%) of cases had a variable origin. An accessory suprascapular nerve was present in 0.2% (95% CI 0-0.6%). Two possible sites of origin of the subclavian nerve were noted and the typical origin from the superior trunk was found in 98.3% (95% CI 96.3-100%) of cases and variable origin from the C5 root in 1.7% (95% CI 0-3.7%). All unusual origins of each nerve were much less common.

CONCLUSIONS

The nerves emerging from the supraclavicular part of the brachial plexus express a wide spectrum of potential origins. Based on their various origins, a new classification system for all the nerves belonging to the supraclavicular part was proposed. Knowledge of these variations and their prevalence data is important to prevent iatrogenic injuries and to state useful landmarks for interventions in the axilla.

Right hemidiaphragmatic paralysis after cervical transforaminal epidural steroid injection: illustrative case

BACKGROUND

Cervical radiculopathy is a common cause of neck pain, with radiation into the upper extremity in a dermatomal pattern. Corticosteroid injection is a conservative management option with a low risk of major adverse events. No reviewed literature or case reports have implicated phrenic nerve injury secondary to cervical transforaminal epidural steroid injection (CTFESI).

OBSERVATIONS

A 45-year-old man with severe right C6 radiculopathy secondary to a large right-sided C5–6 herniated intervertebral disc presented to the pain management clinic, where he received a right-sided C6 CTFESI. An hour after injection, the patient experienced shortness of breath, which was found to be caused by right diaphragmatic paralysis. The patient underwent a C5–6 anterior cervical discectomy and fusion, which provided complete relief of his radicular symptoms. However, the right hemidiaphragmatic paralysis remained at the 1-year postoperative visit.

LESSONS

Thorough literature review showed no established explanations for phrenic nerve injury after CTFESI. In this study, the authors explored the suspected mechanisms of possible injury to the phrenic nerve. Epidural corticosteroid injection is considered to be a safe option for conservative management of cervical radiculopathy. This study unveiled a unique and important adverse event that should be considered before a patient receives CTFESI.

Phrenic nerve neurotization utilizing half of the spinal accessory nerve to the functional restoration of the paralyzed diaphragm in high spinal cord injury secondary to brain tumor resection

The authors present a case of functional improvement of diaphragmatic paralysis in high spinal cord injury, performing a neurotization of the phrenic nerve with accessory spinal nerve hemisection. A C1-C2 injury of the spinal cord was diagnosed in a 12-year-old male, secondary to resection of a brainstem glioma. The patient did not have diaphragmatic motility at the moment that the mechanical ventilation was removed; however, he presented apnea. The patient underwent neurotization of the right phrenic nerve with the right spinal accessory nerve, 5 months after the injury and 6 months after nerve transfer; he had complete mobilization of the right hemidiaphragm, nevertheless persisted with paralysis of the left hemidiaphragm. This achievement reduced the use of mechanical ventilation during the day.

Anatomic Variation of the Phrenic Nerve and Brachial Plexus Encountered during 100 Supraclavicular Decompressions for Neurogenic Thoracic Outlet Syndrome with Associated Postoperative Neurologic Complications

BACKGROUND

The objective of this study was to characterize phrenic nerve and brachial plexus variation encountered during supraclavicular decompression for neurogenic thoracic outlet syndrome and to identify associated postoperative neurologic complications.

METHODS

A multicenter retrospective review was performed to evaluate anatomic variation of the phrenic nerve and brachial plexus from November 2010 to July 2018. After initial characterization, the following two groups were identified: variant anatomy (VA) group and standard anatomy (SA) group. Complications were analyzed and compared between the two groups.

RESULTS

In total, 105 patients were identified, and 100 patients met inclusion criteria. Any anatomic variation of the standard course or configuration of the phrenic nerve and/or brachial plexus was encountered in 47 (47%) patients. Phrenic nerve anatomic variations were identified in 28 (28%) patients. These included 9 duplicated nerves, 6 lateral accessory nerves, 8 medial displacement, and 5 lateral displacement. Brachial plexus anatomic variation was found in 34 (34%) patients. The most common variant configuration of a fused middle and inferior trunk was identified in 25 (25%) patients. Combined phrenic nerve and brachial plexus anatomic variation was demonstrated in 15 (15%) patients. The VA and SA groups consisted of 47 and 53 patients, respectively. Transient phrenic nerve injury with postoperative elevation of the ipsilateral hemidiaphragm was documented in 3 (6.4%) patients in the VA group and 6 (11.3%) patients in the SA group (P = 0.49). Permanent phrenic nerve injury was identified in 1 (2.1%) patient in the VA group (P = 0.47) and none in the SA group. Transient brachial plexopathy was encountered in 1 (1.9%) patient in the SA group (P = 1.0) with full recovery to normal function.

CONCLUSIONS

Anatomic variability of the phrenic nerve and brachial plexus are encountered more frequently than previously reported. While the incidence of nerve injury is low, surgeons operating within the thoracic aperture should be familiar with variant anatomy to reduce postoperative complications.

Triangles of the neck: a review with clinical/surgical applications

The neck is a geometric region that can be studied and operated using anatomical triangles. There are many triangles of the neck, which can be useful landmarks for the surgeon. A better understanding of these triangles make surgery more efficient and avoid intraoperative complications. Herein, we provide a comprehensive review of the triangles of the neck and their clinical and surgical applications.

Congenital central hypoventilation syndrome: An overview of etiopathogenesis, associated pathologies, clinical presentation, and management

Congenital central hypoventilation syndrome (CCHS), known colloquially as Ondine's curse, is a rare disorder characterized by impaired autonomic control of breathing during sleep from the loss of vagal input and diminished sensitivity of CO₂ receptors in the medulla. CCHS correlates to the malformation of the neural crest located in the brainstem; this consequently affects the loss of sensitivity of CO₂ chemoreceptors, bringing about hypoventilation during sleep. The primary cause of CCHS is the mutation of the paired-like homeobox PHO2XB gene, found in 90% of the patients. This mutation not only affects breathing but also drives neurological abnormalities such as autonomic and neurocognitive dysfunction. Though typically congenital, there have been late-onset (i.e., acquired) cases reported. It is vital for physicians and clinicians to be able to diagnose CCHS due to its similar presentation to other syndromes and disorders, which may cause it to be misdiagnosed and may account for its deleterious effects. CCHS can lead to a constellation of symptoms, and consideration of diseases that present concomitantly with CCHS affords us a better understanding of the etiology of this illness. Although a rare syndrome, we aim to review the current literature to emphasize the pathogenesis, etiology, clinical presentation, symptoms, diagnosis, and current treatment methods of CCHS for clinicians to better identify and understand this condition.