後縦靱帯骨化症

Objective: To evaluate the agreement between cervical magnetic resonance imaging (MRI) parameters measured by the Cervi-AI model and expert assessments, and to investigate the association between these parameters and the selection of anterior or posterior surgical approaches in patients with multilevel degenerative cervical myelopathy (DCM). Methods: This retrospective study included patients with DCM who underwent cervical spine surgery at the Second Affiliated Hospital of Naval Medical University between June 2023 and October 2024. Patients were categorized into anterior and posterior surgical approach groups according to the actual surgical procedure performed. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were used to compare the consistency of cervical spinal stenosis (CSS) grade, involved segments, and maximum spinal cord compression (MSCC) index assessed by Cervi-AI with the expert-measured reference standard. Multivariable logistic regression analysis was performed to identify factors associated with surgical approach selection. Receiver operating characteristic (ROC) curves were generated, and the area under the curve (AUC) was calculated to evaluate the predictive performance of clinical and imaging parameters for surgical approach selection. Results: A total of 146 patients were included (77 males and 69 females), with a mean age of (52.0±12.0) years. Eighty-six patients underwent anterior surgery, and 60 underwent posterior surgery. No significant differences were observed between the two groups in terms of symptom type or symptom duration (all P values>0.05). Cervi-AI measurements showed excellent agreement with expert assessments for the number of involved CSS levels, maximum stenosis grade, and MSCC index, with ICCs of 0.970, 0.958, and 0.984, respectively. Multivariable logistic regression analysis revealed that longer symptom duration (per 12-month increase: OR=0.752, 95%CI: 0.576-0.957, P=0.020), a greater number of involved CSS levels (per additional level: OR=0.058, 95%CI: 0.014-0.162, P<0.001), and the presence of ossification of the posterior longitudinal ligament (OPLL) (OR=0.103, 95%CI: 0.027-0.328, P<0.001) were independently associated with selecting an posterior surgical approach. ROC curve analysis demonstrated that the number of involved CSS levels had the highest predictive performance for surgical approach selection (AUC=0.903, 95%CI: 0.852-0.955, P<0.001). Conclusions: The Cervi-AI model can provide highly consistent and standardized measurements of key cervical MRI parameters compared with expert assessments. Symptom duration, the extent of cervical spinal stenosis, and the presence of OPLL are independently associated with the selection of anterior versus posterior surgical approaches in patients with multilevel DCM.

Autosomal recessive hypophosphatemic rickets type 2 (ARHR2) is a rare metabolic bone disorder caused by biallelic loss-of-function variants in ENPP1, the gene encoding for Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), an enzyme essential for generating extracellular pyrophosphate, a key endogenous inhibitor of ectopic calcification. The clinical spectrum of ENPP1 deficiency varies widely, and recognition in adulthood is challenging due to phenotypic heterogeneity and overlap with more common metabolic bone and parathyroid disorders. We describe two brothers in their late 40s with a novel homozygous ENPP1 splice-site pathogenic variant (c.1437 + 1G > C) presenting with chronic hypophosphatemia, elevated serum PTH, extra-skeletal calcifications, and markedly abnormal bone microarchitecture on high-resolution peripheral quantitative computed tomography (HR-pQCT). Brother 1 exhibited long-standing hypophosphatemia, ossification of the posterior longitudinal ligament, conductive hearing loss, congenital hip dysplasia, and aortic valve calcification. Brother 2 presented with progressive myelopathy and spinal stenosis, and underwent parathyroidectomy for presumed normocalcemic primary hyperparathyroidism. Postoperative hypoparathyroidism led to initiation of calcitriol and calcium supplementation, and subsequent nephrolithiasis. Both patients demonstrated FGF23-mediated renal phosphate wasting, low-normal 1,25-dihydroxyvitamin D, elevated parathyroid hormone and normocalcemia, favored to represent secondary rather than primary hyperparathyroidism, and significant abnormalities in cortical and trabecular bone parameters by HR-pQCT. These cases highlight diagnostic pitfalls in adult-onset ARHR2, including delayed recognition of FGF23-mediated phosphate wasting and misdiagnosis as primary hyperparathyroidism. Accurate genetic diagnosis is essential because ARHR2 clinically mimics X-linked hypophosphatemia, underscoring the need for early recognition to guide safe and effective treatment.

Ponticulus posticus (PP) is a bony bridge arising from the posterior arch of C1 toward the superior articular process or lateral mass; when complete, it forms an arcuate foramen over the C1 vertebral artery (VA) groove and may convert the VA path into an osseous canal. This anatomy can narrow the usual corridor for C1 lateral mass screw (LMS) insertion. We report a 68-year-old man who sustained an upper cervical cord injury (ASIA Impairment Scale grade [AIS] B) after a fall. Computed tomography (CT) revealed continuous ossification of the posterior longitudinal ligament and anterior longitudinal ligament from C2 to T1, and magnetic resonance imaging showed canal stenosis due to a retro-odontoid pseudotumor with intramedullary signal change. Dynamic flexion radiograph demonstrated an atlas-dens interval of 5.6 mm and a space available for the spinal cord of 15.5 mm, while three-dimensional computed tomographic angiography identified bilateral complete PP with an aberrant VA course and no symptoms of vertebrobasilar insufficiency. After C1 laminectomy, the arcuate bony bridge was microsurgically unroofed with a 3-mm high-speed burr, enabling direct visualization and protection of the VA with neurosurgical sheets and a Penfield dissector; unroofing was complete on the left and partial on the right based on the bony bridge morphology and the VA exit point. An intraoperative navigation system confirmed screw entry points and trajectories, allowing placement of C1 screws. Immediate postoperative CT confirmed appropriate screw positions. Postoperative vascular imaging was not performed. At three months, the patient's neurological status improved to AIS C, which indicates motor-incomplete spinal cord injury, with no implant-related complications. In bilateral complete PP, the risk of VA injury with C1 LMS has led to divergent recommendations ranging from avoidance to conditional use with protective techniques. Microsurgical unroofing placed the VA under direct visualization and protection, and navigation verified a controlled corridor, supporting intraoperative adjustments in complex C1-2 anatomy. In this setting, microsurgical unroofing with navigation permitted C1 LMS placement under direct VA visualization and protection and may be a reasonable option when a controlled corridor can be created in selected patients.

BACKGROUND AND OBJECTIVE: Anterior cervical spine surgery (ACSS) is commonly performed for degenerative, traumatic, infectious, and neoplastic conditions of the cervical spine and is generally associated with favorable outcomes and low complication rates. However, postoperative retropharyngeal hematoma is a rare but potentially catastrophic complication due to the risk of rapid airway compromise. This narrative review summarizes the anatomy, pathophysiology, incidence, risk factors, clinical presentation, management, and outcomes of retropharyngeal hematoma following ACSS. METHODS: A narrative review was performed using PubMed/MEDLINE, Google Scholar, and manual reference review. Search terms included "anterior cervical spine surgery", "anterior cervical discectomy and fusion", "retropharyngeal hematoma", "postoperative cervical hematoma", and "airway compromise". English-language human studies, including retrospective cohorts, case series, case reports, and relevant reviews, were included. Given the heterogeneity of available data, no formal quality scoring or meta-analysis was performed. KEY CONTENT AND FINDINGS: Retropharyngeal hematoma most commonly occurs within the first 24 hours after surgery, but delayed presentations after discharge have been reported. Presenting symptoms may include progressive dysphagia, hoarseness, neck swelling, stridor, dyspnea, and respiratory distress. Airway compromise primarily results from mechanical compression of the pharynx and larynx by an expanding hematoma, often with secondary soft tissue edema. Reported risk factors include multilevel surgery, coagulopathy or anticoagulation, poor perioperative blood pressure control, male sex, advanced age, medical comorbidity, ossification of the posterior longitudinal ligament (OPLL), and difficult airway morphology. Potential bleeding sources include vascular or soft-tissue oozing, as well as exposed cancellous bony endplates when open interbody cages are inadequately packed. Early recognition, airway control, emergent wound decompression when indicated, and surgical evacuation are central to management. CONCLUSIONS: Although uncommon, retropharyngeal hematoma following ACSS requires a high index of suspicion because deterioration can be rapid. Awareness of risk factors, meticulous hemostasis including bony endplate hemostasis, early postoperative monitoring, and prompt multidisciplinary airway management are essential. Prospective studies are needed to better define monitoring strategies and risk stratification models.

INTRODUCTION: Hypertrophy of the posterior longitudinal ligament (HPLL) is a rare cause of spinal cord compression, most commonly affecting the cervical spine. Thoracic and lumbar involvement are exceptional, and the natural history of HPLL, particularly its relationship to ossification of the PLL (OPLL), remains unclear. To our knowledge, this is the first reported case of diffuse thoracolumbar HPLL presenting with unusual features and showing no ossification at long-term follow-up. CASE PRESENTATION: We present a 50-year-old man with rapidly progressive paraparesis and gait disturbance. Imaging revealed a continuous, non-ossified, intraspinal, ventral lesion from T5 to L4, with severe cord compression at T10-L1, hypointense signaling on T1W and T2W images, and progression compared with the MRI performed 7 years earlier, suggestive of HPLL. The patient underwent anterior T10-L1 HPLL resection with fusion and posterior L1-L3 decompression, resulting in full neurological recovery. Histopathology demonstrated hyalinized collagenous tissue with chronic inflammatory infiltrates. After 13 years of follow-up, the patient remained ambulatory, with imaging showing persistent non-ossified HPLL in the thoracic and lumbar unresected regions, no recurrence at the resected region, and new thoracic anterior longitudinal ligament hypertrophy (HALL). DISCUSSION: This case illustrates a rare form of diffuse thoracolumbar HPLL with long-term stability and no transition to ossification, suggesting distinct biological pathways for HPLL and OPLL with the additional novel finding of HALL. The presence of chronic inflammation supports a potential role for inflammation-driven fibrosis in ligamentous hypertrophy. Tailored surgical strategies and vigilant long-term follow-ups are essential in managing HPLL.