Cervical spondylotic internal jugular venous compression syndrome

Abstract Aims This study aimed to identify the clinical profiles of cervical spondylosis‐related internal jugular vein stenosis (IJVS) comprehensively. Methods A total of 46 patients, who were diagnosed as IJVS induced by cervical spondylotic compression were recruited. The clinical manifestations and imaging features of IJVS were presented particularly in this study. Results Vascular stenosis was present in 69 out of the 92 internal jugular veins, in which, 50.7% (35/69) of the stenotic vessels were compressed by the transverse process of C1, and 44.9% (31/69) by the transverse process of C1 combined with the styloid process. The transverse process of C1 compression was more common in unilateral IJVS (69.6% vs 41.3%, P = 0.027) while the transverse process of C1 combined with the styloid process compression had a higher propensity to occur in bilateral IJVS (52.2% vs 30.4%, P = 0.087). A representative case underwent the resection of the elongated left lateral mass of C1 and styloid process. His symptoms were ameliorated obviously at 6‐month follow‐up. Conclusions This study proposes cervical spondylotic internal jugular venous compression syndrome as a brand‐new cervical spondylotic subtype. A better understanding of this disease entity can be of great relevance to clinicians in making a proper diagnosis.

the spinal cord, nerve roots, and vertebral arteries, whereas, in our clinical practice, we have noticed that a subset of patients with unexplained nonfocal neurological dysfunctions display cerebral venous outflow disturbance in relation to the atlas (C1) compression of the superior segment of the internal jugular vein (IJV). 1 Although current understanding of IJV stenosis (IJVS) is far from adequate, IJVS has been demonstrated to be associated with several central nervous system (CNS) disorders, including transient monocular blindness, Ménière disease, Alzheimer's disease (AD), idiopathic intracranial hypertension, and multiple sclerosis. [2][3][4][5][6][7][8] Accumulating evidence also reveals that extracranial venous outflow disturbance poses an undesirable effect on the cerebral arterial and venous circulation, thus resulting in varied neurological deficits. 9 Decreased cerebral perfusion, cerebral microvascular structures impairment, impaired cerebrospinal fluid (CSF) dynamics, and elevated intracranial pressure may be the underlining mechanisms of IJVS-induced brain structural and functional disorders. 10 Our study group discovered that some nonfocal neurological symptoms like headache, head noise, tinnitus, and visual impairment are tightly correlated to unilateral or bilateral IJVS, and balloon dilation with stenting in the stenotic segment may be a promising option to overcome nonimmunogenic and nonextrinsic compression IJVS-induced jugular venous outflow impairment. 11 Meanwhile, we also depicted the clinical characteristics and neuroimaging findings in IJVS in a previous publication. 12 Accordingly, symptomatic IJVS should be viewed as a pathological disorder, which deserves more attention from clinicians due to the limited realization and the disabling or long-lasting neurological symptoms that cannot be explained by other known diseases. 13 The IJV can be thought of as having three segments: the inferior (J1), mid (J2), and superior segments (J3). Given the anatomical fact that the J3 segment passes through the interval space between the C1 lateral tubercle and the styloid process, this part is more likely to be impinged by osseous structures from cervical spondylosis. 9,14,15 In this study, we aimed to identify the clinical profiles of cervical spondylosis-related IJVS in attempt to gain a deeper understanding of the negative impact of cervical spondylotic IJV compression syndrome on CNS. University, were enrolled in this study. The diagnosis of cervical spondylotic IJVS was confirmed by magnetic resonance venography (MRV) and/or computed tomographic venography (CTV). Other imaging modalities, including catheter venography (CV), magnetic resonance imaging (MRI), cervical duplex ultrasound, and single-photon emission computed tomography (SPECT), were conducted in a portion of the patients as well. All the imaging tests were performed in the supine position.

| ME THODS
Patients with cervical spondylotic IJVS should comply with each item as follows: (a) the stenotic segment narrowing of ≥50% in respect to the proximal adjacent jugular vein segment, as shown in MRV, CTV, or CV; (b) at least one abnormal collateral vessel ≥50% of the maximal diameter of the adjacent IJV or at least two abnormal collateral vessels <50% of the maximal diameter of the adjacent IJV, as depicted by MRV, CTV, or CV; (c) IJVS secondary to the compression from the cervical lateral mass with or without the styloid process, as depicted by CTV; (d) with unexplained nonfocal neurological deficits or other symptoms. 10,16,17 All patients received standard medical therapy, including antiplatelets/anticoagulation, dehydration, and other symptomatic treatment to prevent against venous thrombosis, decrease intracranial hypertension, and relieve afflicted symptoms. 10,12 As there is no consensus over the surgical intervention for such osseous impingement, only patients who strongly requested surgery were performed with cervical lateral mass resection and subsequent stenting/balloon dilatation. SPSS 19.0 was used in this study for data analysis. Continuous variables following Gaussian distribution were expressed as mean ± standard deviation (SD) and analyzed by t test or one-way analysis of variance (ANOVA); otherwise, they were presented as median (interquartile range, IQR) and analyzed by Mann-Whitney U test. Categorical variables were depicted as number (percentage) and analyzed by chi-square test. A P-value < 0.05 was considered as statistical significance.  Table 1.  Representative IJVS imaging characteristics are presented in Table 2.

| Clinical features between uni-and bilateral IJVS
As shown in Table 3, the percentage of patients with unilateral cervical spondylotic compression-induced IJVS was nearly equivalent to that of bilateral compression-induced IJVS. It was found that the C1 transverse process compression was more common in unilateral than that in bilateral IJVS (69.6% vs 41.3%, P = 0.027). In contrast, dual compression from the lateral mass of C1 combined with the styloid process was more prone to occur in bilateral IJVS compared with that in unilateral IJVS (52.2% vs 30.4%, P = 0.087). The clinical manifestations aforementioned in unilateral IJVS were well matched with that in bilateral IJVS subgroup. In addition, the average age of symptom onset and the average duration between symptom onset and admission to our clinical center were similar between two IJVS subgroups.  To our knowledge, extracranial venous drainage impairment is associated with a number of brain disorders. 10  Importantly, stenosis and abnormal collateral veins shown by MRV or CTV are essential for the diagnosis of symptomatic IJVS. 17 At this time, an inadequate understanding of symptoms and signs of cervical spondylotic IJVS may underestimate its clinical significance. All patients in this study had been misdiagnosed before they were admitted into our institution (the longest duration of misdiagnosis is 8 years). Therefore, in addition to reporting a special cervical spondylosis subtype-cervical spondylotic IJVS, this study also provides a valuable reference for clinicians who are unfamiliar with this novel concept, whereby decreasing the rate of misdiagnosis and treatment delay.
The main reason for the focal stenosis at the IJV-J3 segment was due to the transverse process with or without styloid process compression in this cohort of patients. Two patients with styloid process compression alone were ruled out from the analysis, as this issue does not belong to cervical spondylosis. Moreover, it has been reported that patients with styloidogenic IJVS might benefit from decompressive styloidectomy. 14,15 Other extrinsic or nonextrinsic stenoses were excluded from this study as well. Risk factors for nonextrinsic stenoses have not been determined currently, whereas, our clinical practice implies that certain systemic disorders, such as autoimmunity diseases, hypertension and diabetes may be associated with venous wall anomalies of the IJV. 10  Note: Of the 69 stenotic vessels, 68 were secondary to extrinsic osseous compression (five stenotic vessels were also compressed by the nearby carotid arteries) and the remaining one stenotic vessel was not associated with external compression. extrinsic impingement of the IJV, stenting alone was deemed ineffective and might even exacerbate the outflow disturbance. 14 In this condition, decompressive bone resection may serve as a potential therapeutic strategy, which not only relieves IJVS-associated symptoms but also lowers the complications of stenting. 14 In this study, only one case underwent bone resection and unilateral balloon dilation. Despite the lack of long-term follow-up data, the functional outcome of this patient has been satisfactory so far.
Accordingly, larger prospective trials exploring the efficacy and safety of surgical intervention in patients with cervical spondylotic IJVS are warranted.
There are several limitations in the study. First of all, the small sample size may bias the epidemiological results in this study.
Second, the severity of some symptoms was not quantified. Given that, the exact difference between unilateral IJVS and bilateral IJVS could not be assessed accurately. Finally, only one case underwent surgical intervention without complete follow-up data. Therefore, the efficacy and safety of bone resection could not be concluded in this study.

| CON CLUS ION
This study proposes cervical spondylotic IJV compression syndrome as a new cervical spondylosis subtype. A better understanding of the clinical presentations and imaging features of this type of cervical spondylosis can be of great relevance to clinicians in making a proper diagnosis.
Compression from the transverse process of C1 alone was more common in unilateral IJVS, while dual compression from the transverse process combined with the styloid process was more likely in bilateral IJVS Moreover, the lateral tubercle and styloid process resection may be a promising option to address cervical spondylotic IJVS-associated symptoms. Given the limitations mentioned above, well-designed clinical trials with large sample size are required to further investigate this disorder.