Idiopathic intracranial hypertension pathogenesis: The jugular hypothesis.

In spite of expanding research, idiopathic intracranial hypertension (IIH) and its spectrum conditions remain challenging to treat. The failure to develop effective treatment strategies is largely due to poor agreement on a coherent disease pathogenesis model. Herein we provide a hypothesis of a unifying model centered around the internal jugular veins (IJV) to explain the development of IIH, which contends the following: (1) the IJV are prone to both physiological and pathological compression throughout their course, including compression near C1 and the styloid process, dynamic muscular/carotid compression from C3 to C6, and lymphatic compression; (2) severe dynamic IJV stenosis with developments of large cervical gradients is common in IIH-spectrum patients and significantly impacts intracranial venous and cerebrospinal fluid (CSF) pressures; (3) pre-existing IJV stenosis may be exacerbated by infectious/inflammatory etiologies that induce retromandibular cervical lymphatic hypertrophy; (4) extra-jugular venous collaterals dilate with chronic use but are insufficient resulting in impaired aggregate cerebral venous outflow; (5) poor IJV outflow initiates, or in conjunction with other factors, contributes to intracranial venous hypertension and congestion leading to higher CSF pressures and intracranial pressure (ICP); (6) glymphatic congestion occurs but is insufficient to compensate and this pathway becomes overwhelmed; and (7) elevated intracranial CSF pressures triggers extramural venous sinus stenosis in susceptible individuals that amplifies ICP elevation producing severe clinical manifestations. Future studies must focus on establishing norms for dynamic cerebral venous outflow and IJV physiology in the absence of disease so that we may better understand and define the diseased state.

Dynamic internal jugular vein venography: a descriptive study in 89 patients with suspected cerebral venous outflow disorders.

BACKGROUND: Internal jugular vein (IJV) stenosis has recently been recognized as a plausible source of symptom etiology in patients with cerebral venous outflow disorders (CVD). Diagnosis and determining surgical candidacy remains difficult due to a poor understanding of IJV physiology and positional symptom exacerbation often reported by these patients. METHODS: A retrospective single-center chart review was conducted on adult patients who underwent diagnostic cerebral venography with rotational IJ venography from 2022 to 2024. Patients were divided into three groups for further analysis based on symptoms and diagnostic criteria: presumed jugular stenosis, near-healthy venous outflow, and idiopathic intracranial hypertension. RESULTS: Eighty-nine patients were included in the study. Most commonly, ipsilateral rotation resulted in ipsilateral IJV stenosis and gradient development at C4-6 and contralateral stenosis and gradient appearance in the contralateral IJV at C1, with stenosis and gradient development in bilateral IJVs at C1-3 bilaterally during chin flexion. In all patients, 93.3% developed at least moderate dynamic stenosis of at least one IJV, more than two-thirds (69.7%) developed either severe or occlusive stenosis during rightward and leftward rotation, and 81.8% developed severe or occlusive stenosis with head flexion. Dynamic gradients of at least 4 mmHg were seen in 68.5% of patients, with gradients of at least 8 mmHg in 31.5% and at least 10 mmHg in 12.4%. CONCLUSION: This study is the first to document dynamic changes in IJV caliber and gradients in different head positions, offering insights into the complex nature of venous outflow and its impact on CVD.

Cerebral venous pressures, sinus trans-stenosis gradients, and intracranial pressures are dramatically augmented by head position.

BACKGROUND: Cerebral venous pressures, sinus trans-stenosis gradients, and intracranial pressures are thought to be influenced by head position. OBJECTIVE: To investigate the intracranial manifestations of these changes in patients with cerebral venous outflow disorders (CVD). METHODS: A retrospective chart review was conducted on 22 consecutive adult patients who underwent diagnostic cerebral venography with rotational internal jugular vein (IJV) venography and superior sagittal sinus (SSS) pressure measurements in multiple head positions. Data on venous sinus pressures, IJV pressures, and lumbar puncture (LP) opening pressures (OP) were collected and analyzed. RESULTS: The study found that 21 (96%) patients experienced increases in SSS pressures with head rotation, with a mean increase of 25.4%. Intracranial trans-stenosis gradients showed significant variability with head position. Additionally, LP OP measurements increased by an average of 44.3% with head rotation. Dynamic IJV stenosis was observed in all patients during rotational testing. CONCLUSION: Head position significantly affects cerebral venous pressures, trans-stenosis gradients, and intracranial pressures in patients with CVD or intracranial hypertension. These findings highlight the need for dynamic venography in the diagnostic evaluation of these conditions to better understand their pathophysiology and improve treatment strategies.

The correlation between intracranial pressure and venous sinus pressures changes after venous sinus stenting.

BACKGROUND: The pathophysiology of idiopathic intracranial hypertension (IIH) and other cerebral venous outflow disorders (CVD) has largely been unexplored. While a correlation between venous sinus pressure and opening pressure (OP) has been previously noted, there are limited data on this relationship in patients with prior venous sinus stenting (VSS). METHODS: A single center retrospective chart review was conducted on CVD patients who underwent diagnostic cerebral venography with manometry followed immediately by lateral decubitus lumbar puncture, from 2016 to 2024. RESULTS: 206 patients underwent 216 total procedures and were included. Among all patients, there was a moderate nearly one-to-one correlation between OP and torcular or superior sagittal sinus (SSS) pressures. Thirty-two patients underwent testing after having undergone VSS. Patients with previous VSS showed a significantly altered relationship between venous pressures and OP, whereby as venous sinus pressures increased, OP increased more gradually in previously stented patients compared with non-stented patients. For example, when OP was fixed at 21 mm Hg and body mass index at 30 kg/m2, predicted mean SSS pressure was 19.47 mm Hg in non-stented patients versus 16.91 mm Hg in stented patients. CONCLUSION: This study confirmed a strong relationship between OP and venous sinus pressure in CVD patients. However, patients with previous VSS demonstrated an altered relationship with higher CSF pressures relative to venous pressures compared with naïve patients. This finding may have important clinical implications in the management of IIH patients.