Idiopathic intracranial hypertension (IIH) is a rare condition that causes elevated intracranial pressures of unknown etiology [6].The incidence of IIH ranges from 1 to 3 patients per 100,000 people per year [1],and primarily affects obese women as approximately 90% of those diagnosed with IIH are obese female [6].It is unclear exactly why obesity is so closely related to the development of IIH, however, it is thought that the increased intra-abdominal pressure could lead to an increase in the filling pressure of the right heart, resulting in increased venous pressure [7].
Typically, the three symptoms representative of IIH include daily severe headache, papilledema, and vision loss [8].Papilledema is generally considered to be the primary symptom of IIH and can lead to severe morbidity if left untreated [9],and advanced cases occur in 10% to 20% of patients with IIH and may progress to permanent blindness through optic nerve atrophy at highly variable rates (weeks to years)[8].Although headaches are the most reported symptom, visual loss remains the most feared complication [10].
The exact cause of IIH is unknown, but there have been several proposed mechanisms attempting to explain its occurrence, such as CSF hypersecretion, normal CSF access blocked, CSF absorption disorder, venous sinus thrombosis and some unknown reasons. IIH is predominately a diagnosis of exclusion [11] (see Table 1 for the modified Dandy diagnostic criteria).
For patients with simple vision loss, medication may be effective for a short period of time, but long-term use may lead to gradual vision loss and even the risk of blindness. Therefore, surgical treatment should be performed for patients who fail to respond to conservative treatment. Dandy [12] believes that increased cerebral blood flow or cerebrospinal fluid volume leads to increased intracranial pressure, which leads to symptoms related to intracranial hypertension and optic papillomedema, leading to progressive vision loss and blindness. Therefore, IIH is typically treated with shunts, and both LPS and VPS can reduce intracranial pressure and have a certain effect on visual impairment by shunting CSF to reduce compression of the arteries and veins around the optic nerve. They are safe, effective and has a good short -term effect for LP and VP shunts in the treatment of IIH-induced headache and papilledema, as well as the improvement of visual acuity loss and/or visual field defects.
Complications of LPS surgery mainly include decreased intracranial pressure caused by excessive shunt, blockage of shunt tube, infection, and cerebrospinal fluid leakage [13]. In addition, due to excessive shunt of LPS, it is easy to be complicated with iatrogenic Chiari malformation and slit ventricle syndrome. Moreover, several reports show that the LPS technique is associated with a 60% rate of revision [14,15], a 4% rate of iatrogenic Chiari malformation [16], and an 18.5% rate of iatrogenic radicular pain [15].Therefore, in order to avoid the formation of iatrogenic Chiari malformation and slit ventricle syndrome, the postoperative CSF pressure of LPS was higher than VPS, so VPS has better effect on headache and vision recovery in patients with idiopathic intracranial hypertension than LPS. Moreover, complications following LPS have been reported [17] in 18% to 85% of cases, and the need for multiple revision surgeries and frequent wound complications have prompted many to abandon this procedure for the treatment of idiopathic intracranial hypertension, in favor of VPS. However, shunt tube blockage is a common complication of VPS. Ventricular end obstruction is mainly caused by excessive cerebrospinal fluid shunt, smaller ventricle, and the ventricle end of the shunt tube is buried in the brain tissue. It is possible that shunt failure rates may be similar between LP and VP shunts, but reasons for revision, removal, or replacement may differ. Therefore, It is necessary to find a solution to the blockage of the shunt tube—the SVPS technology.
Nowadays, as rates of obesity rise globally, IIH is expected to become increasingly common [18]. CSF shunting currently remains the primary treatment for acute reduction of symptom severity. The effectiveness and safety of VPS in the presence of IIH has been greatly increased with the advent of image guidance. Image guidance allows the procedure to be performed safely and accurately, and some series use image guidance to achieve 100% placement of a VPS with only one pass of the catheter needed on each patient [19].And the SVPS is noted to have a higher medium-term patency rate than LPS [5].Consequently, it might reduce the rate of shunt revision, particularly those due to proximal obstructions [20].More surprisingly, the associated concomitant symptoms/triggers of IIH are addressed, such as hypertension. So, we need to further investigate the relationship between hypertension and IIH in hypertensive IIH patients.