Idiopathic Intracranial Hypertension (IIH) is a neurological disorder characterized by elevated pressure within the skull. This increased pressure is caused by an excessive buildup of cerebrospinal fluid (CSF) surrounding the brain and spinal cord. The Mirena device is a long-acting, reversible contraceptive, a levonorgestrel-releasing intrauterine system (IUS). Levonorgestrel is a synthetic progestin hormone slowly released into the uterus. The question of whether IIH resolves after Mirena removal stems from the suspected relationship between the hormonal IUS and the development of this pressure disorder.
Understanding Idiopathic Intracranial Hypertension
Idiopathic Intracranial Hypertension is defined by high pressure within the cranium when no other cause, such as a tumor or blood clot, can be identified. IIH results when cerebrospinal fluid (CSF) is not adequately drained or is produced in excess. This imbalance causes the pressure to rise, pushing on the brain tissue and the optic nerves.
The primary symptoms involve severe, often debilitating headaches that may be worse in the morning or with positional changes. A characteristic symptom is pulsatile tinnitus, a rhythmic whooshing or ringing sound in the ears that pulses with the heartbeat.
The most serious concern is the effect on vision. Increased pressure on the optic nerve causes it to swell, a condition known as papilledema, which is detected during an eye examination. If this swelling continues, it can lead to progressive visual field loss and potentially permanent blindness. Diagnosis is confirmed by a lumbar puncture, which measures the opening pressure of the CSF.
Examining the Potential Connection Between Mirena and IIH
The suspicion that the Mirena IUS contributes to IIH is rooted in its active component, levonorgestrel, a synthetic progestin. Other hormonal medications, including certain oral contraceptives, steroids, and high-dose progestins, have a documented association with elevated intracranial pressure. Scientists theorize that the hormone may interfere with the production or absorption of CSF, leading to pressure buildup.
Mirena delivers a localized, low dose of levonorgestrel primarily to the uterus, but a small amount of the hormone still enters the systemic circulation. Case reports detailing IIH symptoms following insertion have been published, suggesting a causal link. However, large-scale epidemiological studies have not consistently established Mirena as a direct, independent cause of IIH.
IIH is most common in overweight women of childbearing age, and obesity is the most significant and well-established risk factor. Distinguishing whether the IIH is a spontaneous occurrence, an effect of the hormonal device, or related to underlying risk factors remains a challenge in individual cases.
Outcomes Following Mirena Removal
Resolution of IIH after Mirena removal is reported in some patients, though it is not guaranteed. If the device was a contributing factor, removal eliminates the suspected hormonal trigger, which can lead to a reduction in intracranial pressure. Symptom resolution timing varies, with some patients noting improvement in headaches and visual symptoms within weeks to months.
However, IIH is known to have a natural history that includes spontaneous remission, meaning symptoms can resolve without intervention. Furthermore, the underlying primary risk factor, such as obesity, often remains after removal, and the IIH persists regardless of the device’s absence.
Removal of the Mirena IUS is a reasonable step for concerned patients but is not guaranteed to resolve the condition. Ophthalmological and neurological follow-up are necessary after removal to monitor intracranial pressure and vision status. Monitoring ensures that persistent or recurring IIH is addressed promptly to prevent permanent vision loss.
Standard Medical Management for Persistent IIH
If IIH symptoms continue after Mirena removal, or if the device is deemed unrelated, standard medical management is initiated. The most effective non-pharmacological intervention, particularly for overweight patients, is weight loss. Achieving a modest reduction, often 5% to 10% of total body weight, significantly reduces intracranial pressure and resolves papilledema.
The first-line pharmacological treatment is acetazolamide, a medication that decreases the rate of cerebrospinal fluid production. This drug is gradually increased until the intracranial pressure is controlled. Another drug sometimes used is topiramate, which manages headaches and promotes weight loss.
For severe cases where vision is rapidly deteriorating and medical therapy has failed, surgical intervention may be necessary. Procedures include placing a shunt (e.g., a lumboperitoneal shunt) to drain excess CSF, or performing an optic nerve sheath fenestration, which involves making small incisions to relieve pressure.