Women of childbearing age who are already at risk for pseudotumor cerebri may inadvertently aggravate that risk by taking hormonal birth control.

Pseudotumor cerebri, also often referred to as intracranial hypertension, is the appearance of symptoms resembling those of a brain tumor when no actual tumor is present. It results from an increase in pressure that is presumably related to an increase in cerebrospinal fluid inside the skull.

The most common pseudotumor cerebri symptoms include a headache, often accompanied by nausea, vomiting or dizziness. Patients may also experience tinnitus (ringing in the ears) or stiffness and pain in the neck and shoulders. There may also be visual symptoms such as blurriness, dimness, double vision, seeing flashing lights, trouble with peripheral vision, and passing moments of blindness known as visual obscurations. And even after symptoms resolve, they sometimes recur months or years later.

Diagnosis of pseudotumor cerebri is done by clinical exam, sometimes with brain imaging studies to rule out other causes like tumors or blood clots. It may be necessary to undergo a spinal tap, or lumbar puncture. Treatment may require medications usually used for migraines or glaucoma, and surgery may be necessary to release cerebrospinal fluid from the interior of the skull.

Sometimes the increase in pressure on the optic nerve can cause a swelling of the optic nerve called papilledema, which itself causes loss of vision that may be permanent. Vision problems may require surgical correction.

Obesity is the most prevalent risk factor for pseudotumor cerebri. In women of childbearing age, the condition may develop with even a moderate gain of weight.

Causes of Pseudotumor Cerebri

While the root cause of pseudotumor cerebri is unknown, it may be associated with certain types of hormonal birth control.

A study published in the New England Journal of Medicine in 1995 found a possible link between intracranial hypertension and certain levonorgestrel-based birth controls. Levonorgestrel is the active ingredient in some emergency oral contraceptives, including the brand names My Way and Plan B One Step. Levonorgestrel is also administered as regular birth control via intrauterine implants such as Liletta, Mirena and Skyla.

Another study published in the journal Eye in 2006 examined the case of a 23-year-old woman who developed intracranial hypertension after using medroxyprogesterone acetate, marketed as Depo-Provera. Her symptoms began with three weeks of headaches pain behind the eyes, double vision, diplopia, and nausea. Her only medication had been a dose of medroxyprogesterone acetate taken two months previously. Her clinical exam revealed papilledema and nerve fiber hemorrhages in both eyes. She chose to discontinue her birth control, and four months later her symptoms had resolved. The researchers commented that the close temporal relationship between her use of medroxyprogesterone acetatand her pseudotumor cerebri symptoms suggested a causal relationship between the two.

Depo-Provera is a birth control that prevents ovulation and changes the cervical mucus and uterine lining in such a way that reduces the possibility of pregnancy. It’s administered via injections given once a week to once every three months.

In addition to being used in birth control, medroxyprogesterone is also used to regulate ovulation and to treat irregular, excessive, or absent menstruation. It’s also used to reduce the risk of endometrial hyperplasia in patients undergoing estrogen therapy.