Some of the most popular types of birth control contain hormones that have been associated with cases of Idiopathic Intracranial Hypertension (IIH). This serious neurological condition can potentially lead to chronic headaches and loss of vision. In some cases, patients need surgery to prevent permanent blindness.
What is Implanon?
Implanon is a matchstick-sized contraceptive that is implanted under the skin on the upper arm. It slowly releases the hormone etonogestrel, which prevents pregnancy for up to three years. Implanon was approved by the FDA in 2006 and it is manufactured by Merck & Co.
What is the problem?
Headaches were reported in 25% of women on Implanon during clinical trials and they are a common side effect of many hormonal contraceptives. Headaches are also a symptom of idiopathic intracranial hypertension (IIH), a serious medical condition that occurs when pressure in the skull increases due to excess cerebrospinal fluid.
Implanon and IIH
No studies have shown that Implanon causes IIH. The term “idiopathic” means “of unknown cause.” However, birth control is a possible risk-factor. Evidence linking contraceptives and IIH has been growing for decades.
In 1995, the New England Journal of Medicine published a study linking 56 cases of IIH to a contraceptive implant containing the hormone levonorgestrel. Since then, other studies have linked cases of IIH with exogenous estrogen and progestin-only injection birth control.
Complications of IIH
Normally, cerebrospinal fluid surrounds the brain and spinal cord. It is supposed to act like a shock-absorber to cushion the brain from impacts. When there is too much fluid, it puts pressure on the brain — similar to the effects of a growing brain tumor. In the past, IIH was known as pseudotumor cerebri (PTC).
Complications from IIH may include:
- Headaches: Often cause dull pain that is throbbing or pulsating, located in one part of the head, worst first thing in the morning, or increasingly frequent until they are constant.
- Vision problems: IIH can put pressure on the optic nerve, which transmits information between the brain and eyes. If the nerve is damaged, permanent vision problems may occur. They include double-vision, blurry vision, temporary blindness, enlarged blind spot, or permanent blindness.
- Papilledema: Occurs when pressure on the optic disc (blind spot) causes swelling. May be diagnosed with an eye exam.
- Tinnitus: Hearing problems may include ringing or “whooshing” sound in the ear due to pressure on internal structures of the ear.