Women with Idiopathic Intracranial Hypertension (IIH) may suffer from increased pressure inside the skull due to excess cerebrospinal fluid, which can cause migraine headaches and blindness.
What is Nexplanon?
Nexplanon is a subcutaneous birth control implant that prevents pregnancy by slowly releasing the hormone etonogestrel for three years. It is manufactured by Merck & Co. and was developed as a newer version of Implanon. Both implants are matchstick-sized plastic rods that are implanted under the skin on a woman’s upper arm.
Does Nexplanon Cause Idiopathic Intracranial Hypertension?
No one knows if Nexplanon causes Idiopathic Intracranial Hypertension (IIH). It is a disease of unknown origin (“idiopathic”). Although IIH primarily affects obese women of childbearing age, it is also associated with birth control. One study published in 1995 by the New England Journal of Medicine documented 56 cases of IIH in women who used a subcutaneous birth control implant containing levonorgestrel. Exogenous estrogen and progestin-only birth control injections have also been associated with case reports of IIH.
Secondary intracranial hypertension is a disease that occurs when a blood clot physically obstructs the flow of cerebrospinal fluid, which elevates pressure inside the skull. In 2012, the British Medical Journal published a study linking the use of birth control implants with a 40% increased risk of blood clots. If these blood clots grow in arteries, they can potentially travel to the brain and cause a stroke. Click here to read more.
Headaches are one of the most common side effects of Nexplanon, estimated to affect 25% of women. Headaches are also a symptom of IIH that occur in over 90% of people with the disease. These headaches are often dull, located at the back of the head, and worst in the morning. Without treatment, headaches associated with IIH can become constant and very painful. In some cases, headaches can be relieved by removing cerebrospinal fluid through a lumbar puncture (spinal tap).
IIH puts pressure on the optic nerve. This can produce symptoms like double-vision, blurry vision, temporary blindness, and light-sensitivity. It can also cause a complication known as papilledema, in which pressure on the optic disc (“blind spot”) causes swelling. When IIH is damaging vision, doctors may recommend surgery to drain fluid from the skull. Without treatment, IIH can cause permanent blindness. About 5% of people who are diagnosed with IIH develop blindness.