Causes of Secondary IH
Intracranial hypertension was first documented in the sixteenth century by a Dutch explorer, Gerrit de Veer, who identified the toxic effects of polar bear liver on early Artic explorers. Several men in his expedition developed secondary intracranial hypertension (SIH) and nearly died after consuming polar bear liver, which contains lethal levels of Vitamin A. Excessive ingestion of vitamin A is now a recognized SIH cause.
Other examples of SIH causes include:
- Head trauma (including post-traumatic brain injury (TBI)
- Stroke (subarachnoid hemorrhage)
- Cerebral blood clots (dural venous thrombosis)
- Kidney failure
- Liver failure
- Sleep apnea
Drugs associated with IH:
- Tetracycline
- Minocycline
- Isotretinoin (Accutane)
- All-trans retinoic acid (used in the treatment of promyelocytic leukemia)
- Excessive ingestion of Vitamin A (hypervitaminosis A)
- Amiodarone
- Nitofurantoin
- Lithium
- Levonorgestral (Norplant)
- Growth hormone treatments
- Steroid withdrawal
Underlying infectious diseases:
- Meningitis (bacterial or viral)
- Lyme disease
- Human immunodeficiency virus (HIV)
- Poliomyelitis
- Coxsackie B viral encephalitis
- Guillain-Barre syndrome
- Infectious mononucleosis
- Syphilis
- Malaria
Other underlying diseases:
- Lupus
- Sarcoidosis
- Hypoparathyroidism
- Addison’s disease
- Behcet disease
More SIH causes are thought to exist, but research is needed to confirm whether there are true relationships. Both idiopathic and secondary intracranial hypertension can cause the same physical symptoms of raised intracranial pressure and can become chronic; the main difference between the two forms is the presence of a cause.