Niemann-Pick disease is a group of rare conditions passed down in families. The conditions affect the body’s ability to break down and use fats, such as cholesterol and lipids, inside cells. Because of the buildup of fats, these cells don’t work as they should and, over time, the cells die. Niemann-Pick disease can affect the brain, nerves, liver, spleen and …

Peripheral neuropathy is an umbrella term for nerve diseases that affect a specific subdivision of your nervous system. Many different conditions can cause peripheral neuropathy, which means a wide range of symptoms is also possible. Peripheral neuropathy can also affect different body parts, depending on how and why it happens. What this name means The term “peripheral” is from the …

A neurofibroma is a benign tumor that develops along your nerve cells. This tumor is a symptom of a group of rare, inherited conditions called neurofibromatosis. People born with neurofibromatosis may have tumors on their skin, under their skin or deeper in their bodies. Most neurofibromas don’t cause medical problems. Some larger neurofibromas can affect many nerves and cause serious medical issues. …

Neuroendocrine tumors (NETs) are a group of uncommon tumors that start in your neuroendocrine cells. These cells combine the traits of nerve cells and hormone-producing endocrine cells. Most neuroendocrine tumors are malignant (cancerous). There are several types of neuroendocrine tumors with symptoms that are easy to mistake for other less serious conditions. The characteristics of NETs — including how aggressive (fast-growing) they are, the symptoms they cause and …

Schwannomatosis is a broad name for several genetic conditions that cause tumors to form on nerves in your body. These tumors are known as schwannomas. They develop from insulating nerve cells called Schwann cells in your peripheral nervous system (nerve roots, nerves and nerve-muscle junctions). Schwannomatosis usually leads to chronic pain that typically starts in early adulthood. Schwannomatosis is a type of neurofibromatosis. This is a group of …

A schwannoma is a tumor that develops from the Schwann cells in your peripheral nervous system or nerve roots. Schwannomas are almost always benign (noncancerous) but can sometimes be malignant (cancerous). They’re usually slow-growing. Schwann cells assist the conduction of nerve impulses. They wrap around peripheral nerves and provide protection and support. Your peripheral nervous system includes nerves that travel from your spinal cord and brain to carry …

Postherpetic neuralgia (PHN) is a complication of shingles infection (also called herpes zoster). Shingles is caused by the reactivation of the varicella-zoster virus, which is the same virus that causes chickenpox. Shingles causes a painful, blistering rash and other symptoms. The rash most commonly occurs in a band pattern on one side of your body, usually on your trunk (central core of …

Nephrotic (neff-rot-ick) syndrome is a condition in which your kidneys release an excessive amount of protein (proteinuria) in your urine (pee). Nephrotic syndrome usually results from a problem with your kidneys’ filters (glomeruli). Glomeruli (glo-mare-yoo-lye) are tiny blood vessels in your kidneys. They remove wastes and excess fluids from your blood and send them to your bladder as urine. Common …

Nephrogenic systemic fibrosis (NSF) is a rare disease that occurs mostly in people with kidney disease after exposure to gadolinium-based contrast agents (GBCAs). Gadolinium is a substance found in contrast dye. Healthcare providers use contrast dye during imaging tests like magnetic resonance imaging (MRI). Having kidney damage puts you at risk for NSF because your kidneys have trouble filtering GBCAs from your bloodstream. NSF causes …

Nasal polyps are painless and benign (noncancerous) growths. They form in the mucosa (thin, soft tissue) that lines your nasal and sinus passages. They usually appear on both sides of your nose. Nasal polyps can get irritated and swollen, making it hard for you to breathe through your nose. Small polyps are teardrop-shaped. But as they grow larger, they often resemble peeled grapes …