5 Rare Neurological Conditions

Uncontrollable high blood pressure is the hallmark of pheochromocytoma, an endocrine tumor that grows in your adrenal glands, two small hormone-producing glands that sit atop your kidneys.

Pheochromocytoma stimulates the release of excess catecholamines -- hormones including dopamine, adrenaline, metanephrine and noradrenaline the body uses to manage your heart rate, blood pressure, blood sugar and its response to stress. When your body feels stressed, it floods your bloodstream with catecholamines (fight or flight, remember?). When it's a tumor triggering the release of those hormones rather than your body's natural stress response, it can cause chronic, uncontrollable hypertension, headaches, heart palpitations and excessive sweating. It can also cause anxiety, nervousness, paleness, nausea, weight loss, chest or abdominal pain, fatigue and weakness [source: Cleveland Clinic].

Most pheochromocytomas are in the adrenal glands -- more than 90 percent -- and as many as 98 percent are within the abdomen [source: Blake]. When a pheochromocytoma grows outside the adrenal glands it's called a paraganglioma. Paragangliomas often grow in the head and neck, chest, abdomen, or pelvis [source: Pheo-Para Alliance].

Agnosia is a condition where you are unable to properly perceive objects.

It's the result of damage to the brain, usually in the occipital lobe (which is where the brain handles visual processing) or parietal lobes (where the brain processes peripheral sensory information). It affects how your brain is able to identify and perceive objects around you.

Agnosia may impact any of the senses, although it usually only affects a single sense. For example, a person suffering from auditory agnosia may not be able to identify a sneeze based on its sound, but would have no trouble visually identifying a person who is sneezing. A person suffering from visual agnosia may not be able to distinguish the spoon in a set of flatware but has no problem with sense of taste. If you suffer from gustatory agnosia, you may not be able to identify your favorite culinary dish. And so on. This type of damage may result from a tumor, injury or degeneration, and may be caused by stroke, dementia, brain lesions, and other neurological problems and developmental conditions.

While most people will recover from agnosia within three months, it may take as much as a full year for the condition to resolve.

Paraneoplastic neurologic syndromes (PNS), also called paraneoplastic neurologic disorders, happen when the body's immune system has an abnormal response to a neoplasm, a cancerous tumor. The body's white blood cells -- antibodies the body uses to attack those cancer cells -- begin to attack normal, healthy cells in the nervous system while fighting the tumor. This accidental attack on healthy nerve cells can sometimes trigger a paraneoplastic neurologic disorder -- it's estimated that fewer than 1 percent of cancer patients are diagnosed with PNS [source: Santacroce].

Symptoms of paraneoplastic neurologic disorders vary and, to simplify things, are divided into eight categories, including: cutaneous, endocrine, gastrointestinal, hematoligic, miscellaneous (nonspecific), neuromuscular, renal and rheumatologic [source: Santacroce]. Some of the more common symptoms include difficulty walking and maintaining balance, loss of muscle coordination, muscle weakness, loss of fine motor skills, vertigo or dizziness, vision problems, memory loss, dementia, numbness or tingling in the extremities, difficulty swallowing, slurred speech and seizures [source: Mayo Clinic].

Batten disease is a rare genetic condition that's part of a group of progressive degenerative neurometabolic disorders known as neuronal ceroid lipofuscinoses (NCLS). Currently, it can't be prevented and it is fatal.

The disease causes lipopigments, which are fats and proteins, to abnormally build up in the body's tissues. The disease often begins with vision problems or seizures, followed by significant degeneration of motor coordination and changes in behavior and personality. Seizures and visual impairment worsen as the disease progresses, and sufferers are often blind as well as mentally and physically impaired by the time they lose their battle with the disease.

There are a few types of NCLS disorders -- each type is based on the age symptoms appear rather than the symptoms themselves, which are similar across age groups. Batten disease usually is reserved to describe the condition when it occurs in kids, making itself known by the time the child is between 5 and 10 years old. There is also a form that affects newborns, who die shortly after birth. Other forms may develop during infancy and the toddler years, emerging at about 6 months to 2 years, as well as in early childhood, with symptoms occurring between ages 2 to 4. Adult NCLS appears before age 40, and symptoms are usually less severe than when it develops in children.

Ataxia is caused by disease or injury that damages your spinal cord or nerve cells in your cerebellum, the part of the brain that handles muscle coordination.

People with the condition lose muscle coordination during voluntary movements. Walking, for example, is a voluntary movement as is speaking, both of which can be impacted by ataxia. Blinking your eyes, on the other hand, is an involuntary movement and controlled by a different part of the body.

Head injuries, such as from a car accident, stroke, transient ischemic attack, multiple sclerosis, cerebal palsy, some cancers, tumors and sometimes viruses such as varicella zoster virus (that's the virus that causes chickenpox) may cause ataxia. Sometimes toxic levels of alcohol, drugs and certain medications, as well as lead or mercury poisoning, may be to blame. Ataxia may also run in some families, a genetic condition where the body produces abnormal proteins that eventually cause nerve cells to degenerate. Sometimes, though, ataxia doesn't seem to have a cause, known as sporadic degenerative ataxia -- it's estimated that about 150,000 Americans live with heredity or sporadic types of ataxia [source: National Ataxia Foundation].