Definition

• Nerve cells in the brain use a chemical called dopamine to control muscle movement. Parkinson's Disease afflicts people when those nerve cells are destroyed. "Without dopamine, the nerve cells in that part of the brain cannot properly send messages. This leads to loss of muscle function," according to Medicine Net.
  
  

Symptoms

• The four common symptoms of Parkinson's Disease are bradykinesia (a slowness in movement); tremors that are usually felt in the hands, arms, legs, jaw and face; rigidity, or stiffness in the arms, legs and trunk; and postural instability (impaired balance and coordination). Other possible symptoms include leg weakness, emotional changes, difficulty swallowing or chewing, difficulty speaking, urinary problems and constipation.
  
  

Causes

• There is no known cause of Parkinson's Disease. However, there are several key factors that may contribute. According to the Mayo Clinic, those factors are genetics, environmental triggers, a lack of dopamine, low norepinephrine levels and the presence of Lewy bodies. "Unusual protein clumps called Lewy bodies are found in the brains of many people with Parkinson's Disease," according to the Mayo Clinic.
  
  

Leg Weakness

• Two of Parkinson's symptoms are tremors and rigidity (stiff muscles). Both can cause leg weakness as the disease progresses. Leg weakness can affect one or both legs. According to Health Hype, leg weakness is vastly different from a general feeling of tiredness or the heavy feeling you get after a long day. "It is the weakened strength of the leg muscles, which is manifested by inability to do certain movements with the foot or leg," the website explains.
  
  Additionally, leg weakness can interfere with walking, as happens with Parkinson's Disease. Because of muscle rigidity and resultant slow movements, Parkinson's sufferers have increasing difficulty in moving parts of their bodies, including the legs. Furthermore, the tremors that occur can also cause weakness in the legs.
  
  

Treatment

• Because there is no cure for Parkinson's Disease, the objective is to control the symptoms. The most common medications in use are Levodopa, Sinemet and Atamet (levodopa and carbidopa). Those afflicted with Parkinson's will also need to make certain lifestyle changes, such as maintaining good nutrition and health, exercising and undergoing physical therapy. While not all Parkinson's sufferers experience leg weakness, it is recommended that railings or banisters be installed around the house to help prevent falls; those afflicted with Parkinson's develop an unusual gait along with rigidity.