Common neurologic disorders

Below are several common neurologic disorders, along with their causes, pathophysiology, signs and symptoms, diagnostic test findings, treatments, and nursing interventions.

Common neurologic disorders: Myasthenia gravis

Myasthenia gravis produces sporadic but progressive weakness and abnormal fatigue in striated (skeletal) muscles. This weakness and fatigue are exacerbated by exercise and repeated movement but improved by anticholinesterase drugs. Usually, myasthenia gravis affects muscles innervated by the cranial nerves (face, lips, tongue, neck, and throat), but it can affect any muscle group.

Hard to predict

Myasthenia gravis has an unpredictable course that includes periods of exacerbation and remission. There’s no known cure. Drug treatment has improved the prognosis and allows patients to lead relatively normal lives, except during exacerbations. However, if the disease involves the respiratory system, it can be life-threatening. Myasthenia gravis affects 2 to 20 people per 100,000. It’s most common in women between ages 18 and 25 and in men between ages 50 and 60.

What causes it

The cause of myasthenia gravis isn’t known; however, it commonly accompanies autoimmune and thyroid disorders. In fact, 15% of all patients with myasthenia gravis have thymomas.

Pathophysiology

The patient’s blood cells and thymus gland produce antibodies that block, destroy, or weaken the neuroreceptors that transmit nerve impulses, causing a failure in transmission of nerve impulses at the neuromuscular junction. (See What happens in myasthenia gravis.)

What to look for

Common signs of myasthenia gravis include:

  • gradual, progressive skeletal muscle weakness and fatigue that worsens during the day
  • weak eye closure, ptosis, and diplopia
  • blank, masklike facial expression
  • difficulty chewing and swallowing
  • a hanging jaw
  • bobbing motion of the head
  • symptoms of respiratory failure if respiratory muscles are involved

Common neurologic disorders: What happens in myasthenia gravis

Common neurologic disorders

 

What tests tell you

  • The Tensilon test confirms the diagnosis by temporarily improving muscle function after an I.V. injection of edrophonium or neostigmine. Long-standing ocular muscle dysfunction, however, may not respond. This test also differentiates a myasthenic crisis from a cholinergic crisis.
  • Electromyography helps differentiate nerve disorders from muscle disorders.
  • Nerve conduction studies test for receptor antibodies.

How it’s treated

Treatment is symptomatic. Anticholinesterase drugs, such as pyridostigmine (Mestinon), counteract fatigue and muscle weakness and enable about 80% of normal muscle function. However, these measures become less effective as the disease worsens. Corticosteroids may help to relieve symptoms. A patient may undergo plasmapheresis. One with thymomas requires thymectomy, which may lead to remission in adult-onset myasthenia gravis.

 

In a crisis

Acute exacerbations that cause severe respiratory distress necessitate emergency treatment. Tracheotomy, positive-pressure ventilation, and vigorous suctioning to remove secretions usually yield improvement in a matter of days. Anticholinesterase drugs aren’t effective during myasthenic crisis, so they’re discontinued until respiratory function begins to improve. A crisis requires immediate hospitalization and vigorous respiratory support.

What to do

  • Establish an accurate neurologic and respiratory baseline. Help remove secretions as they accumulate. Be alert for signs of an impending crisis (increased muscle weakness, respiratory distress, and difficulty talking or chewing).
  • For the best results, administer drugs at evenly spaced intervals and on time, as ordered. Be prepared to give atropine for anticholinesterase overdose or toxicity.
  • Plan periods of exercise, meals, patient care, and daily activities to take advantage of peaks in the patient’s energy level.
  • Provide soft, solid foods instead of liquids to reduce the risk of choking. Always sit the patient up to eat.
  • Encourage the patient to take an active role in deciding about his care.
  • Evaluate the patient. Look for normal vital signs, evidence of adequate hydration and normal elimination, skin that’s free from sores or problems, and an optimal capacity for activity.
  • Encourage the patient and his family to discuss their feelings, especially feelings of frustration, grief, or loss. Listen and provide emotional support. (See Myasthenia gravis teaching tips.)

Common neurologic disorders: Myasthenia gravis teaching tips

  • Help the patient plan daily activities to coincide with energy peaks. Stress the need for frequent rest periods throughout the day. Emphasize that periodic remissions, exacerbations, and day-to-day fluctuations are common.
  • Teach the patient how to recognize adverse effects and signs of toxicity of anticholinesterase drugs (headaches, weakness, sweating, abdominal cramps, nausea, vomiting, diarrhea, excessive salivation, bronchospasm) and corticosteroids. Warn him to avoid strenuous exercise, stress, infection, and unnecessary exposure to the sun or cold weather. Caution him to avoid taking other medications without consulting his primary health care provider.
  • Refer the patient to the Myasthenia Gravis Foundation for more information.
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Common neurologic disorders: Parkinson’s disease

Parkinson’s disease, a slowly progressive and degenerative disorder, is one of the most common neurologic disorders in the United States. Parkinson’s disease may appear at any age; however, it’s rare in people younger than age 30 and risk increases with age. Parkinson’s disease most commonly affects men, and strikes 1 out of every 100 people older than age 60.

What causes it

In most instances, the cause of Parkinson’s disease isn’t known. However, some cases result from exposure to toxins, such as manganese dust and carbon monoxide, that destroy cells in the substantia nigra of the brain.

Pathophysiology

Parkinson’s disease affects the extrapyramidal system, which influences the initiation, modulation, and completion of movement. The extrapyramidal system includes the corpus striatum, globus pallidus, and substantia nigra. In Parkinson’s disease, a dopamine deficiency occurs in the basal ganglia, the dopamine-releasing pathway that connects the substantia nigra to the corpus striatum. Reduction of dopamine in the corpus striatum upsets the normal balance between the dopamine (inhibitory) and acetylcholine (excitatory) neurotransmitters. Symptoms occur when affected brain cells can no longer perform their normal inhibitory function within the CNS.

What to look for

  • Insidious tremor that begins in the fingers (unilateral pill-roll tremor), increases during stress or anxiety, and decreases with purposeful movement and sleep
  • Muscle rigidity that resists passive muscle stretching; it may be uniform (lead-pipe rigidity) or jerky (cogwheel rigidity)
  • Difficulty walking (gait lacks normal parallel motion and may be retropulsive or propulsive)
  • Bradykinesia or slowing of muscle movements
  • High-pitched monotone voice
  • Drooling and dysphagia
  • Mask-like facial expression, poor blink reflex, and wide-open eyes
  • Loss of postural control (body bent forward while walking)
  • Slowed, monotonous, slurred speech that may become severely dysarthric
  • Oculogyric crises (eyes are fixed upward, with involuntary tonic movements) and, occasionally, blepharospasm

What tests tell you

Laboratory test results rarely identify Parkinson’s disease. Consequently, diagnosis depends on the patient’s age, health history, and presence of characteristic signs of disease. However, urinalysis may reveal decreased dopamine levels, and CT scan or MRI may help rule out other disorders such as an intracranial tumor.

How it’s treated

There’s no known cure for Parkinson’s disease. Treatment focuses on relieving symptoms and maintaining as high a level of function as possible for as long as possible. Drug therapy and physical therapy are the modes of treatment. In severe disease, stereotactic neurosurgery may be used.

Levodopa — with or without the carbs

Typical drug therapy includes levodopa (Dopar), a dopamine replacement that’s most effective in the early stages. Levodopa can cause significant adverse reactions, so it’s frequently given in combination with carbidopa, which halts peripheral dopamine synthesis. If carbidopa/levodopa (Sinemet) proves ineffective or too toxic, alternative drug therapy may include:

  • dopamine agonists, such as bromocriptine (Parlodel), pramipexole (Mirapex), or ropinirole (Requip)
  • anticholinergics such as trihexyphenidyl
  • antihistamines such as diphenhydramine (Benadryl)
  • amantadine (Symmetrel), an antiviral agent
  • selegiline, an enzyme inhibitor.

A class by itself

A new class of drugs, catechol-O-methyltransferase (COMT) inhibitors (tolcapone [Tasmar]), which are combined with levodopa, are achieving some measure of success in prolonging relief from symptoms. These drugs block the enzyme that breaks down levodopa before it enters the brain. This enhances and prolongs the effect of levodopa. In younger patients, dopamine agonists may be used before COMT inhibitors. Unfortunately, prolonged use of any drug tends to reduce its effectiveness.

In stereo

If drug therapy fails, stereotactic neurosurgery may offer a viable alternative. This procedure interrupts the function of the subthalamic nucleus, the pallidum, or the ventrolateral nucleus of the thalamus to prevent involuntary movement. This treatment is most effective in younger and otherwise healthy patients who have unilateral tremor or muscle rigidity. Neurosurgery is a palliative measure that can only relieve symptoms, not reverse the disease.

One deep brain

In some cases, deep brain stimulation is used to stop uncontrolled movements. The surgeon places electrodes in the thalamus or globus pallidus. Leads connect the electrodes to a device that the patient can activate when symptoms occur.

Get physical

Physical therapy complements drug treatment and neurosurgery to maintain normal muscle tone and function. Typically, physical therapy includes active and passive ROM exercises, routine daily activities, walking, and baths and massage to help relax muscles.

What to do

  • If the patient has had surgery, monitor his LOC and vital signs closely for hemorrhage or increased ICP.
  • Encourage independence. A patient with excessive tremor may have better control if he sits in a chair and uses the chair’s arms to steady himself. Remember that fatigue can exacerbate symptoms and, in turn, increase the patient’s dependence on others.
  • Establish a regular bowel routine by encouraging the patient to drink 2 qt (2 L) of liquid daily and eat high-fiber foods. An elevated toilet seat can make it easier to transition from standing to sitting.
  • Encourage the patient to remain as active as possible. The disease progresses more slowly in those who stay active.
  • Encourage the patient and his family to ask questions. Listen to their concerns and provide succinct, accurate answers.
  • Evaluate the patient. Optimal oxygen saturation levels will indicate adequate respiratory function. He should have normal urinary function and be free from UTI. In addition, he should perform normal daily activities within the limits imposed by his condition. The patient and his family should understand Par kin son’s disease and its treatment. (See Parkinson’s disease teaching tips.)

Common neurologic disorders: Parkinson’s disease teaching tips

  • Teach the patient and family about the disease, its possible progressive stages, therapeutic management, and prevention of complications and injuries.
  • Instruct the patient on his drug therapy and the relationship of drug administration to diet and food intake if he’s taking levodopa. Caution him that drugs for Parkinson’s disease commonly interact with medications taken for many other conditions.
  • Encourage exercise, maximal independence in activities of daily living, and physical and occupational therapy to maintain muscle strength.
  • Refer the patient and family to the National Parkinson Foundation or the United Parkinson Foundation for more information.
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