Section 9 Movement Disorders

9.1 Limb Movement Disorders

Questions

The Fidgety General

A 58-year-old Air Force general is referred for management of insomnia. He complains of difficulty falling asleep at bedtime, especially when he is flying at night from base to base. He finds that he worries about the various military operations around the world involving the Air Force and he cannot turn his mind off. He has participated in military operations and often thinks about the time when his airplane was hit by antiaircraft fire and he was forced to return to base and make an emergency landing. He also finds that as he is trying to fall asleep in the passenger section he feels fidgety and, to relieve the sensation, he has to get up to walk around. He sometimes has the same sensation when he is acting as a copilot in the cockpit of aircraft. He has had difficulty with sleep for about 30 years but is seeking help now because his inability to sit in the cockpit has worsened recently and he is concerned that he may be developing a serious neurological problem. His mother has the same problem and also has had difficulty with sleep her entire life. He snores his but has never been observed to become apneic. His Epworth Sleepiness Scale score is 2. His BMI is 25. He had a complete physical and screening blood tests 4 months before and was told all of his numbers were normal. He takes low-dose aspirin for heart disease prophylaxis.

1 The differential diagnosis of the insomnia includes each of the following except:

A Posttraumatic stress disorder

B Psychophysiologic insomnia

C Primary restless legs syndrome

D Secondary restless legs syndrome

2 Which one of the following is required to document the diagnosis of restless legs syndrome?

A Nocturnal polysomnogram

B Clinical history alone

C Suggested immobilization test (SIT)

D Serum ferritin

3 The patient brought along the results of the routine blood tests, which are reviewed. Hemoglobin is 13 g/dL, hematocrit is 39%. How do you interpret these results and what do you do next?

A Both results are normal. No further blood tests are warranted

B The hemoglobin is low, but the hematocrit is normal. Vitamin B₁₂ measurement is warranted.

C Both hemoglobin and hematocrit are borderline low but not abnormal enough to be associated with any other abnormality and so no further blood testing is needed.

D Both hemoglobin and hematocrit are below the lower limit of normal. The patient is anemic and thus more testing is required.

4 If it is believed that the patient has secondary RLS, in addition to looking for anemia the patient should be assessed for all of the following except:

A Renal insufficiency

B Neuropathy

C Thyroid disease

D Hepatic failure

5 Because the tests the patient brought in were 4 months old, you decide to order additional tests. Which would you not order?

A Serum ferritin

B Vitamin B₁₂ level

C Stool for occult blood

D Bilirubin and alkaline phosphatase

6 The test results you ordered are as follows: serum ferritin, 6; vitamin B₁₂, 1200; stool for occult blood, positive; bilirubin and alkaline phosphatase, normal. What is the next step?

A Start the patient on a dopaminergic agent.

B Start the patient on ferrous sulfate 50 mg daily.

C Give IM injections of B₁₂.

D Arrange a gastroenterology consultation.

Going Crazy in the MRI Scanner

A 56-year-old woman was referred to the sleep disorders center with a 25-year history of severe insomnia and restlessness at bedtime. The symptoms first began during her last pregnancy. She has a history of depression. Zolpidem was not effective in treating the insomnia. Her family doctor recalled an article in a family practice journal that suggested starting patients on a sedating antidepressant, mirtazapine, for insomnia. He did so. He also prescribed a sustained-release formulation of levodopa for the restlessness. Both medications were taken at bedtime. For the first 8 nights the medications were effective. The restlessness resolved and the patient fell asleep quickly; the patient described the medications as miraculous. The ninth morning the patient noted that she was very restless and had a headache. She was sent for an MRI scan. In the scanner she was so restless when asked to keep still that she started to scream. She was referred to the sleep clinic.

7 What is not a possible explanation of the new symptoms?

A Disease progression

B Augmentation

C Unwanted effect of mirtazapine

D Rebound

8 The next steps should include each of the following except:

A Check serum ferritin.

B Stop mirtazapine.

C Increase dose of levodopa and have it taken 2 hours earlier.

D Stop the levodopa and start on pramipexole or ropinirole.

9 After the medications are changed, the morning symptoms disappear and she is partially improved, but still has significant nighttime symptoms and daytime sleepiness that she would like treated. The following should be considered:

A Start the patient on zolpidem at bedtime.

B Add an opiate such as codeine or methadone at bedtime.

C Start her on modafinil to treat the sleepiness.

D Stop all dopaminergic medications.

Looking for Sleep Apnea, Finding Something Else

A 67-year-old woman, with a BMI of 34 and symptoms of sleep-onset insomnia, early-morning awakening, snoring and, an Epworth Sleepiness Scale score of 9, has a sleep study ordered by her family doctor because of suspected obstructive sleep apnea. Her husband states that she moves the entire night and that it is like sleeping with a twitching fish. In the sleep study the sleep latency was 90 minutes, a value that is typical for this patient. Leg EMG did not show excessive activity during the initial wake period. Total sleep time was 5 hours. A 5-minute fragment of her study is shown in Figure 9.1–1, and the patient had similar findings while she slept the entire night.

FIGURE 9.1–1 Questions 10 to 12.

10 This fragment is consistent with which of the following?

A Obstructive sleep apnea

B Restless legs syndrome

C Periodic limb movements in sleep

D Periodic limb movement disorder

11 Extrapolating from this fragment, what is the periodic limb movement index?

A 5

B 11

C 55

D 132

12 How would you treat this patient’s sleepiness?

A Dopaminergic agent

B Modafinil or armodafinil

C Clonazepam at bedtime

D Treat the insomnia

Right Test for the Wrong Reason

A 45-year-old otherwise healthy woman falls asleep quickly. She wakes up several times during the night, and has symptoms of restlessness in her legs and arms that are relieved by movement. Sometimes she walks to relieve the restlessness in her legs. There is no history of snoring. The Epworth Sleepiness Scale score is 8. The patient states that her family doctor wanted her to have a sleep study because he thought she had restless legs.

13 What should the investigative strategy be and why?

A The patient should have an overnight sleep study because patients with restless legs syndrome have characteristic findings on polysomnography.

B The patient should have an overnight sleep study because she might have upper airway resistance syndrome causing the sleepiness.

C The patient should have a sleep study because she might not have the classic restless legs syndrome but might have another sleep disorder causing awakenings from sleep.

D The patient should not have an overnight sleep study because it is not required in the diagnosis of any movement disorder.

14 The patient has an overnight sleep study; a 2-minute fragment is shown in Figure 9.1–2. What does this fragment show?

A Multiple episodes of hypopnea

B Periodic limb movements without arousals

C Periodic limb movements with arousals

D Diagnostic features of restless legs syndrome

15 The investigation of this patient should include all of the following except:

A Vitamin B₁₂ level

B Vitamin D level

C Serum ferritin

D Complete blood count

16 What is the first line treatment of this patient?

A Dopaminergic agent

B Zolpidem

C Clonazepam at bedtime

D Low-dose opiate at bedtime

FIGURE 9.1–2 Questions 14 to 16.

Answers

1 A. There is nothing in the history that would point toward a diagnosis of posttraumatic stress disorder. Patients with PTSD might complain of insomnia but are troubled by awakenings with recurrent violent dreams. The patient gives a history consistent with restless legs syndrome (RLS), which often is associated with insomnia. Any disorder causing difficulty falling asleep can also lead to psychophysiologic insomnia. It is worth emphasizing that RLS is a syndrome and the ICSD2 has a single RLS entry. There is no specific designation for primary and secondary RLS. ICSD2, p 178

2 B. The diagnosis of RLS in adults only requires a history that is positive for four core characteristics. The mnemonic URGE has been used to help remember them: Urge to move limbs; Rest worsens the sensation; Getting up and moving offers temporary relief; Evening or night worsens the sensation. The polysomnogram is not required in diagnosis, and it should only be done if there is a high probability of a sleep breathing disorder in addition to RLS. The Suggested Immobilization Test has been used in research but is not used in routine clinical assessment. ICSD2, p 180; PPSM5, p 1028

3 D. Normal hemoglobin in men is 14 to 17.5 g/dL. Normal hematocrit in men is 40% to 50%. The reader should be aware of normal values for the most of the routine blood tests. In terms of the relationship between RLS and anemia, it is important to emphasize that nutritional deficiencies can cause secondary RLS (because of a reduction, for example, in CNS iron) before actual anemia is documented. For anemia to be caused by iron deficiency, iron stores in the marrow are zero, not simply reduced. Thus, given these results one would do an anemia workup.

4 D. The disorders that cause secondary RLS generally do not include hepatic failure. The other conditions mentioned have been associated with RLS. One would add to the list unwanted effects of medications. For example, many of the antidepressants (a notable exception is bupropion [Wellbutrin]) may be associated with or cause RLS symptoms. With respect to liver disease, some patients with hemochromatosis develop RLS because they may have low CNS iron levels. However, using iron to treat hemochromatosis can worsen the hemochromatosis. Haba-Rubio et al, 2005

5 D. There is no reason to order bilirubin and alkaline phosphatase, abnormalities of which would indicate liver disease. Serum ferritin would be ordered because low ferritin levels are consistent with reduced iron stores that are a cause of RLS. Because the patient had anemia in the first blood test, a stool for occult blood would be indicated. Vitamin B₁₂ deficiency can cause peripheral neuropathy and RLS. In particular, older patients with pernicious anemia can have RLS. Mold et al, 2004

6 D. The patient has reduced iron stores. The cause of the reduced iron stores must be ascertained. Given the positive stool for occult blood, the next step would be a GI consult. Men and women in the military frequently donate blood, and a history of repeat blood donation has been associated with RLS.

7 A. This is not an example of disease progression. This is a classic description of augmentation and rebound to dopaminergic agents in RLS; however, there is likely a contribution from the mirtazapine. With augmentation there is usually an initial therapeutic benefit, but thereafter there is a worsening of symptoms, with symptoms sometimes exacerbated in other parts of the body not initially affected. Symptoms occur earlier, with rebound movements, and restlessness occurs when the medication wears off, for example, in the morning in this patient. Inexperienced clinicians sometimes increase the dosage of a dopaminergic agent, and the augmentation and rebound simply worsen. Indeed, many family physicians use sedating antidepressants for insomnia based on articles they have read. RLS is a common side effect of second-generation antidepressants; about 25% of patients on mirtazapine develop this symptom. PPSM5, p 1032; Hartmann, 1999; Rottach et al, 2008

8 C. Increasing the dosage of levodopa would be the wrong thing to do. In fact, patients should not be started on levodopa for RLS at all, because the incidence of augmentation is between 30% and 80%, and the rebound in the morning can be quite distressing to patients. Thus the levodopa should simply be stopped, and the patient should be started on either pramipexole or ropinirole. In a patient with nonresponsive RLS one should also always confirm that the serum ferritin level is normal and should stop medications that are known to worsen movements, such as the mirtazapine in this case.

9 B. Opiates can be highly effective in patients with severe RLS and can be added as treatment. Codeine and propoxyphene are generally effective for up to 6 hours. Oxycodone, methadone, and fentanyl patches last longer but are reserved for the more-severe cases. Common side effects of opiates include constipation, daytime sedation, and pruritus. One must always remember that such agents can worsen obstructive apnea.

10 C. This fragment is consistent with periodic limb movements in sleep. There is no evidence for obstructive sleep apnea, and RLS is not diagnosed using a polysomnogram. The term periodic limb movement disorder is reserved for when the periodic limb movements are associated with arousals on EEG. Although the record is compressed, there do not appear to be changes in the EEG that suggest arousals are occurring.

11 D. This fragment shows 11 periodic limb movements in 5 minutes. The index is calculated per hour of sleep, and thus the hour would contain 12 5-minute epochs. The periodic limb movement index would therefore be 12 × 11 = 132.

12 D. Because the patient did not have increased arousals during sleep, it is unlikely that the sleepiness was caused by the periodic limb movements. Thus there is no indication here to use a dopaminergic agent or a stimulant. The pharmacokinetics of clonazepam, if used as a hypnotic, often result in a hangover the next morning. When used as a hypnotic, it is best that clonazepam be taken 1 to 2 hours before bedtime. Given the history and the findings on polysomnography, treating the patient’s insomnia to increase her total sleep time will likely be the most efficacious way to treat the sleepiness.

13 C. The patient should have an overnight sleep study because a movement disorder other than RLS is likely. Periodic limb movements in sleep and periodic limb movement disorder can only be diagnosed by PSG.

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