**2.2 Bulbar symptoms**

In about 15% of patients [11] with MG, bulbar symptoms, generally manifested as oropharyngeal muscle weakness, are evident from the beginning [12]; during the course of the disease, bulbar muscle involvement can be found in 60% of patients [3]. The characteristic bulbar symptoms seen in MG include fatigable chewing (particularly solid food) and swallowing (particularly liquids), dysarthria, and inadequate maintenance of the upper airway. Typically, the time needed for eating a meal increases, and conversation becomes difficult, especially while eating [1, 3, 6].

*Dysarthria:* Speech difficulties manifesting as dysarthria and nasality are commonly seen in MG. Initially, dysarthria is an isolated and fluctuating symptom that occurs mostly under the influence of emotions, worsens with prolonged talking, and disappears after a "silent period" [6]. Weakness of laryngeal muscles causes hoarseness; the voice may become weaker in volume, but MG does not determine aphonia [1, 6]. Orbicularis oris weakness is usually observed as the patient becomes unable to whistle, to kiss, and to blow up a balloon or by difficulty in pronouncing certain letters (p, f, s). Importantly, vocal cord paralysis, leading to stridor, or "crowing" during attempted deep inspirations, may be a sign of severe respiratory distress requiring endotracheal intubation [5, 6].

*Dysphagia* in MG is caused by weakness of the lips, the tongue, the masseter, and the pharyngeal muscles or sometimes a combination of these [6]. Dysphagia found in MG patients is typically associated with several characteristic signs as follows: difficulty chewing caused by incomplete jaw closure resulting from masseter and temporalis muscle weakness; difficulty swallowing exposing the patient to a high risk of aspiration, leading to coughing or choking especially while drinking; nasal regurgitation of liquids due to palatal muscle weakness; sensation that food is sticking in the throat as a consequence of upper pharyngeal muscle weakness; and weight loss—which can be correlated with the severity of eating difficulties. It is important to emphasize that dysphagia can precipitate a myasthenic crisis in patients with MG [1, 5, 6].

#### **2.3 Facial appearance**

Myasthenic patients usually have a facial appearance that gives the impression of a sleepy, expressionless, or sad person. This particular appearance is caused mostly by ptosis and facial weakness. Classical features found in MG are also the "myasthenic snarl" and the "rire vertical." These signs occur as attempting to smile produce contraction of the medial part of the upper lip and a horizontal contraction of the corners of the mouth with loss of the natural upward curling and thus, gives the patient's smile the appearance of a sneer. The weakness of the facial muscles usually occurs insidiously and can be asymmetric. Sometimes, a chronic contracted frontalis muscle may give a worried or surprised look to the patient. If weakness is severe, the jaw will tend to hang open and determine the patient to actively hold the mouth closed by sitting with a hand on the chin for support (studious or attentive appearance) [1, 6].

#### **2.4 Limb, trunk, and respiratory weakness**

Any trunk or limb muscle may be involved, but some are more often affected than are others; thus, neck flexors are weaker than neck extensors, and the deltoids, triceps, and extensors of the wrist and fingers and ankle dorsiflexors are usually more affected than other limb muscles. MG limb weakness is mostly proximal and often asymmetric [1, 5]. In MG the arms are typically more affected than the legs; also, in the upper extremities, the extensors are often involved before the flexors, while in the lower extremities, the reverse usually occurs [3, 5].

The main complains of the patients with MG which present weakness of the limbs or trunk muscles include fatigability, unexplained feelings of heaviness, inability to maintain arms at a higher position for a long period of time (i.e., when hanging laundry or washing hair), and difficulty in going up and down the stairs [6].

In some cases, severe weakness of neck extensor muscles leads to difficulty in balancing the head sometimes producing a "dropped head syndrome." Pain in the

**95**

*Clinical Presentation of Myasthenia Gravis DOI: http://dx.doi.org/10.5772/intechopen.86566*

chronic pain [1, 3, 5, 6].

of MG [6, 13].

**3. Physical examination**

elevated after rest [4, 5].

edly without any support, 20 times.

all myasthenic patients [6].

**4. Clinical classification**

subclasses [3, 5] as follows:

other muscle strength is normal.

back and girdle muscles is frequently reported as a natural consequence of the insufficiency of the postural muscles; however, MG is typically not associated with

mechanical ventilation, and nasogastric tube feeding [3].

Respiratory muscle weakness is revealed by limited chest wall movement and manifest use of accessory muscles of respiration. An important diaphragmatic weakness leads to orthopnea compromising the respiratory efficiency when the patient lies supine [4]. Respiratory muscle weakness may cause life-threatening myasthenic crisis with acute respiratory failure requiring immediate intubation,

**Note:** MG is more frequently associated with other autoimmune disease than the general population. Among the autoimmune conditions found in MG patients are hyperthyroidism, rheumatoid arthritis, scleroderma, ulcerative colitis, pernicious anemia, Sjogren's syndrome, and sarcoidosis. Also, autonomic neuropathies, inflammatory myopathies, various autoimmune channelopathies, or acquired neuromyotonia (Isaac's syndrome) may be seen in patients with MG especially if associated with thymoma. Importantly, in MG patients with tachycardia or exophthalmos, a possible hyperthyroidism should always be addressed; it has to be mentioned that, in these cases, weakness may persist despite adequate management

The physical examination should detect fatigable weakness in specific muscle

Diplopia can be demonstrated by having the patient look laterally for about 30 seconds, leading to evident eye muscle fatigue [3]. The lid ptosis can improve by applying cold on the affected eye ("ice pack test"). Also, passively lifting a ptotic lid may cause the opposite lid to fall ("enhanced ptosis") [1]. Cogan's lid twitch—a pathognomic sign in MG—is described as the brief twitch seen in an eyelid that is

A useful functional test for dysarthria implies asking the patient to speak aloud

To test the limb muscle weakness, the patient should be asked to maintain for 3 minutes a horizontally stretched position of arms, hands, and fingers. In patients with MG, this test will lead to shaking or a gradual drooping of arms, hands, or fingers. Also, patients should be able to do knee bends or rise from a chair repeat-

Importantly, vital capacity and peak flow measurements should be assessed in

Several scoring systems of myasthenic signs or the global state of the patient have been proposed including the Osserman classification, myasthenia gravis composite (MGC) scale, and quantitative myasthenia gravis (QMG) score [6]. However, currently the most widely accepted is the MG Foundation of America (MGFA) Clinical Classification which divides MG into five main classes and several

• **Class I**: Any ocular muscle weakness; may have weakness of eye closure. All

groups by repetitive or sustained activity and also again after rest [1, 4].

without interruption producing nasality and/or hoarseness [6].

#### *Clinical Presentation of Myasthenia Gravis DOI: http://dx.doi.org/10.5772/intechopen.86566*

*Thymus*

*Dysarthria:* Speech difficulties manifesting as dysarthria and nasality are commonly seen in MG. Initially, dysarthria is an isolated and fluctuating symptom that occurs mostly under the influence of emotions, worsens with prolonged talking, and disappears after a "silent period" [6]. Weakness of laryngeal muscles causes hoarseness; the voice may become weaker in volume, but MG does not determine aphonia [1, 6]. Orbicularis oris weakness is usually observed as the patient becomes unable to whistle, to kiss, and to blow up a balloon or by difficulty in pronouncing certain letters (p, f, s). Importantly, vocal cord paralysis, leading to stridor, or "crowing" during attempted deep inspirations, may be a sign of severe respiratory

*Dysphagia* in MG is caused by weakness of the lips, the tongue, the masseter, and the pharyngeal muscles or sometimes a combination of these [6]. Dysphagia found in MG patients is typically associated with several characteristic signs as follows: difficulty chewing caused by incomplete jaw closure resulting from masseter and temporalis muscle weakness; difficulty swallowing exposing the patient to a high risk of aspiration, leading to coughing or choking especially while drinking; nasal regurgitation of liquids due to palatal muscle weakness; sensation that food is sticking in the throat as a consequence of upper pharyngeal muscle weakness; and weight loss—which can be correlated with the severity of eating difficulties. It is important to emphasize that dysphagia can precipitate a myasthenic crisis in

Myasthenic patients usually have a facial appearance that gives the impression of a sleepy, expressionless, or sad person. This particular appearance is caused mostly by ptosis and facial weakness. Classical features found in MG are also the "myasthenic snarl" and the "rire vertical." These signs occur as attempting to smile produce contraction of the medial part of the upper lip and a horizontal contraction of the corners of the mouth with loss of the natural upward curling and thus, gives the patient's smile the appearance of a sneer. The weakness of the facial muscles usually occurs insidiously and can be asymmetric. Sometimes, a chronic contracted frontalis muscle may give a worried or surprised look to the patient. If weakness is severe, the jaw will tend to hang open and determine the patient to actively hold the mouth closed by sitting with a hand on the chin for support (studious or attentive

Any trunk or limb muscle may be involved, but some are more often affected than are others; thus, neck flexors are weaker than neck extensors, and the deltoids, triceps, and extensors of the wrist and fingers and ankle dorsiflexors are usually more affected than other limb muscles. MG limb weakness is mostly proximal and often asymmetric [1, 5]. In MG the arms are typically more affected than the legs; also, in the upper extremities, the extensors are often involved before the flexors,

The main complains of the patients with MG which present weakness of the limbs or trunk muscles include fatigability, unexplained feelings of heaviness, inability to maintain arms at a higher position for a long period of time (i.e., when hanging laundry or washing hair), and difficulty in going up and down the

In some cases, severe weakness of neck extensor muscles leads to difficulty in balancing the head sometimes producing a "dropped head syndrome." Pain in the

distress requiring endotracheal intubation [5, 6].

patients with MG [1, 5, 6].

**2.3 Facial appearance**

appearance) [1, 6].

**2.4 Limb, trunk, and respiratory weakness**

while in the lower extremities, the reverse usually occurs [3, 5].

**94**

stairs [6].

back and girdle muscles is frequently reported as a natural consequence of the insufficiency of the postural muscles; however, MG is typically not associated with chronic pain [1, 3, 5, 6].

Respiratory muscle weakness is revealed by limited chest wall movement and manifest use of accessory muscles of respiration. An important diaphragmatic weakness leads to orthopnea compromising the respiratory efficiency when the patient lies supine [4]. Respiratory muscle weakness may cause life-threatening myasthenic crisis with acute respiratory failure requiring immediate intubation, mechanical ventilation, and nasogastric tube feeding [3].

**Note:** MG is more frequently associated with other autoimmune disease than the general population. Among the autoimmune conditions found in MG patients are hyperthyroidism, rheumatoid arthritis, scleroderma, ulcerative colitis, pernicious anemia, Sjogren's syndrome, and sarcoidosis. Also, autonomic neuropathies, inflammatory myopathies, various autoimmune channelopathies, or acquired neuromyotonia (Isaac's syndrome) may be seen in patients with MG especially if associated with thymoma. Importantly, in MG patients with tachycardia or exophthalmos, a possible hyperthyroidism should always be addressed; it has to be mentioned that, in these cases, weakness may persist despite adequate management of MG [6, 13].
