Musculoskeletal Flashcards
1
Q
Osteogenesis imperfecta (OI), (aka brittle bone disease) is a group of hereditary conditions characterized by
A
abnormal development of type I collagen, a major component of bone matrix but also present in many tissues including skin, joints, and eyes.
2
Q
Four major variants of this disorder are known and associated with .
A
variable severity.
3
Q
Osteogenesis imperfecta
Autosomal dominant (most common) and autosomal recessive forms are seen with
A
multiple bone fractures being the primary associated pathosis.
4
Q
Osteogenesis imperfecta
In the severe forms, extreme bone fragility leads to
A
death in utero or shortly after passage through the birth canal
5
Q
Osteogenesis imperfecta
. In milder forms, the fractures don’t appear until
A
childhood (may be confused with child abuse) and don’t shorten life significantly.
6
Q
Osteogenesis imperfecta
Intermediate forms also are
A
present.
7
Q
Osteogenesis imperfecta
Other interesting but inconsistent findings include
A
blue sclera and opalescent teeth which resemble dentinogenesis imperfecta.
8
Q
Osteogenesis imperfecta
Management includes
A
minimizing factors that cause fractures.
9
Q
Osteogenesis imperfecta
Prognosis depends on the
A
type of OI and expression of the gene.
10
Q
Osteopetrosis (marble bone disease) is a group of rare hereditary disorders characterized by
A
deficient osteoclastic activity with resultant defective bone remodeling.
11
Q
Osteopetrosis
Both autosomal dominant and autosomal recessive forms are seen with an associated
A
variable presentation and severity.
12
Q
Osteopetrosis
Affected patients present with
A
significantly thickened, heavily mineralized and abnormally brittle bone, prone to fractures.
13
Q
Osteopetrosis
Since the marrow space is replaced with
A
dense bone, pancytopenia is common leading to anemia, thrombocytopenia, leukopenia, and an increased prevalence of infections such as osteomyelitis.
14
Q
Osteopetrosis
Compression on the cranial foramina and nerve roots creates
A
nerve palsies (blindness, deafness) in many patients.
15
Q
Osteopetrosis
Because osteoclasts are derived from marrow monocyte precursors, bone marrow transplantation can
A
provide recipients with fully functional osteoclasts.
16
Q
Osteopetrosis
May be complicated by .
A
GVHD
17
Q
Osteoporosis refers to an increased porosity of the .
A
skeleton resulting from reduced bone mass with an associated increased bone fragility and increased prevalence of fractures.
18
Q
Osteoporosis
The process may be
A
localized (such as cases of disuse in an immobilized extremity) or generalized.
19
Q
Osteoporosis
Generalized osteoporosis can arise
A
secondarily to a wide variety of pathoses.
20
Q
Osteoporosis
When primary, the process most commonly is associated with
A
aging and is distinctly common in postmenopausal females with associated reduced estrogen (2-3X more frequent).
21
Q
Osteoporosis
About 25% of women sustain fractures by
A
age 65 and 50% by age 90.
22
Q
Osteoporosis
It is the most common form of
A
acquired, metabolic bone disease (10 million in US, 44 million osteopenia).
23
Q
Osteoporosis
Osteoporotic fractures affect more women than
A
heart attack, stroke and breast cancer combined
24
Q
Osteoporosis
Over 95% of the cases are
A
primary and appear to be related to reduced estrogen in females and lower androgens in males which develop with age.
25
Osteoporosis
Because mechanical forces are known to stimulate bone remodeling, reduced physical activity also is associated with
increased bone losses.
26
Osteoporosis
Other factors thought to be important in osteoporosis are
genetic factors, calcium nutritional state, and secondary causes such as corticosteroid therapy.
27
Osteoporosis
Bone remodeling occurs throughout life; and normally, there is a balance between
bone resorption and apposition.
28
Osteoporosis
It appears there is an age-related decrease in
osteoblastic activity as well as an increase in osteoclastic activity.
29
Osteoporosis
In health, bone formation outpaces resorption until about age
25-30 (time of peak bone mass); followed by a plateau from ages 35-40, with no net gain or loss of bone.
30
Osteoporosis
After age 40, new bone formation does not quite compensate for
bone loss, resulting in a gradual attrition of bones.
31
Osteoporosis
A few years prior to and following menopause, the
imbalance worsens; and although the rate of loss slows the bone density continues to decrease.
32
Osteoporosis
As peak bone mass is generally less in
females, they are typically more vulnerable than men to the impacts of osteopenia/osteoporosis.
33
Osteoporosis:
Although all bones are affected, those containing abundant cancellous bone such as the spine and femoral head demonstrate the
most severe involvement.
34
Osteoporosis
The most common complaint is
bone pain, especially backache, secondary to microfractures and collapse.
Common sites of involvement include the vertebral bodies, pelvis, femoral neck, and other weight-bearing bones.
35
Osteoporosis
Osteoporosis may lead to
kyphoscoliosis and subsequent reduced respiratory function.
36
Osteoporosis
Fracture often follows
trivial trauma.
37
Osteoporosis
Hip fractures result in increased
morbidity and mortality.
Pulmonary embolism and pneumoniae are common complications of
38
Osteoporosis
| Pulmonary embolism and pneumoniae are common complications of
fractures, and result in up to 50K deaths annually.
39
Osteoporosis:
| In the early stages,
standard radiographs are not sufficiently sensitive, but the process can be confirmed by a DEXA (dual-energy x-ray absorptiometry) scan.
40
Osteoporosis:
The primary therapy to slow bone loss includes
adequate dietary calcium intake, vitamin D supplementation, and regular weight-bearing exercise.
41
Osteoporosis:
This approach works best when initiated prior to age
30 to maximize the peak bone mass.
42
Osteoporosis:
The first line of medical therapy for affected patients is the use of
bisphosphonates (E.g. Actonel, Boniva, and Fosamax) due to their ability to reduce osteoclastic activity.
43
Osteoporosis:
Unfortunately, bisphosphonates have been associated with a predisposition to
gnathic osteonecrosis.
44
Osteoporosis:
Other approaches include
estrogen receptor agonists and several newer hormone based drug therapies (E.g. Forteo, Evista) that do not increase the risk for breast and ovarian cancer.
45
Osteoporosis:
New treatment modalities also include
monoclonal antibodies such as Denosumab (Prolia) which acts as a Rank-ligand inhibitor.
46
Paget disease (osteitis deformans) is a fairly common bone disorder characterized by
repetitive episodes of frenzied, regional osteoclastic activity and bone resorption (osteolytic stage), followed by exuberant osteoblastic activity and bone formation (mixed osteoclastic-osteoblastic stage), and finally by an apparent exhaustion of cellular activity (osteosclerotic stage).
47
Paget disease
The net effect is a gain in
bone mass; but the newly formed dense bone is disordered, structurally weak and prone to fracture.
48
Paget disease
These processes produce
skeletal deformation caused by accumulation of excessive amounts of abnormal, unstable bone.
49
Paget disease
The abnormality is rare before the age of
40 and exhibits a slightly increased prevalence in males.
50
Paget disease
There is a marked variation in prevalence in different populations with the pathosis being
rare in individuals from China, Japan, and Africa while affecting up to 10% of the white adult population in many western countries.
51
Paget disease
The lesions may be confined to a
single bone (monostotic, represent ~15%), involve numerous bones (polyostotic, represents ~85%) or rarely the entire skeleton.
52
Paget disease
The etiology is unknown, but
paramyxovirus is suspected.
53
Paget disease
| As mentioned, the process evolves through
three stages.
54
Paget disease
Initially, there is a period of
osteoclastic activity, hypervascularity and bone loss that is followed by a phase of mixed osteoclastic and osteoblastic proliferation which gradually evolves into a late osteosclerotic phase.
55
Paget disease
The typical microscopic features of the disease show
active osteoclastic and osteoblastic activity, many times on the same trabecula of bone.
56
Paget disease
The interstitial tissue is
loosely arranged and highly vascular.
57
Paget disease
The histopathologic features form a
mosaic pattern of bone.
58
Paget disease
Radiographically, the bone shows a mixture of
radiolucent-radiopaque areas referred to as a cotton-wool pattern.
59
Paget disease:
Any bone may be affected. About 80-90% are
asymptomatic, and most are discovered on routine radiographs or blood studies. =
60
Paget disease:
When present, the clinical manifestations and symptoms are
variable and include bone enlargement, bone pain, deformity, cranial nerve compression, hearing loss and visual disturbances, bowing of bones and fractures.
61
Paget disease:
Other possible complications include
leontiasis ossea (lion face, characterized by an overgrowth of the facial and cranial bones) and a slight increased risk (1 % lifetime) for development of sarcomas (particularly osteosarcoma).
62
Paget disease:
The diagnosis is made
secondary to the radiographic and microscopic appearances combined with demonstration of elevated levels of urinary hydroxyproline (⇑bone resorption) and serum alkaline phosphatase (⇑bone apposition).
63
Paget disease:
Most patients have
mild symptoms which can be controlled by calcitonin or bisphosphonates and analgesics.
64
Hyperparathyroidism is characterized by
inappropriate secretion of PTH (parathyroid hormone).
65
Hyperparathyroidism
PTH plays a central role in
calcium homeostasis via its effects on: osteoclast activation, increased calcium resorption by the kidneys, and increased synthesis of vitamin D (kidneys) resulting in increased calcium absorption from the gut.
66
Hyperparathyroidism
The net result is an elevation in
serum calcium.
67
Hyperparathyroidism
Patients often develop
skeletal changes (bone appears ground glass and osteoporotic) due to activation of osteoclasts.
68
Hyperparathyroidism
Osteitis Fibrosa Cystica (cyst-like brown tumors of bone) can also be observed in patients with
hyperparathyroidism. These lesions are histopathologically identical to central giant cell granuloma of the jaws.
69
Primary hyperparathyroidism is one of the most common
endocrine disorders, and it is an important cause of hypercalcemia.
70
Primary hyperparathyroidism
In more than 95% of cases, primary hyperparathyroidism is caused by
parathyroid adenomas or hyperplasia (less commonly by parathyroid carcinoma, but more severe).
71
Primary hyperparathyroidism
Primary hyperparathyroidism is usually a disease of
adults and is more common in women.
72
Primary hyperparathyroidism
The most common manifestation of primary hyperparathyroidism is an increase in
serum calcium due to an increased level of PTH.
73
Primary hyperparathyroidism
Primary hyperparathyroidism has been traditionally associated with a constellation of symptoms that included
"painful bones, renal stones, abdominal groans, and psychic moans".
74
Primary hyperparathyroidism
Pain, secondary to fractures of bones weakened by osteoporosis and resulting from renal stones, with obstructive uropathy, was at one time a
prominent manifestation of primary hyperparathyroidism.
75
Primary hyperparathyroidism
Because serum calcium is now routinely assessed in the
work-up of most patients who need blood tests for unrelated conditions, clinically silent hyperparathyroidism is detected early.
76
Primary hyperparathyroidism
Hence, many of the classic clinical manifestations, particularly those
referable to bone and renal disease are seen much less frequently.
77
Primary hyperparathyroidism
| Treatment involves removal of the
affected gland/tumor.
78
Secondary Hyperparathyroidism is caused by any condition associated with a
chronic depression in the serum calcium level, because low serum calcium leads to compensatory over activity of the parathyroids.
79
Secondary Hyperparathyroidism
Chronic renal insufficiency is associated with
decreased phosphate excretion, which in turn results in hyperphosphatemia.
80
Secondary Hyperparathyroidism
| Renal failure is by far the most common cause of
secondary hyperparathyroidism.
81
Secondary Hyperparathyroidism
The elevated serum phosphate levels directly
depress serum calcium levels and thereby stimulate parathyroid gland activity.
82
Secondary Hyperparathyroidism
In addition, loss of renal substances reduces the synthesis of the active form of
vitamin D, which in turn reduces intestinal absorption of calcium.
83
Secondary Hyperparathyroidism
The clinical manifestations of secondary hyperparathyroidism are generally less severe than the
primary form.
84
Secondary Hyperparathyroidism
The associated renal failure is the
most clinically significant aspect.
85
Secondary hyperparathyroidism:
The treatment of the underlying cause (e.g. renal transplant, Vitamin D supplementation)
will resolve the secondary hyperparathyroidism.
86
Osteomyelitis refers to an
infection spreading through the medullary spaces of a bone.
87
Osteomyelitis
Bacteria can colonize the spaces within bone, normally through one of three pathways.
1. Hematogenous spread
2. Contiguous infection (i.e. odontogenic infections)
3. Direct traumatic introduction (i.e. compound fractures, surgical procedures)
88
Osteomyelitis
Hematogenous osteomyelitis is caused most frequently by
Staphylococcus aureus; while mixed infections, often with anaerobes, are seen in those secondary to trauma or dental problems.
89
Osteomyelitis
Pain and tenderness will be present in the affected area with subsequent development of
redness and swelling in the area.
90
Osteomyelitis
Fever is seen
frequently.
91
Osteomyelitis
Early in the course, radiographic alterations are difficult to ascertain until
significant bone necrosis occurs.
92
Osteomyelitis
With progression,
ill-defined areas of radiolucency develop and may be intermixed with radiopaque sequestra.
93
Osteomyelitis
Treatment may include
drainage and appropriate antibiotics, with or without surgical debridement.
94
Fibrous Dysplasia is characterized by progressive
replacement of normal bone by fibrous tissue intermixed with unorganized, woven bone. This may reflect disordered bone maturation with arrest at an immature stage of woven bone due to a specific mutation.
95
1. Monostotic fibrous dysplasia (single bone):
70% of all cases. It usually manifests in childhood and often becomes stationary at puberty. The most common sites of involvement in descending order of frequency are the ribs, femur, tibia, jaws, calvarium, and humerus.
96
2. Polyostotic fibrous dysplasia without endocrine involvement (Jaffe-Lichtenstein Syndrome):
Multiple bones are affected, and the involvement often tends to be unilateral. This pattern accounts for about 25% of the cases, often arises at an earlier age, and can continue to cause problems during adulthood. Frequently affected bones are craniofacial bones (including jaws), femur, tibia, humerus, and pelvis. Café-au-lait pigmentations are variable but not rare; related endocrine abnormalities are absent.
97
3. Polyostotic fibrous dysplasia in association with endocrinopathies (McCune-Albright syndrome):
This pattern is the least common, represents around 3% of all cases, and typically is accompanied by melanin pigmentation of the skin (café-au-lait spots) and endocrine abnormalities. Although precocious sexual development is the most common endocrine abnormality, other disorders such as hyperthyroidism, excess growth hormone, and primary adrenal hyperplasia may be seen. Females are affected much more than males. The process often is unilateral and affects the majority of the bones on the altered side.
98
Fibrous Dysplasia:
Histopathologic examination of early lesions reveals a mixture of
cellular fibrous connective tissue intermixed with elongated trabeculae of immature woven bone and this pattern has been termed Chinese characters. When radiographically examined with film capable of high detail (dental films), the affected area will appear as an ill-defined area of increased radiopacity described as ground glass. Less detailed radiographs often depict an ill-defined radiolucency.
99
Fibrous Dysplasia
The clinical manifestations and potential of this disease are variable. Swelling and destruction of bone with considerable deformity
can occur. Many cases will stabilize at puberty. Others will progress slowly. Treatment involves surgery and/or close observation. Treatment may vary from observation (May stabilize at puberty), anti-resorptive therapy to surgical reduction (usually delayed until skeletal maturity).
100
A wide variety of benign and malignant tumors of bone can occur. These develop from
bone-producing cells, cartilage-producing cells and interstitial tissue. Bone is also a common site for metastasis of other malignancies. This discussion with focus on one primary bone tumor, osteosarcoma.
101
Osteosarcoma is a bone and osteoid producing
malignancy.
102
Osteosarcoma
Outside of lymphoproliferative diseases, osteosarcoma is the most common
primary malignant tumor of bone.
103
Osteosarcoma
Osteosarcomas occur in all age groups, but most patients are
younger than age 20 (mean age 18yrs).
104
Osteosarcoma
Any bone can be affected, however the
metaphyseal region of long bones in the extremities is the most frequent site (60% occurring in the knee vs 8 % in the jaws).
105
Osteosarcoma
A painful enlarging mass is the
most frequent clinical presentation; however pathologic fracture can also be the first sign of disease.
106
Osteosarcoma
The radiographic appearance is generally that of a
large, destructive, mixed radiolucent-radiopaque lesion that may present with a “sunburst” appearance.
107
Osteosarcoma
| A characteristic feature is the formation of an
acute angle between the neoplastic bone and the cortex (Codman’s triangle).
108
OSteosarcoma
| Diagnosis requires
histologic evidence of direct production of osteoid by malignant mesenchymal cells.
109
Osteosarcoma
| Aggressive surgery and chemotherapy is the standard
treatment and results in a 5 yr survival of 60-70%.
110
Osteosarcoma
| This disease must be treated adequately the
first time because once the patient has a recurrence, survival drops significantly.
111
Osteoarthritis (degenerative joint disease) is the most common disorder of the joints and is a very frequent, if not inevitable, part of aging. The fundamental feature of osteoarthritis is
degeneration of the articular cartilage. The changes that follow in the underlying bone are secondary.
112
Osteoarthritis
The process may be primary --------- or secondary ----------
(arises without obvious predisposing factors)
(arises in a previously deformed joint).
113
Osteoarthritis
In contrast to rheumatoid arthritis, osteoarthritis is not
primarily an inflammation of the joints but may become secondarily inflamed as the process progresses.
114
Osteoarthritis
Although the pathogenesis is unknown, perhaps the most important factors appear to be
aging and mechanical effects. Although osteoarthritis is not exclusively a wear-and-tear process, there is little doubt that mechanical stresses on the joints play a major role in its development.
115
Osteoarthritis
The fundamental feature of osteoarthritis is degeneration of the
articular cartilage; any structural changes in the underlying bone are secondary. Normal articular cartilage is bathed in synovial fluid and ensures a friction-free joint surface.
In addition, the cartilage spreads the load across the joint surface, helping the bone absorb shock and weight without being crushed.
116
Osteoarthritis
| In the early stages, the cartilage cap develops
vertical fissures. With time, these fissures extend through the full thickness to the subchondral bone. Eventually, portions of the cartilage are eroded completely with exposure of the underlying bone. Fragments of dislodged bone and cartilage often float free in the joint space and form “joint mice”. Eventually, the entire surface of the bone becomes exposed, thickened and polished to an ivory-like appearance.
117
Osteoarthritis
At the margins of the joint, small bony outgrowths termed
osteophytes arise and help to further inflame the surrounding synovial membrane.
118
Osteoarthritis
The initial symptoms typically develop after the age of
50 and include crepitus (grating or popping sensation), joint stiffness and deep, aching pain, especially in the morning.
119
Osteoarthritis
Repeated use of the joint tends to
aggravate the pain.
120
Osteoarthritis
The signs and symptoms develop slowly and usually affect only
one or a few joints.
121
Osteoarthritis
As the disease progresses,
pain, deformity and limitations of motion become apparent.
122
Osteoarthritis
In contrast to rheumatoid arthritis, fusion of the joint does not occur. Fortunately, most people are without severe disability. Aside from complete inactivity, there is no way to prevent or halt the progression. Although the process can stabilize, it generally is slowly progressive. Treatment includes
NSAIDs, intrajoint hyaluronic acid, cortisone shots, physical therapy, braces to wear, and joint replacement.
123
Gout is a disorder caused by
tissue accumulation of excessive amounts of uric acid.
124
Gout
High levels of uric acid in these patients can cause
supersaturation of the blood, crystallization of the uric acid and production of recurrent bouts of arthritis.
125
Gout
Elevation of the serum uric acid may result from
overproduction or reduced excretion of uric acid or from both. In most cases, the process is due to an idiopathic overproduction of uric acid.
126
Gout
Whatever the cause, the high uric acid in body fluids leads to
precipitation of urate crystals that trigger a chain of events that culminate in joint injury.
127
Gout
The released crystals activate
complement and cause chemotaxis of neutrophils.
128
Gout
| Dying neutrophils and reacting macrophages release
destructive lysosomal enzymes and inflammatory mediators.
129
Acute gouty arthritis arises upon
precipitation of urate crystals in the synovial fluid and membranes. These crystals elicit an acute inflammatory response until the crystals resolubilize. osteoarthritis.
130
Acute gout
Although any joint may be affected, the
great toe is affected in close to 90%.
131
Acute gout
Peripheral joints like the hands and feet are affected more frequently, most likely
secondary to reduced solubility of urate in these cooler joints.
132
Chronic gouty arthritis arises
secondary to repeated episodes of acute attacks.
133
Chronic gouty arthritis;
| Crystals become
encrusted on the articular surface and even penetrate deeply into surrounding bone and soft tissue. Each deposit is known as a tophus and is diagnostic of gout. Erosion and progressive destruction of the joint occurs secondary to tophi and resembles advanced
134
Gout
After the joints, the -------- is the most frequently affected organ.
kidney
135
Gout
Renal conditions such as pyelonephritis, nephrosclerosis, tubular deposition of crystals, intertubular deposition of crystals and uric acid renal stones are seen
secondary to gout.
136
Gout
Advanced arteriosclerosis, hypertension and obesity also are
positively associated with gout.
137
Gout
Gout exhibits a
male predominance and rarely produces symptoms prior to 30 years of age.
138
Gout
In most cases, the onset of symptoms is
abrupt and followed by asymptomatic intervals and recurrent episodes of arthritis.
139
Gout
With time, increased numbers of joints are
involved with eventual development of permanent joint deformity.
140
Gout
Drugs (NSAIDs, corticosteroids, colchicine, allopurinol) are available to
abort or prevent gout attacks. Diet modification can also aid in management of gout.
141
Duchenne muscular dystrophy
x-linked recessive
142
Duchenne muscular dystrophy:
caused by the absence of a
structuraprotein termed dystrophin and is seen in about 1/3500 live male births.
143
Duchenne muscular dystrophy
Dystrophin attaches portions of the muscle fibers to the
cell membrane, thus playing an important role in the structural and functional integrity of the myocyte.
144
Duchenne muscular dystrophy
Absence or abnormality of dystrophin is associated with
impaired contractile activity and a variety of other derangements in both skeletal and cardiac muscle.
145
Duchenne muscular dystrophy
As would be expected, the disorder is seen predominantly in the
male offspring of carrier females.
146
Duchenne muscular dystrophy
Rare cases occur from
mutations de novo or in females.
147
Duchenne muscular dystrophy
The affected muscles undergo
progressive degeneration, and the process begins in the pelvis and shoulder girdles with eventual spread to the extremities.
148
Duchenne muscular dystrophy
Despite musculature weakness, the leg muscles are
often enlarged secondary to pseudohypertrophy (replacement of lost muscle with fibrofatty tissue).
149
Duchenne muscular dystrophy
The initial signs appear in
childhood and present as difficulty in standing, walking, and getting out of a chair.
150
Duchenne muscular dystrophy
Signs and symptoms typically begin around
three to five years of age. By their teens, most patients are confined to wheel chairs; and death usually ensues before age 30 due to cardiac involvement, weakness of muscles necessary for respiration, or from pneumonia secondary to aspiration of food associated with difficulties in swallowing.
151
Duchenne muscular dystrophy
The diagnosis is confirmed from the
family history, clinical presentation, elevated serum muscle enzymes, by electromyography, and biopsy.
152
Myasthenia gravis is an
autoimmune disease which results in destruction of acetylcholine receptors in the neuromuscular junction and is manifested by weakness and prominent fatigability of voluntary muscles.
153
Myasthenia gravis
The most active muscles generally are the most
severely affected, such as the muscles involved in eye movement, facial expression, chewing, swallowing and respiration.
154
Myasthenia gravis
The disease can arise at any
age and exhibits a female predominance.
155
Myasthenia gravis
Patients with myasthenia gravis exhibit an
increased prevalence of other autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, and Sjögren syndrome.
156
Myasthenia gravis
In addition, there is a strong association with
thymus abnormalities.
157
Myasthenia gravis
Approximately 65% will demonstrate
thymic hyperplasia, while another 15% will exhibit a thymoma.
158
Myasthenia gravis
In both instances, the altered thymus tissue demonstrates
myoid cells which antigenically resemble acetylcholine receptors.
159
Myasthenia gravis
Although the interaction with the thymus is not understood completely, many believe these altered thymus cells stimulate the
development of autoimmunity.
160
Myasthenia gravis
Muscle contraction depends upon a critical number of interactions between acetylcholine and receptors. Myasthenic muscles have about a
70-90% reduction in the number of acetylcholine receptors per neuromuscular junction as compared to controls.
161
Myasthenia gravis
The course and severity of the disease are extremely --------.
variable
162
Myasthenia gravis
The muscle weakness becomes evident with use and typically involves
small, frequently utilized muscles.
163
Myasthenia gravis
The most common sites of initial involvement are the muscles of the
eyelids (ptosis: drooping of eyelids) and the muscles controlling eye movement (diplopia: double vision).
164
Myasthenia gravis
In addition, involvement of the muscles of facial expression, speech and mastication is not
rare. Difficulty in chewing food or holding the head upright is not rare.
165
Myasthenia gravis
The signs and symptoms are first seen as a
failure of contraction after sustained effort; however, this progresses to loss of contractility even after extensive rest.
166
Myasthenia gravis
Weakness worsens with
repeated contractions, and symptoms are worse later in day.
167
Myasthenia gravis
In some patients, the muscular weakness may be confined to a limited number of groups, and the disease is not
progressive and relatively benign. In others, the disorder may be a major threat to life secondary to respiratory compromise and increased susceptibility to pulmonary infections.
168
Myasthenia gravis
The natural course of the condition is improved by
thymectomy in cases of thymus hyperplasia and removal of the tumor in those with a thymoma.
169
Myasthenia gravis
In addition, medications such as
cholinesterase inhibitors and corticosteroids have been proven to be beneficial in many cases.
170
Myasthenia gravis
Some cases of spontaneous remission have been
reported.
171
Myasthenia gravis
In the past, ---------- was a major cause of death; due to improved therapies, the current 5-year survival is ------
respiratory compromise
95%.
