Skip to document
Welcome to StudocuSign in to access the best study resources
Guest user
0followers
HomeMy LibraryAsk AI
  • You don't have any recent items yet.
My Library
  • You don't have any courses yet.
  • You don't have any books yet.
  • You don't have any Studylists yet.

Syndromes Caused by Weak Muscles

Syndromes Caused by Weak Muscles
Course

Clinical Exposure in Mental Health (OT2316L)

6 Documents
Students shared 6 documents in this course
Academic year: 2022/2023
Listed bookSynopsis of Psychiatry: Behavioral Sciences/Clinical Psychiatry
Uploaded by:
Anonymous Student
This document has been uploaded by a student, just like you, who decided to remain anonymous.
University of Perpetual Help System DALTA

Comments

Please sign in or register to post comments.

Students also viewed

Related documents

Preview text

SYNDROMES CAUSED BY WEAK MUSCLES

Weakness implies that a muscle cannot exert normal force. Neurologists use the words paralysis or plegia to imply total loss of contractility; anything less than total loss is paresis. In practice, however, someone may mention a partial hemiplegia, which conveys the idea even if it is internally inconsistent. Hemiplegia implies weakness of an arm and leg on the same side. Crossed hemiplegia is a confusing term, generally implying unilateral cranial nerve signs and hemiplegia on the other side, a pattern seen with brainstem lesions above the decussation of the corticospinal tracts. Monoplegia is weakness of one limb; paraplegia means weakness of both legs.

This content describes syndromes that result from pathologically weak muscles, so that a student new to neurology can find the sections of the book that describe specific diseases. There is more than one approach to this problem, because no single approach is completely satisfactory. Elaborate algorithms have been devised, but the flowchart may be too complicated to be useful unless it is run by a computer. It may be simpler to determine first whether there is pathologic weakness, then to find evidence of specific syndromes that depend on recognition of the following characteristics: distribution of weakness, associated neurologic abnormalities, tempo of disease, genetics, and patient age.

RECOGNITION OF WEAKNESS OR PSEUDOWEAKNESS

Patients with weak muscles do not often use the word <weakness= to describe their symptoms. Rather, they complain that they cannot climb stairs, rise from chairs, or run or that they note foot drop (and may actually use that term). They may have difficulty turning keys or doorknobs. If proximal arm muscles are affected, lifting packages, combing hair, or working overhead may be difficult. Weakness of cranial muscles causes ptosis of the eyelids, diplopia, dysarthria, dysphagia, or the cosmetic distortion of facial paralysis. These specific symptoms will be analysed later. Some people use the word <weakness= when there is no neurologic abnormality. For instance, aging athletes may find that they can no longer match the achievements of youth, but that is not pathologic weakness.

Weakness in a professional athlete causes the same symptoms that are recognized by other people when the disorder interferes with the conventional activities of daily life. Losing a championship race, running a mile in more than 4 minutes, or jogging only 5 miles instead of a customary 10 miles are not symptoms of diseased muscles. Others who lack the specific symptoms of weakness may describe "chronic fatigue. "They cannot do housework; they have to lie down to rest after the briefest exertion. If they plan an activity in the evening, they may spend the entire day resting in advance. Employment may be in jeopardy. Myalgia is a common component of this syndrome, and there is usually evidence of depression. The chronic fatigue syndrome affects millions of people and is a major public health problem. Vast research investments have been made to evaluate possible viral, immune, endocrine, autonomic, metabolic, and other factors, none, however, seems a consistent as depression and psychosocial

causes. It is not, some put it, a "diagnosis of exclusion." Instead, the characteristic history is recognizable, and on examination there is no limb weakness or reflex alteration. Fading athletes and depressed, tired people with aching limbs have different emotional problems, but both groups lack the specific symptoms of muscle weakness, and the share two other characteristics: No abnormality appears on neurologic examination, and no true weakness is evident on manual muscle examination. That is, there is no weakness unless the examiner uses brute force. A vigorous young adult examiner may outwrestle a frail octogenarian, but that does not imply pathologic weakness in the loser. Students and residents must use reasonable force in tests of strength against resistance. Fatigue and similar symptoms may sometimes be manifestations of systemic illness due to anemia, hypoventilation, congestive heart failure with hypoxemia and hypercapnia, cancer, of systemic infection. There is usually other evidence of the under lying disease, however, and that syndrome is almost never m taken for a neurologic disorder. Other patients have pseudo weakness. For instance, some patients attribute a gait disorder to weak legs, but it is immediate apparent on examination or even before formal examination da they have parkinsonism. Or a patient with peripheral neurons thy may have difficulty with fine movements of the fingers because of weakness but because of severe sensory loss. Or a patient may have difficulty raising one or both arms because of sitis, not limb weakness. Or a patient with arthritis may be luctant to move a painful joint. Finally, examination may uncover patients with pseudo weakness that may be due to deceit, deliberate or otherwise. Hysteric patients and Munchausen deceivers or other malingerers who feign weakness all lack specific symptoms. Or they may betray inconsistencies in the history because they can participate in some activities but not in others that involve the same muscles. On examination, their dress, cosmetic facial makeup, and behavior may be histrionic. In walking, they may stagger dramatically, but they do not fall or injure themselves by bumping into furniture. In manual muscle tests, they abruptly give way, or they shudder in tremor rather than apply constant pressure. Misdirection of effort is one way to describe that behavior. Some simply refuse to participate in the test. The extent of disorder may be surprising, however. I and others have seen psychogenic impairment of breathing that led to use of a mechanical ventilator.

PATTERNS OF WEAKNESS

In analyzing syndromes of weakness, the examiner uses several sources of information for the differential diagnosis. The pattern of weakness and associated neurologic signs delimit some of the anatomic possibilities to answer the question of where the lesion is located. Patient age and the tempo of evolution aid in deciding what the lesion is the differential diagnosis of weakness encompasses much of clinical neurology, so the reader will be referred to other sections for some of the review. For instance, the first task in the analysis of a weak limb is to determine whether the condition is due to a lesion of the upper or lower motor neuron, a distinction that is made on the basis of clinical findings.

Overactive tendon reflexes with clonus, Hoffmann signs, and Babinski signs denote an upper motor neuron disorder. Lower motor neuron signs include muscle weakness, wasting, and

sclerosis (with or without upper motor neuron signs in the legs). The arms hang limply at the side while the patient walks with normal movements of the legs. Similar patterns may be seen in some patients with myopathy of unusual distribution. It is difficult to understand how a cerebral lesion could cause weakness of the arms without equally severe weakness of the legs, but this <man-in- the-barrel syndrome= is seen in comatose patients who survive about of severe hypertension.

Monomelic Paresis

If one leg or one arm is weak, the presence of pain in the low back or the neck may point to a compressive lesion. Whether acute or chronic, herniated nucleus pulposus is high on the list of possibilities if radicular pain is present. Acute brachial plexus neuritis (neuralgic amyotrophy) is another cause of weakness in one limb with pain; a corresponding syndrome of the lumbosacral plexus is much less common. Peripheral nerve entrapment syndromes may also cause monomelic weakness. Pain, but the pain is local, not radicular.

Mononeuritis multiplex may also cause local pain, paresthesia, and paresis. In painless syndromes of isolated limb weakness in adults, mo tor neuron disease is an important consideration if there is no sensory loss. Sometimes, in evaluating a limb with weak, wasted, and fasciculating muscle, the examiner is surprised because tendon reflexes are preserved or even overactive, instead of being lost. This apparent paradox implies lesions of both upper and lower motor neurons, almost pathognomonic of amyotrophic lateral sclerosis. The signs may be asymmetric in early stages of the disease. Although rare, it is theoretically possible for strokes or other cerebral lesions to cause monomelic weakness with upper motor neuron signs. Weakness due to a cerebral lesion may be more profound in the arm, but abnormal signs are almost always present in the leg, too; that is, the syndrome is really a hemiparesis.

Neck Weakness

Difficulty holding up the head is seen in some patients with diseases of the motor unit, probably never in patients with upper motor neuron disorders. Usually, patients with neck weakness also have symptoms of disorder of the lower cranial nerves (dysarthria and dysphagia) and often also of adjacent cervical segments, as manifest by difficulty raising the arms. Amyotrophic lateral sclerosis and myasthenia gravis are probably the two most common causes. Rarely, there is isolated weakness of neck muscles, with difficulty holding the head up, but no oropharyngeal or arm symptoms.

This floppy head syndrome or dropped head syndrome is a disabling disorder that is usually due to one of three conditions: motor neuron disease, myasthenia gravis, or polymyositis. I have seen one such patient with a Chiari malformation. Some cases, however, are idiopathic. New terms have been introduced to explain this syndrome: the bent spine syndrome and isolated myopathy of the cervical extensor muscles, which may be variations of the same condition. EMG shows a myopathic pattern in affected paraspinal muscles, and MRI may show replacement of muscle by fat in cervical, thoracic, or both areas.

Weakness of Cranial Muscles

The major problems in differential diagnosis involve the site of local lesions that affect individual nerves of ocular movement, facial paralysis, or the vocal cords. Pseudobulbar palsy due to upper motor neuron lesions must be distinguished from bulbar palsy due to lower motor neuron disease and then almost always a form of amyotrophic lateral sclerosis. This distinction depends on associated signs of upper or lower motor neuron lesions. Myasthenia gravis can affect the eyes, face, or oropharynx (but only exceptionally the vocal cords); in fact, the diagnosis of myasthenia gravis is doubtful if there are no cranial symptoms. Brainstem syndromes in the aging population may be due to stroke, meningeal carcinomatosis, or brainstem encephalitis.

Was this document helpful?

Syndromes Caused by Weak Muscles

Course: Clinical Exposure in Mental Health (OT2316L)

6 Documents
Students shared 6 documents in this course

University: University of Perpetual Help System DALTA

Was this document helpful?
SYNDROMES CAUSED BY WEAK MUSCLES
Weakness implies that a muscle cannot exert normal force. Neurologists use the words paralysis
or plegia to imply total loss of contractility; anything less than total loss is paresis. In practice,
however, someone may mention a partial hemiplegia, which conveys the idea even if it is
internally inconsistent. Hemiplegia implies weakness of an arm and leg on the same side. Crossed
hemiplegia is a confusing term, generally implying unilateral cranial nerve signs and hemiplegia
on the other side, a pattern seen with brainstem lesions above the decussation of the
corticospinal tracts. Monoplegia is weakness of one limb; paraplegia means weakness of both
legs.
This content describes syndromes that result from pathologically weak muscles, so that a student
new to neurology can find the sections of the book that describe specific diseases. There is more
than one approach to this problem, because no single approach is completely satisfactory.
Elaborate algorithms have been devised, but the flowchart may be too complicated to be useful
unless it is run by a computer. It may be simpler to determine first whether there is pathologic
weakness, then to find evidence of specific syndromes that depend on recognition of the
following characteristics: distribution of weakness, associated neurologic abnormalities, tempo
of disease, genetics, and patient age.
RECOGNITION OF WEAKNESS OR PSEUDOWEAKNESS
Patients with weak muscles do not often use the word <weakness= to describe their symptoms.
Rather, they complain that they cannot climb stairs, rise from chairs, or run or that they note foot
drop (and may actually use that term). They may have difficulty turning keys or doorknobs. If
proximal arm muscles are affected, lifting packages, combing hair, or working overhead may be
difficult. Weakness of cranial muscles causes ptosis of the eyelids, diplopia, dysarthria, dysphagia,
or the cosmetic distortion of facial paralysis. These specific symptoms will be analysed later.
Some people use the word <weakness= when there is no neurologic abnormality. For instance,
aging athletes may find that they can no longer match the achievements of youth, but that is not
pathologic weakness.
Weakness in a professional athlete causes the same symptoms that are recognized by other
people when the disorder interferes with the conventional activities of daily life. Losing a
championship race, running a mile in more than 4 minutes, or jogging only 5 miles instead of a
customary 10 miles are not symptoms of diseased muscles. Others who lack the specific
symptoms of weakness may describe "chronic fatigue. "They cannot do housework; they have to
lie down to rest after the briefest exertion. If they plan an activity in the evening, they may spend
the entire day resting in advance. Employment may be in jeopardy. Myalgia is a common
component of this syndrome, and there is usually evidence of depression. The chronic fatigue
syndrome affects millions of people and is a major public health problem. Vast research
investments have been made to evaluate possible viral, immune, endocrine, autonomic,
metabolic, and other factors, none, however, seems a consistent as depression and psychosocial

Students also viewed

Related documents