Peripheral Nerve and Muscle Disease (What Do I Do Now)

SECTION I – NEUROPATHY
1. Small Fiber Neuropathy 3
Small fi ber neuropathy may present in an atypical pattern of asymmetric sensory
symptoms. Nerve conduction studies are usually normal since this disorder aff ects
the smaller unmyelinated fi bers. Impaired glucose tolerance can be an etiological
factor. Rational pain treatment for this condition is outlined.
2. Multifocal Motor Neuropathy 10
Multifocal motor neuropathy (MMN) may be mistaken for common entrapment
neuropathies, although absence of signifi cant sensory fi ndings is a helpful clue to
the diagnosis. MMN may also mimic motor neuron disease. Th e clinical features,
diff erential diagnosis, investigations, and treatment options are described in this
chapter.
3. Diagnosis of Amyotrophic Lateral Sclerosis 15
Early in its course, amyotrophic lateral sclerosis (ALS) is mistaken for a number
of other neuromuscular problems, including spinal disease, multifocal motor
neuropathy, and even carpal tunnel syndrome, particularly when the onset of
weakness is focal. Later, of course, the presentation is pathognomonic. Th e
diff erential diagnosis of focal weakness is discussed as well as recognition of the
more typical ALS clinical syndrome.
4. Amyotrophic Lateral Sclerosis Ethical Issues and Management 23
Treatment issues are discussed in the setting of a very challenging patient with
amyotrophic lateral sclerosis with frontotemporal dementia, including
management of neurological symptoms and cognitive dysfunction. Ethical issues
are analyzed in this case as well.
5. Arsenic Neuropathy 30
A patient presents with a sensorimotor neuropathy and believes he has been
poisoned. Th e approach to the diff erential diagnosis of arsenic toxicity is
presented. Comparisons with mimics of this entity are made, and clinical clues to
its early detection are provided.
6. Diagnosis of Guillain-Barré Syndrome 37
Guillain Barré syndrome may present in several ways and the diff erential
diagnosis may be extensive. Th is chapter discusses the clinical features and
diagnostic considerations of this important condition.
7. Management of Guillain-Barré Syndrome 43
Management of Guillain-Barré syndrome involves several factors. Th is chapter
discusses an approach to treatment which includes role of respiratory and
autonomic monitoring as well as the immunotherapy considerations.
8. Chemotherapy-Induced Peripheral Neuropathy 48
Infection with HIV and lymphoma predispose patients to peripheral neuropathy
via a number of mechanisms. Possible causes of peripheral neuropathy in this
situation are discussed. Chemotherapy-induced peripheral neuropathy may have
distinct features.
9. Idiopathic Brachial Neuritis 55
Severe shoulder pain in the absence of a clear orthopedic cause may be due to
acute brachial plexitis. It is important not to misdiagnose this condition. Th e
approach to diagnosis and treatment are discussed.
10. Hereditary Neuropathy 60
Hereditary neuropathies are common. Th ey are often diagnosed when another
medical issue begins, for example, orthopedic foot problems or chemotherapy
which causes a persistent severe neuropathy. It is important to obtain a very detailed
family history for diagnosis. Genetic testing can be helpful in selected cases.
11. Critical Illness Neuropathy 69
Neuromuscular disorders are important causes of newly acquired weakness in the
ICU. It is important to obtain a complete past medical history since preexisting
medical conditions may play a role. Th e diagnosis and prognosis of critical illness
neuromyopathy are discussed in the context of a critical care patient with severe
weakness.
12. Chronic Infl ammatory Demyelinating Polyneuropathy 75
Chronic infl ammatory demyelinating polyneuropathy typically presents with
both proximal and distal weakness, arefl exia, and distal sensory fi ndings. Th is
chapter emphasizes the importance of diff erential diagnosis and work up.
Treatment options are also described.
13. Nutritional Neuropathies 81
A number of nutritional causes of peripheral neuropathy have been identifi ed.
Patients who have gastrointestinal disease or who have undergone bariatric surgery
are at risk, although frequently the specifi c cause is not ascertained. Vitamin B 12
and thiamine defi ciencies are the most common in bariatric surgery patients.
14. Pyridoxine Toxicity 88
Vitamin therapy is considered to be safe, but in the case of pyridoxine neuropathy
this is untrue. Th e typical presentation involving progressive and severe balance
problems with a loss of limb coordination is described in this case. Th e diagnosis
and treatment are outlined.
15. Vasculitic Neuropathy 94
Th is chapter emphasizes the diagnostic considerations of vasculitic neuropathy,
which includes the signifi cant limitations of serologic markers in non-systemic
vasculitic neuropathy. Keys to management are also reviewed.
16. Piriformis Syndrome 98
Th is somewhat controversial syndrome is discussed via a presentation involving
progressive posttraumatic buttock and leg pain, along with numbness. Newer
imaging techniques may be an important factor in diagnosing this condition in
the future. Th e diagnosis and treatment of piriformis syndrome (a cause of
extraspinal sciatica) are discussed.
SECTION II – MYOPATHY
17. Myotonic Dystrophy 107
Myotonic dystrophy commonly presents later in life. It aff ects multiple organ
systems and is associated with cardiac, endocrine, and ophthalmological
disorders. Cognitive impairment can also be a prominent feature. Diagnosis and
management of this disorder is discussed.
18. Metabolic Myopathy 113
A metabolic myopathy may be an overlooked etiology of recurrent exercised
induced weakness. Th is chapter discusses the clinical features and diagnostic
considerations for adult patients with suspected metabolic myopathy.
19. Infl ammatory Myopathy 119
An infl ammatory myopathy presentation is often straight-forward to recognize;
however careful evaluation is needed to make a specifi c diagnosis. Th is chapter
discusses the clinical features, diff erential diagnosis, investigations, and
management of polymyositis, dermatomyositis, and (the often overlooked)
inclusion body myositis.
20. Periodic Paralysis 126
Acute stiff ness and weakness presenting after exercise are suggestive of several
diagnoses. Knowledge of diet, activity, family history, and clinical
neurophysiology can provide important clues to the diagnosis of periodic
paralysis. Th e clinical picture, laboratory investigation, and treatment of this
condition are presented.
21. Statin Myopathy 133
Statin myopathy can occur at anytime during use. Th is chapter discusses
an approach to diagnosis, and emphasizes management considerations;
which include awareness of statin metabolism by the cytochrome
P450 system.
22. Limb-Girdle Muscular Dystrophy 138
Slow progression of proximal weakness in an adult may suggest Becker muscular
dystrophy but limb girdle muscular dystrophy needs to be considered. Th is
chapter discusses a diagnostic approach which includes the utility of ever evolving
genetic tests. Management considerations are also outlined.
23. Cramps 143
Muscle cramps are a common complaint. When not associated with weakness,
the course is usually benign but still frustrating to patients. Not always will a
specifi c cause be discovered. Etiology and treatment of this are presented.
SECTION III – NEUROMUSCULAR JUNCTION AND AUTONOMIC NEUROPATHY
24. Myasthenia Gravis 151
Fatigable weakness is the hallmark of myasthenia gravis. It may present with false
localizing signs; the physician incorrectly diagnoses a brainstem stroke.
Laboratory examinations have greatly assisted in diagnostic acumen.
25. Treatment of Myasthenic Crisis 156
In myasthenia gravis, weakness and respiratory insuffi ciency can occur quickly.
It is important for the treating physician to recognize this and institute treatment
rapidly. Diff erentiation of myasthenic crisis from cholinergic crisis is explained, as
well as treatment strategies for myasthenic crisis.
26. Diagnosis of Autonomic Neuropathy 161
Syncope in a patient with orthostatic hypotension may indicate autonomic
dysfunction. A number of disorders may be associated with autonomic
neuropathy. Autonomic testing and serological testing may assist in diagnosis.
27. Management of Autonomic Neuropathy 168
Th e management of orthostatic hypotension in autonomic neuropathy can be
vexing. Newer treatment strategies, including the use of pyridostigmine, may be
very helpful. Gastrointestinal symptoms are important to eff ectively manage in
diabetics since glucose control can be adversely aff ected.