Common symptoms include muscle weakness, cramps, stiffness, and tetany.

Myopathies in systemic disease results from several different disease processes including endocrine, inflammatory, paraneoplastic, infectious, drug- and toxin-induced, critical illness myopathy, metabolic, collagen related, and myopathies with other systemic disorders. Patients with systemic myopathies often present acutely or sub acutely. On the other hand, familial myopathies or dystrophies generally present in a chronic fashion with exceptions of metabolic myopathies where symptoms on occasion can be precipitated acutely. Most of the inflammatory myopathies can have a chance association with malignant lesions; the incidence appears to be specifically increased only in patients with dermatomyositis.

There are many types of myopathy. ICD-10 codes are provided here where available.

Patients with acquired non-inflammatory myopathy typically experience weakness, cramping, stiffness, and tetany, most commonly in skeletal muscle surrounding the limbs and upper shoulder girdle.

The most commonly reported symptoms are:

- Muscle fatigue

- Pain

- Muscle spasms and cramps

- Tingling

- Numbness

- Tetany

- Loss of coordination and balance

- Lack of fine and gross motor control

- Muscular wasting and atrophy

Some early signs of HIBMs includes:

- Difficulty walking on heels, and difficulty running;

- Weak index finger;

- Frequent loss of balance.

- On muscle biopsy, the typical finding includes inclusion bodies, rimmed vacuoles and accumulation of aberrant proteins similar to those found in senile plaques of Alzheimer's disease (amyloid beta, hyperphosphorylated tau, amongst others)

Multicore myopathy, also referred to as minicore myopathy, is associated with small areas of decreased oxidative activities, resulting in areas that appear in this histology as “cores”. These appear through microscopy very similar to central core, however the cores are typically smaller in multicore myopathy. As with congenital fiber type disproportion, patients have a greater number of type 1 fibers. Overall, approximately half of diagnosed individuals report no progression of muscle weakness, while half report a very slow progression.

Congenital fiber type disproportion affects skeletal muscle, typically causing weakness in the shoulders, upper arms, thighs, and hips. Skeletal muscle is made up of two kinds of fiber, type 1 and type 2. In congenital fiber type disproportion, type 1 fibers are not only smaller but often more abundant than type 2 fibers. This leads to affected individuals being able to maintain an active lifestyle, though they usually have lower levels of stamina.

Severity with this disease varies greatly, but people typically present symptoms by the age of one. Individuals do not usually worsen with time, and cases have even been reported of improvements.

Hereditary inclusion body myopathies (HIBM) are a heterogeneous group of very rare genetic disorders which have different symptoms. Generally, they are neuromuscular disorders characterized by muscle weakness developing in young adults. Hereditary inclusion body myopathies comprise both autosomal recessive and autosomal dominant muscle disorders that have a variable expression (phenotype) in individuals, but all share similar structural features in the muscles.

HIBMs are a group of muscle wasting disorders, which are uncommon in the general world population. One autosomal recessive form of HIBM is known as IBM2 or GNE myopathy, which is a common genetic disorder amongst people of Iranian Jewish descent. IBM2 has also been identified in other minorities throughout the world, including people of Asian (Japanese and others), European, and South American origin, as well as Muslim people in the Middle Eastern, Palestinian, and Iranian origin. In Japan and many East Asian countries, this disorder is known as Distal Myopathy with Rimmed Vacuoles (DMRV).

IBM2 causes progressive muscle weakness and wasting. Muscle wasting usually starts around the age of 20 – 30 years, although young onset at 17 and old onset at 52 has been recorded. As such, it affects the most productive times of our lives. It can progress to marked disability within 10 – 15 years, confining many people with IBM2 to a wheelchair. The weakness and severity can vary from person to person. In some, weakness in the legs is noticed first. In few others, the hands are weakened more rapidly than the legs. Weakness is progressive, which means the muscle becomes weaker over time. IBM2 does not seem to affect the brain, internal organs or sensation. The quadriceps are relatively spared, and remain strong until the late stages of disease, which is the reason IBM2 is often referred to as Quadriceps Sparing Myopathy (QSM).

Physical expression of nemaline myopathy varies greatly, but weakness is usually concentrated in the proximal muscles, particularly respiratory, bulbar and trunk muscles. People with severe NM show obvious symptoms at birth, while those with intermediate or mild NM may initially appear unaffected. Babies with NM are frequently observed to be "floppy" and hypotonic. Children born with NM often gain strength as they grow, though the effect of muscle weakness on body features may become more evident with time. Adults with NM typically have a very slender physique.

Signs and symptoms include (for each of the following causes):

- Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like syndrome (MELAS)

- Varying degrees of cognitive impairment and dementia

- Lactic acidosis

- Strokes

- Transient ischemic attacks

- Hearing loss

- Weight loss

- Myoclonic epilepsy and ragged-red fibers (MERRF)

- Progressive myoclonic epilepsy

- Clumps of diseased mitochondria accumulate in muscle fibers and appear as "ragged-red fibers" when muscle is stained with modified Gömöri trichrome stain

- Short stature

- Kearns-Sayre syndrome (KSS)

- External ophthalmoplegia

- Cardiac conduction defects

- Sensorineural hearing loss

- Chronic progressive external ophthalmoplegia (CPEO)

- Progressive ophthalmoparesis

- Symptomatic overlap with other mitochondrial myopathies

Bulbar (throat) muscle weakness is a main feature of nemaline myopathy. Most individuals with severe NM are unable to swallow and receive their nutrition through feeding tubes. Most people with intermediate and mild NM take some or all of their nutrition orally. Bulbar muscle impairment may also lead to difficulty with communication. People with NM often have hypernasal speech as a result of poor closure of the velopharyngeal port (between the soft palate and the back of the throat). Communicative skills may be enhanced through speech therapy, oral prosthetic devices, surgery, and augmentative communication devices. Individuals with NM are usually highly sociable and intelligent, with a great desire to communicate.

Many patients report that temperature may affect the severity of symptoms, especially cold as being an aggravating factor. However, there is some scientific debate on this subject, and some even report that cold may alleviate symptoms.

Acquired non-inflammatory myopathy (ANIM) is a neurological disorder primarily affecting skeletal muscle, most commonly in the limbs of humans, resulting in a weakness or dysfunction in the muscle. A myopathy refers to a problem or abnormality with the myofibrils, which compose muscle tissue. In general, non-inflammatory myopathies are a grouping of muscular diseases not induced by an autoimmune-mediated inflammatory pathway. These muscular diseases usually arise from a pathology within the muscle tissue itself rather than the nerves innervating that tissue. ANIM has a wide spectrum of causes which include drugs and toxins, nutritional imbalances, acquired metabolic dysfunctions such as an acquired defect in protein structure, and infections.

Acquired non-inflammatory myopathy is a different diagnosis than inflammatory myopathy. Inflammatory myopathies are a direct result of some type of autoimmune mediated pathway whereas ANIM is not the result of a dysfunction of the immune system. In addition, the cause of inflammatory myopathy is relatively unknown, whereas many causal agents for ANIM have been discovered which typically affect the structural integrity and function of the muscle fibers.

Most myopathies are typically first diagnosed and classified as an idiopathic inflammatory myopathy. However, a diagnosis of ANIM occurs when the cause of the myopathy is found to not arise from an autoimmune mechanism.

The prolonged muscle contractions, which occur most commonly in the leg muscles in recessive mutations, and more commonly in the hands, face, and eyelids in dominant mutations, are often enhanced by inactivity, and in some forms are relieved by repetitive movement known as "the warm-up effect". This effect often diminishes quickly with rest. Some individuals with myotonia congenita are prone to falling as a result of hasty movements or an inability to stabilize themselves after a loss of balance. During a fall, a person with myotonia congenita may experience partial or complete rigid paralysis that will quickly resolve once the event is over. However, a fall into cold water may render the person unable to move for the duration of submergence. As with myotonic goats, children are more prone to falling than adults, due to their impulsivity.

The two major types of myotonia congenita are distinguished by the severity of their symptoms and their patterns of inheritance. Becker disease usually appears later in childhood than Thomsen disease, and causes more severe myotonia, muscle stiffness and transient weakness. Although myotonia in itself is not normally associated with pain, cramps or myalgia may develop. People with Becker disease often experience temporary attacks of muscle weakness, particularly in the arms and hands, brought on by movement after periods of rest. They may also develop mild, permanent muscle weakness over time. This muscle weakness is not observed in people with Thomsen disease. However, in recent times, as more of the individual mutations that cause myotonia congenita are identified, these limited disease classifications are becoming less widely used.

Early symptoms in a child may include:

- Difficulty swallowing

- Gagging

- Stiff movements that improve when they are repeated

- Frequent falling

- Difficulties opening eyelids after strenuous contraction or crying (von Graefe's sign)

Possible complications may include:

- Aspiration pneumonia (caused by swallowing difficulties)

- Frequent choking or gagging in infants (also caused by swallowing difficulties)

- Abdominal muscle weakness

- Chronic joint problems

- Injury due to falls

Centronuclear myopathies (CNM) are a group of congenital myopathies where cell nuclei are abnormally located in skeletal muscle cells. In CNM the nuclei are located at a position in the center of the cell, instead of their normal location at the periphery.

Symptoms of CNM include severe hypotonia, hypoxia-requiring breathing assistance, and scaphocephaly. Among centronuclear myopathies, the X-linked myotubular myopathy form typically presents at birth, and is thus considered a congenital myopathy. However, some centronuclear myopathies may present later in life.

The onset of this disease can begin even before birth but is more commonly in childhood or later into adult life. The progression is slow, with symptoms of weakness and walking difficulties sometimes not presenting until middle age. Early symptoms include Gower's sign ("climbing" up the thighs with the hands when rising from the floor) and tiptoe-walking caused by the beginning of contractures.

Bethlem myopathy affects about 1 in 200,000 people. Contractures of the fingers are a typical symptom of Bethlem myopathy but not of the related Ullrich's myopathy (which does include contractures of arms and legs, as does Bethlem myopathy). Serum creatine kinase is elevated in Bethlem myopathy, as there is ongoing muscle cell death. Patients with Bethlem myopathy may expect a normal life span and continued mobility into adulthood. There is currently no cure for this disorder, but the contractures of the legs can be alleviated with heel-cord surgery followed by bracing and regular physical therapy. Repeated surgeries to lengthen the heel cords may be needed as the child grows to adulthood.

Mitochondrial myopathies are types of myopathies associated with mitochondrial disease. On biopsy, the muscle tissue of patients with these diseases usually demonstrate "ragged red" muscle fibers. These ragged-red fibers contain mild accumulations of glycogen and neutral lipids, and may show an increased reactivity for succinate dehydrogenase and a decreased reactivity for cytochrome c oxidase. Inheritance was believed to be maternal (non-Mendelian extranuclear). It is now known that certain nuclear DNA deletions can also cause mitochondrial myopathy such as the OPA1 gene deletion. There are several subcategories of mitochondrial myopathies.

As with other myopathies, the clinical manifestations of MTM/CNM are most notably muscle weakness and associated disabilities. Congenital forms often present with neonatal low muscle tone, severe weakness, delayed developmental milestones (particularly gross motor milestones such as head control, crawling, and walking) and pulmonary complications (presumably due to weakness of the muscles responsible for respiration). While some patients with centronuclear myopathies remain ambulatory throughout their adult life, others may never crawl or walk and may require wheelchair use for mobility. There is substantial variability in the degree of functional impairment among the various centronuclear myopathies. Although this condition only affects the voluntary muscles, several children have suffered from cardiac arrest, possibly due to the additional stress placed on the heart.

Other observed features have been high arched palate, long digits, bell shaped chest and long face.

Myotubular myopathy only affects muscles and does not impact intelligence in any shape or form.

X-linked myotubular myopathy was traditionally a fatal condition of infancy, with life expectancy of usually less than two years. There appears to be substantial variability in the clinical severity for different genetic abnormalities at that same MTM1 gene. Further, published cases show significant differences in clinical severity among relatives with the same genetic abnormality at the MTM1 gene. Most truncating mutations of MTM1 cause a severe and early lethal phenotype, while some missense mutations are associated with milder forms and prolonged survival (up to 54 years).

Centronuclear myopathies typically have a milder presentation and a better prognosis. Recently, researchers discovered mutations at the gene dynamin 2 (DNM2 on chromosome 19, at site 19p13.2), responsible for the autosomal dominant form of centronuclear myopathy. This condition is now known as dynamin 2 centronuclear myopathy (abbreviated DNM2-CNM). Research has indicated that patients with DNM2-CNM have a slowly progressive muscular weakness usually beginning in adolescence or early adulthood, with an age range of 12 to 74 years.

The symptoms of CCD are variable, but usually involve hypotonia (decreased muscle tone) at birth, mild delay in child development (highly variable between cases), weakness of the facial muscles, and skeletal malformations such as scoliosis and hip dislocation.

Symptoms may be present at birth or may appear at any stage of life. There appears to be a growing number of people who do not become symptomatic until adulthood to middle age. While generally not progressive, again there appears to be a growing number of people who do experience a slow clinically significant progression of symptomatology. These cases may hypothetically be due to the large number of gene mutations of ryanodine receptor malfunction, and with continued research may in fact be found to be clinical variants.

Presentation of symptoms and signs varies considerably by form (DM1/DM2), severity and even unusual DM2 phenotypes. DM1 symptoms for DM2 include problems with executive function (e.g., organization, concentration, word-finding) and hypersomnia. Conduction abnormalities are more common in DM1 than DM2, but all people are advised to have an annual ECG. Both types are also associated with insulin resistance. Myotonic dystrophy may have a cortical cataract with a blue dot appearance, or a posterior subcapsular cataract.

DM2 is generally milder than DM1, with generally fewer DM2 people requiring assistive devices than DM1 people. In addition, the severe congenital form that affects babies in DM1 has not been found in DM2 and the early onset of symptoms is rarely noted to appear in younger people in the medical literature.

Symptoms may appear at any time from infancy to adulthood. DM causes general weakness, usually beginning in the muscles of the hands, feet, neck, or face. It slowly progresses to involve other muscle groups, including the heart. DM affects a wide variety of other organ systems as well.

As a result of lower motor neurone degeneration, the symptoms of PMA include:

- atrophy

- fasciculations

- muscle weakness

Some patients have symptoms restricted only to the arms or legs (or in some cases just one of either). These cases are referred to as "Flail Arm" (FA) or "Flail Leg" (FL) and are associated with a better prognosis.

Common symptoms of the disease are weakness and atrophy in the distal muscles of the lower limbs which progresses to the hands and arms, then to the trunk, neck and face. Respiratory impairment often follows.

Myotonic dystrophy is a long term genetic disorder that affects muscle function. Symptoms include gradually worsening muscle loss and weakness. Muscles often contract and are unable to relax. Other symptoms may include cataracts, intellectual disability, and heart conduction problems. In men there may be early balding and an inability to have children.

Myotonic dystrophy is an autosomal-dominant disorder which is typically inherited from a person's parents. There are two main types: type 1 (DM1) due to mutations in the DMPK gene and type 2 (DM2) due to mutations in the CNBP gene. The disorder generally worsens in each generation. A type of DM1 may be apparent at birth. DM2 is generally milder. They are types of muscular dystrophy. Diagnosis is confirmed by genetic testing.

There is no cure. Treatments may include braces or wheelchairs, pacemakers, and non invasive positive pressure ventilation. The medications mexiletine or carbamazepine are occasionally helpful. Pain if it occurs may be treated with tricyclic antidepressants and nonsteroidal anti inflammatory drugs (NSAIDs).

Myotonic dystrophy affects more than 1 in 8,000 people worldwide. While myotonic dystrophy can occur at any age, onset is typically in the 20s and 30s. It is the most common form of muscular dystrophy that begins in adulthood. It was first described in 1909 with the underlying cause of type 1 determined in 1992.

How sIBM affects individuals is quite variable as is the age of onset (which generally varies from the forties upwards). Because sIBM affects different people in different ways and at different rates, there is no "textbook case."

Eventually, sIBM results in general, progressive muscle weakness. The muscles in the thighs called the quadriceps and the muscles in the arms that control finger flexion—making a fist—are usually affected early on. Common early symptoms include frequent tripping and falling, weakness going up stairs and trouble manipulating the fingers (including difficulty with tasks such as turning doorknobs or gripping keys). Foot drop in one or both feet has been a symptom of IBM and advanced stages of polymyositis (PM).

During the course of the illness, the patient's mobility is progressively restricted as it becomes hard for him or her to bend down, reach for things, walk quickly and so on. Many patients say they have balance problems and fall easily, as the muscles cannot compensate for an off-balanced posture. Because sIBM makes the leg muscles weak and unstable, patients are very vulnerable to serious injury from tripping or falling down. Although pain has not been traditionally part of the "textbook" description, many patients report severe muscle pain, especially in the thighs.

When present, difficulty swallowing (dysphagia) is a progressive condition in those with inclusion body myositis and often leads to death from aspiration pneumonia. Dysphagia is present in 40 to 85% of IBM cases.

IBM can also result in diminished capacity for aerobic exercise. This decline is most likely a consequence of the sedentary lifestyle that is often associated with the symptoms of IBM (i.e. progressive muscle weakness, decreased mobility, and increased level of fatigue). Therefore, one focus of treatment should be the improvement of aerobic capacity.

Patients with sIBM usually eventually need to resort to a cane or a walker and in most cases, a wheelchair eventually becomes a necessity.

"The progressive course of s-IBM leads slowly to severe disability. Finger functions can become very impaired, such as for manipulating pens, keys, buttons, and zippers, pulling handles, and firmly grasping handshakes. Arising from a chair becomes difficult. Walking becomes more precarious. Sudden falls, sometimes resulting in major injury to the skull or other bones, can occur, even from walking on minimally-irregular ground or from other minor imbalances outside or in the home, due to weakness of quadriceps and gluteus muscles depriving the patient of automatic posture maintenance. A foot-drop can increase the likelihood of tripping. Dysphagia can occur, usually caused by upper esophageal constriction that often can be symptomatically improved, for several months to years, by bougie dilation per a GI or ENT physician. Respiratory muscle weakness can sometimes eventuate."

In contrast to amyotrophic lateral sclerosis or primary lateral sclerosis, PMA is distinguished by the "absence" of:

- brisk reflexes

- spasticity

- Babinski's sign

- Emotional lability

In terms of the signs (and symptoms) of oculopharyngeal muscular dystrophy would be consistent with the following:

Though the aforementioned signs/symptoms are the most common, there have been cases though rare, where the peripheral nervous system has had involvement with significant reduction of myelinated fibers

In homozygous cases, this muscular dystrophy is severe and starts earlier in the affected individuals life.