Cause
 | This section is empty. You can help by adding to it. (June 2024) |
| Hoffmann syndrome |
|---|
Hoffmann syndrome is a rare form of hypothyroid myopathy and is not to be confused with Werdnig-Hoffmann disease (a type of spinal muscular atrophy).
It was first documented in 1897 by Johann Hoffmann. [1] It has adult-onset symptoms and is comparable to the childhood-onset Kocher–Debré–Semelaigne syndrome. It is caused by low thyroid hormones (T3 and T4) with elevated TSH. [2] [3] [4] [5]
Signs and symptoms include exercise intolerance, muscle fatigue, muscle cramps, myalgia, delayed muscle relaxation (pseudomyotonia), proximal muscle weakness, delayed deep tendon reflexes (hyporeflexia) especially of the ankles, and a pseudoathletic appearance of hypertrophic calf muscles. There may also be bradycardia, mild anemia, dry skin, hoarse voice, and cold intolerance. EMG may be normal, neuropathic, myopathic, or mixed type. Serum CK may be normal or raised. The sign of myoedema (raised muscle tissue in response to percussive tactile stimulus) may be observed. Treatment is thyroid hormone replacement therapy and prognosis is generally good. Hypertrophic calves typically return to normal after approximately 3 months of treatment. [2] [3] [4] [5] [6]
| | This section is empty. You can help by adding to it. (June 2024) |
Muscle biopsy of hypothyroid myopathy shows atrophy of type II (fast-twitch/glycolytic) muscle fibres and a predominance of type I (slow-twitch/oxidative) muscle fibres; as well as abnormally high glycogen accumulation. [7] [8] [9] The reason for the muscle hypertrophy in Hoffmann syndrome is not clearly established; it may be due to altered carbohydrate metabolism, mucoid deposits, or glycosaminoglycan deposits. [3] [7] In an individual diagnosed with Hoffmann syndrome whose hypertrophy did not improve after thyroid hormone replacement therapy, muscle biopsy showed hypertrophy of muscle fibres with increased nuclei, few necrotic fibres and mucoid deposits in places. [6]
Diseases known to have a pseudoathletic appearance of the calves (hypertrophy or pseudohypertrophy), including exercise intolerance and/or muscle weakness:
Thyroid metabolism can be disrupted secondary to a primary disease. A common comorbidity of the metabolic myopathy McArdle disease (Glycogen storage disease type V) is hypothyroidism. [14] [15] It is also a comorbidity of late-onset Pompe disease (Glycogen storage disease type II). [16] [17] As both hyper- and hypothyroidism disrupts muscle glycogen metabolism, it is important to keep in mind differential diagnoses and their comorbidities when trying to determine whether signs and symptoms are either primary or secondary disease. [7] [8] [9] [18] [19]
| | This section is empty. You can help by adding to it. (June 2024) |
Kocher–Debré–Semelaigne syndrome(KDSS) is hypothyroidism in infancy or childhood characterised by lower extremity or generalized muscular hypertrophy (Herculean appearance), myxoedema, short stature, and cognitive impairment.
Glycogen storage disease type V, also known as McArdle's disease, is a metabolic disorder, one of the metabolic myopathies, more specifically a muscle glycogen storage disease, caused by a deficiency of myophosphorylase. Its incidence is reported as one in 100,000, roughly the same as glycogen storage disease type I.
A glycogen storage disease is a metabolic disorder caused by a deficiency of an enzyme or transport protein affecting glycogen synthesis, glycogen breakdown, or glucose breakdown, typically in muscles and/or liver cells.
Myotonia is a symptom of a small handful of certain neuromuscular disorders characterized by delayed relaxation of the skeletal muscles after voluntary contraction or electrical stimulation, and the muscle shows an abnormal EMG.
Glycogen storage disease type II(GSD-II), also called Pompe disease, and formerly known as GSD-IIa or Limb–girdle muscular dystrophy2V, is an autosomal recessive metabolic disorder which damages muscle and nerve cells throughout the body. It is caused by an accumulation of glycogen in the lysosome due to deficiency of the lysosomal acid alpha-glucosidase enzyme (GAA). The inability to breakdown glycogen within the lysosomes of cells leads to progressive muscle weakness throughout the body and affects various body tissues, particularly in the heart, skeletal muscles, liver and the nervous system.
In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. Myopathy means muscle disease. This meaning implies that the primary defect is within the muscle, as opposed to the nerves or elsewhere.
Exercise intolerance is a condition of inability or decreased ability to perform physical exercise at the normally expected level or duration for people of that age, size, sex, and muscle mass. It also includes experiences of unusually severe post-exercise pain, fatigue, nausea, vomiting or other negative effects. Exercise intolerance is not a disease or syndrome in and of itself, but can result from various disorders.
Sinus tachycardia is a sinus rhythm of the heart, with an increased rate of electrical discharge from the sinoatrial node, resulting in a tachycardia, a heart rate that is higher than the upper limit of normal.
Mitochondrial myopathies are types of myopathies associated with mitochondrial disease. Adenosine triphosphate (ATP), the chemical used to provide energy for the cell, cannot be produced sufficiently by oxidative phosphorylation when the mitochondrion is either damaged or missing necessary enzymes or transport proteins. With ATP production deficient in mitochondria, there is an over-reliance on anaerobic glycolysis which leads to lactic acidosis either at rest or exercise-induced.
In pathology, a contracture is a shortening of muscles, tendons, skin, and nearby soft tissues that causes the joints to shorten and become very stiff, preventing normal movement. A contracture is usually permanent, but less commonly can be temporary, or resolve over time but reoccur later in life.
Endocrine diseases are disorders of the endocrine system. The branch of medicine associated with endocrine disorders is known as endocrinology.
Myophosphorylase or glycogen phosphorylase, muscle associated (PYGM) is the muscle isoform of the enzyme glycogen phosphorylase and is encoded by the PYGM gene. This enzyme helps break down glycogen into glucose-1-phosphate, so it can be used within the muscle cell. Mutations in this gene are associated with McArdle disease, a glycogen storage disease of muscle.
Inborn errors of carbohydrate metabolism are inborn error of metabolism that affect the catabolism and anabolism of carbohydrates.
Muscle contractures can occur for many reasons, such as paralysis, muscular atrophy, and forms of muscular dystrophy. Fundamentally, the muscle and its tendons shorten, resulting in reduced flexibility.
Thyroid hormones are any hormones produced and released by the thyroid gland, namely triiodothyronine (T3) and thyroxine (T4). They are tyrosine-based hormones that are primarily responsible for regulation of metabolism. T3 and T4 are partially composed of iodine, derived from food. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as simple goitre.
Danon disease is a metabolic disorder. Danon disease is an X-linked lysosomal and glycogen storage disorder associated with hypertrophic cardiomyopathy, skeletal muscle weakness, and intellectual disability. It is inherited in an X-linked dominant pattern.
Metabolic myopathies are myopathies that result from defects in biochemical metabolism that primarily affect muscle. They are generally genetic defects that interfere with the ability to create energy, causing a low ATP reservoir within the muscle cell.
Neutral lipid storage disease is a congenital autosomal recessive disorder characterized by accumulation of triglycerides in the cytoplasm of leukocytes, muscle, liver, fibroblasts, and other tissues. It commonly occurs as one of two subtypes, cardiomyopathic neutral lipid storage disease (NLSD-M), or ichthyotic neutral lipid storage disease (NLSD-I) which is also known as Chanarin–Dorfman syndrome), which are characterized primarily by myopathy and ichthyosis, respectively. Normally, the ichthyosis that is present is typically non-bullous congenital ichthyosiform erythroderma which appears as white scaling.
Pseudoathletic appearance is a medical sign meaning to have the false appearance of a well-trained athlete due to pathologic causes instead of true athleticism. It is also referred to as a Herculean or bodybuilder-like appearance. It may be the result of muscle inflammation, muscle hyperplasia, muscle hypertrophy, muscle pseudohypertrophy, or symmetrical subcutaneous deposits of fat or other tissue.