Treatments & Therapies

Muscle biopsy – treatment, effect and risks

Muskelbiopsie

In a muscle biopsy , doctors remove muscle tissue from the skeletal muscles to diagnose neuromuscular diseases, for example in the presence of myopathies . Another task of muscle biopsy is to examine the preserved tissue material. Closely related fields are neurology , neuropathology and pathology .

What is muscle biopsy?

Various disease processes can cause pain or muscle weakness . These abnormalities result in permanent connective tissue , nervous system , vascular, or musculoskeletal problems and disorders . In the field of sports medicine , muscle biopsies are carried out to gain insight into muscle metabolism during and after physical exertion.

Muscle biopsy is induced in the case of atypical or unusual symptoms or when symptoms are predominantly limited to the muscles close to the trunk (proximal) . Tissue removal is an important medical tool for the differential diagnosis of suspected ALS (degenerative disease of the motor nervous system). However, it is not necessary in every case. The findings regarding the changes in muscle tissue, especially in diseases of the second motor neuron, are based on the evaluation of frozen muscle sections, which are routinely stained and examined with certain reagents for the existence of special enzymes . In ALS, only slightly weakened muscles are used for thebiopsy selected.

Usually, the four-headed thigh muscle (musculus quadriceps), the anterior lower leg muscle (musculus tibialis anterior) or the upper arm flexor muscle (musculus biceps) is used for a biopsy. Muscles damaged by non-specific influences such as direct trauma, pinched nerves or a nerve root lesion are unsuitable. A muscle that is injured, has been the subject of an EMG within the past three weeks, or has recently been the site of frequent injections is unsuitable for biopsy.

Function, effect & goals

The goal of muscle biopsy is to ensure the initiation of appropriate treatment after diagnosis. It enables doctors to identify anomalies in the examined musculoskeletal system . A muscle biopsy is straightforward and is performed under local anesthesia . The doctor selects a clearly diseased muscle for this procedure, but one that is not yet completely fatty or atrophic.

The clinical aspect or the results of examinations ( sonography , nuclear spin tomography ) form the basis for the selection of the appropriate muscle. If the selection of the tissue cannot be finally clarified, an electromyography (EMG) or an MRI is used. In order to avoid erroneous findings, the biopsy is not performed in areas where EMG electrodes have been placed or intramuscular injections have been made because the muscle tissue is damaged. 

There are two types of biopsy: the open biopsy and the core biopsy. Open tissue harvesting is the standard procedure. The local anesthetic is not injected into the directly affected tissue, but into the adjacent onesskin textures .

A small incision is then made to expose the affected muscle. A tissue sample is taken from this and the wound is closed with sutures after bleeding has stopped. A core biopsy removes tissue using a biopsy needle that is inserted percutaneously (under the skin) into the muscle. This tissue sampling is less invasive than the open method, but only a very small sample can be obtained.

If there is a suspicion of connective tissue diseases of the vessels, areas of the surrounding skin, fascia and subcutaneous fatty tissue are removed in addition to the muscle. The biopsy obtained is processed further in a pathological institute. 

Preferably, a muscle bundle 2 to 3 centimeters long and 0.3 to 0.5 centimeters thick in the direction of the muscle fibers is attached in situ (on site) at two ends to a stick (sterile cotton swab) in order to obtain the orientation of the tissue fibers, am Chopsticks excised and fixed immediately.

A buffered six percent glutaraldehyde solution consisting of 20 to 30 millimeters with phosphate buffer is suitable as a means of fixation for the electron microscopic examination and the semi-thin section method. A similar preparation, fixed in a four percent formaldehyde solution and embedded in paraffin, is suitable for light microscopic examination. 

An approximately 1 x 0.5 x 0.5 cm muscle section is then excised for immunohistochemical, enzyme histochemical and molecular biological examination. This piece should not be fixed or tied to a stick, but must be immediately deep-frozen in liquid nitrogen or taken to the pathology department in a closed container with a damp cloth to avoid drying out.

The pathologists take over the processing and carry out the histological examination. Due to the limited shelf life, shipping is by courier. The glutaraldehyde and formalin fixed samples are sent separately from the frozen muscle section. The containers with the muscle sections placed in the fixation solution are attached to the outside of the styrofoam box using adhesive strips. If they are in close proximity to the dry ice, the solutions will freeze and serious artifacts will result.

Tissue removal is induced in the following diseases:

  • Inflammation of the muscles ( polymyositis , inclusion body myositis)
  • systemic inflammatory diseases (vasculitis, eosinophilic syndromes)
  • Kongenitale Myopathy (Nemalin-Myopathy, Central-Core-Myopathy)
  • Myopathies in metabolic disorders (lipid storage myopathies)
  • mitochondrial diseases (myoclonus epilepsy with “ragged red” fibers)
  • toxic myopathies (chloroquine, colchicine, statins)
  • Rhabdomyolysis, muscular dystrophy (muscle wasting)
  • unclear diseases of the muscles

Routine pathological examinations are:

  • Elastica van Gieson stain (EvG) (fibrosis of the endomysial connective tissue in myopathies)
  • Modified Gömöri trichrome stain (inclusion bodies in nemaline myopathy)
  • Hematoxylin-eosin stain (inflammatory infiltrates in myositis)
  • Oil red staining (lipid storage in the case of carnitine palmitoyl transferase deficiency symptoms)
  • Acid phosphatase reaction (increased macrophage activity in inflammatory myopathies)
  • ATPase reaction at different pH values ​​(different fiber types and their disturbed distribution in chronic neurogenic damage)
  • NADH reaction (representation of the oxidative, intermyofibrillar network and its disorders in multicore myopathy, central core myopathy)
  • PAS staining (excessive storage of glycogen in McArdle disease)

Risks, side effects & dangers

Rare complications are infections and wound healing disorders. Since skeletal muscle tissue reacts in a maximally irritable and artefact-prone manner, there is a risk of bruising or further injury to the tissue. Bruising, discomfort and light bleeding at the donor site are possible.

Before the procedure, the doctor informs the patient about the individual risks and asks about contraindications, for example allergies to the anesthetics used . Bleeding disorders, aspirin and anticoagulants (medicines used to thin the blood) are important contraindications, which may only allow an intervention if the medication is stopped. 

To ensure that the patient is physically fit for the procedure, the doctor will perform a physical exam in addition to taking the medical history. After the procedure, the patient can quickly resume his or her everyday life, there are only minor restrictions. He must keep the interface sterile and dry and must not put too much stress on the affected muscle tissue.

Typical & common muscle diseases

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.