Two of the most common procedures used in neuromusculoskeletal examination are testing the skin to assess a patient's ability to feel various sensations and testing muscle strength. In testing the skin, we are attempting to determine if an area of altered sensation or a pattern of pain is related to a dermatome, an area of skin innervated by a single spinal nerve root.
While strength is the focus in myotome testing, we must also be aware of pain related to myotomes. Muscle pathologies such as trigger points and strains produce localized and referred patterns of pain.
Patterns of pain associated with dermatomes and myotomes are useful clinical indicators. The patterns help us differentiate and isolate tissues when searching for sources of pain. Identifying the correct source of pain is vital for arriving at the correct diagnosis.
Unfortunately, examination often jumps from dermatomes and myotomes to other procedures without investigation of additional sources of pain and their patterns; sources such as sclerotomes, viscerotomes and angiotomes.
Sclerotome Pain
Pain from bony, ligamentous and fascial structures innervated by the same single spinal nerve root is referred to as sclerotome pain. It is the type of deep pain felt from a pathological bone disease such as multiple myeloma or a metastatic tumor. It is also the type of pain felt from sprain of a joint.
To help differentiate between the types of pain, it is helpful to understand that some types of pain are localized to a specific area, while other types of pain are more diffuse as a result of their referred pain patterns. For example, pain from dermatomes is localized to a specific area of skin. Pain from myotomes and sclerotomes is diffuse and can be felt distant to the site of pathology, in other structures innervated by the same spinal nerve root.
Viscerotome and Angiotome Pain
Defuse referred pain is also a characteristic of viscerotomes and angiotomes. Viscerotome pain is generated by internal organs innervated by the same single spinal nerve root. Two familiar examples of viscerotome pain and its referral are associated with the gallbladder and the heart.
Gallbladder disease can cause pain in the area of the gallbladder, but can also produce back, chest and right-shoulder pain. Heart disease can cause pain in the chest over the heart, but can also produce neck, jaw and arm pain. Pain from heart disease can also be attributed to angiotomes.
Angiotomes are made up of vascular structures / blood vessels innervated by a single spinal nerve root. Examples of angiotomes pain include ipsilateral head pain caused by pathology of the common carotid artery, and neck, arm and shoulder pain caused by pathology of the subclavian artery.
Angiotome pain related to the common carotid and subclavian arteries, primarily neck and head pain, is an important clinical factor in the "controversy" related to cervical manipulation and stroke. Differentiation of head and neck pain associated with vascular pathology in the cervical region and head, and neck pain associated with neuromusculoskeletal pathology in the cervical region and head, is necessary when these communal symptoms are present.
Multiple Types of Pain
It must be noted that a patient can be experiencing more than one type of pain. Pain patterns may be a composite of the categories of pain listed here. This explains why some patients describe areas of pain that are larger than the individual dermatome, myotome, sclerotome, viscerotome and angiotome patterns.
This is common in many injury cases. A patient with strain / sprain injuries can be experiencing myotome pain from the strain, sclerotome pain from the sprain and possibly dermatome pain from injured spinal nerve roots.
The easiest way to differentiate dermatome, myotome, sclerotome, viscerotome and angiotome patterns of pain is through the use of diagrams. Simply compare the patient's description of pain to charts depicting known patterns for each type of pain. Comparisons can also be made using body figures marked by patients on entry forms.
Showing the established charts to a patient and asking the patient to identify the pattern that best represents their pain is another possibility. A quick Internet search will help locate diagrams of pain patterns for each category of pain discussed in this article. Most diagrams are available in poster and single-page sizes.
General Resources
- Hoppenfeld S, Zeide MS. Orthopaedic Dictionary. Philadelphia: Lippincott, 1994.
- Jones HR. Netter's Neurology. Philadelphia: Saunders, 2005.
- Magee D. Orthopaedic Physical Assessment, 5th Edition. St. Louis: Saunders, 2008.
- NCMIC. Current Concepts, Spinal Manipulation and Cervical Arterial Incidents, Clive: NCMIC Chiropractic Solutions, 2006.
- Van der El A. Orthopaedic Manual Therapy Diagnosis: Spine and Temporomandibular Joints. Sudbury: Jones and Bartlett, 2010.
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