Neurological Screen: Difference between revisions
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== Sensory Testing == | == Sensory Testing == | ||
Sensory testing is a commonly utilised method for assessing the functionality of the nervous system without invading the body. This approach relies on understanding the dermatomes and sensory regions of cutaneous nerves. Although a conclusive diagnosis cannot be reached exclusively through sensory testing, it remains an essential tool for pinpointing the origin of neural injuries. The peripheral nerves convey all skin sensations via their cutaneous branches as they extend into the trunk, while each spinal nerve supplies a specific area of skin, resulting in dermatomal patterns for each nerve. By examining these areas, healthcare professionals can gain insights into potential neural abnormalities. <ref name=":4">Downs MB, Laporte C. Conflicting dermatome maps: educational and clinical implications. journal of orthopaedic & sports physical therapy. 2011 Jun;41(6):427-34.</ref> | |||
=== Peripheral Nerves === | === Peripheral Nerves === | ||
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The term “[[Dermatomes|dermatome]]” is a combination of two Greek words; “derma” meaning “skin”, and “tome”, meaning “cutting” or “thin segment”. Dermatomes are areas of the skin whose sensory distribution is innervated by the afferent nerve fibres from the dorsal root of a specific nerve root. Assessment of dermatomes involves bilateral comparison of light touch discrimination. | The term “[[Dermatomes|dermatome]]” is a combination of two Greek words; “derma” meaning “skin”, and “tome”, meaning “cutting” or “thin segment”. Dermatomes are areas of the skin whose sensory distribution is innervated by the afferent nerve fibres from the dorsal root of a specific nerve root. Assessment of dermatomes involves bilateral comparison of light touch discrimination. | ||
The idea of dermatomes originated from initial efforts to associate anatomy with the physiology of sensation. Multiple definitions of dermatomes exist, and several maps are commonly employed. Although they are valuable, dermatomes vary significantly between maps and even among individuals,<ref name=":2">Apok V, Gurusinghe NT, Mitchell JD, Emsley HC. Dermatomes and dogma. Practical neurology. 2011 Apr 1;11(2):100-5.</ref> with some evidence suggesting that current dermatome maps are inaccurate and based on flawed studies.<ref name=":3">Lee MW, McPhee RW, Stringer MD. An evidence-based approach to human dermatomes. Australasian Musculoskeletal Medicine. 2013 Jun;18(1):14-22.</ref> The medical profession typically had recognised two primary maps of dermatomes. Firstly, the Keegan and Garret Map (Fig.1) from 1948, which illustrates dermatomes in alignment with the developmental progression of the limb segments. Secondly, the Foerster Map from 1933, which portrays the medial area of the upper limb as being innervated by T1-T3, depicting the pain distribution from angina or myocardial infarction. This latter map is the most frequently implemented and is included in the assessment of [[Spinal Cord Injury|spinal cord injury]] using the [[American Spinal Cord Injury Association (ASIA) Impairment Scale|ASIA Scale]]. In recent years there have been few attempts at verifying these original dermatome maps. Lee et al conducted an in-depth review that examined the discrepancies among dermatome maps. They put forth an “evidence-based” dermatome map that combined elements of previous maps (Fig.3). Though the application of the term “evidence-based” may be somewhat questionable, their proposed map represents a systematic attempt to synthesise the most credible evidence available.<ref name=":2" /><ref name=":3" /> | The idea of dermatomes originated from initial efforts to associate anatomy with the physiology of sensation. Multiple definitions of dermatomes exist, and several maps are commonly employed. Although they are valuable, dermatomes vary significantly between maps and even among individuals,<ref name=":2">Apok V, Gurusinghe NT, Mitchell JD, Emsley HC. Dermatomes and dogma. Practical neurology. 2011 Apr 1;11(2):100-5.</ref> with some evidence suggesting that current dermatome maps are inaccurate and based on flawed studies.<ref name=":3">Lee MW, McPhee RW, Stringer MD. An evidence-based approach to human dermatomes. Australasian Musculoskeletal Medicine. 2013 Jun;18(1):14-22.</ref> <ref name=":4" /> | ||
The medical profession typically had recognised two primary maps of dermatomes. Firstly, the Keegan and Garret Map (Fig.1) from 1948, which illustrates dermatomes in alignment with the developmental progression of the limb segments. Secondly, the Foerster Map from 1933, which portrays the medial area of the upper limb as being innervated by T1-T3, depicting the pain distribution from angina or myocardial infarction. This latter map is the most frequently implemented and is included in the assessment of [[Spinal Cord Injury|spinal cord injury]] using the [[American Spinal Cord Injury Association (ASIA) Impairment Scale|ASIA Scale]]. In recent years there have been few attempts at verifying these original dermatome maps. Lee et al conducted an in-depth review that examined the discrepancies among dermatome maps. They put forth an “evidence-based” dermatome map that combined elements of previous maps (Fig.3). Though the application of the term “evidence-based” may be somewhat questionable, their proposed map represents a systematic attempt to synthesise the most credible evidence available.<ref name=":2" /><ref name=":3" /> | |||
During dermatome testing the examiner should alter or remove the pressure applied to one side to determine whether the patient can distinguish changes in pressure. | During dermatome testing the examiner should alter or remove the pressure applied to one side to determine whether the patient can distinguish changes in pressure. | ||
Revision as of 00:41, 15 June 2023
Original Editors - Naomi O'Reilly
Top Contributors - Naomi O'Reilly and Jess Bell
Introduction[edit | edit source]
Many rehabilitation professionals worldwide now assume a first contact role, which means that they may be the first medical professional to assess a patient presenting with impairments in body function. Given this it is essential that rehabilitation professionals have the ability to recognise the key elements of the patient subjective history, and the objective physical examination, which may be indicative of any serious pathology or a potential risk of serious adverse events.[1] The neurological screening examination is a “quick scan" used to rule out symptoms, which may be referred from one part of the body to another and to assess the integrity of the nervous system.
The neurological screen has always been considered a key element of safe and appropriate practice, and is commonly used to determine a patients neurological function.[2] A basic neurologic screen can be performed rapidly with practice. The presence of an abnormal result usually warrants further investigation and onward referrals to specific specialties.[2]
Why[edit | edit source]
Clinicians utilise a neurologic screen as a differential diagnostic tool to rule in or out such things as neurological diseases or injuries to the nervous system, and helps clinicians to determine whether signs and symptoms are caused by tissues innervated by the central nervous system (brain and spinal cord) or peripheral nervous system.
The main purpose of a neurological screen is to localise where in the nervous system the problem to one of the following areas;
- Upper Motor Neurones, which originate in the cerebral cortex and travel down to the brain stem or spinal cord;
- Lower Motor Neurones, which begin in the spinal cord and go on to innervate muscles.
To refresh your knowledge of neuroanatomy read here and to review your understanding of motor neurones read here.
Indications[edit | edit source]
A neurological screen is most appropriate to do when red flags are present. In cases where a patient sustained a possible injury to their brain, spinal cord or peripheral nervous system or if you feel one is appropriate.You may want to perform one as well, if a patient presents with any of the following:
- Injury to the Head or Spine
- Headaches
- Blurry or Double Vision
- Loss of Smell
- Impaired Hearing
- Impaired Speech
- Dizziness
- Seizures
- Tremors
- Change in Balance
- Change in Coordination
- Changes in Sensation
- Radicular Signs
- Muscle Weakness
- Numbness or Tingling in the Arms and/or Legs.
- Changes in Bowel and Bladder Function
- Presents with Abnormal Patterns
- Altered Mental State such as confusion, memory loss, cognitive decline or reported changes in behaviour [3]
When performing the neurological screen, it is important to keep the purpose of the examination in mind, namely to localise the lesion to the nervous system.
Reflex Testing[edit | edit source]
A reflex is an involuntary and nearly instantaneous movement in response to a stimulus. The reflex is an automatic response to a stimulus that does not receive or need conscious thought as it occurs through a reflex arc. Reflex arcs act on an impulse before that impulse reaches the brain.[4]
Several types of reflexes, including deep tendon reflexes, superficial reflexes, and pathological reflexes, can be tested as part of a physical examination and these all reveal something about the status of the elements of the nervous system that contribute to their functioning.
Deep Tendon Reflexes[edit | edit source]
Deep tendon reflexes evaluate afferent nerves, synaptic connections within the spinal cord, motor nerves, and descending motor pathways. Lower motor neuron lesions (eg affecting the anterior horn cell, spinal root or peripheral nerve) depress reflexes, while upper motor neuron lesions increase the reflexes.
Testing for deep tendon reflexes is most commonly used during a neurological screen using a reflex hammer to assesses the integrity of the stretch reflex arc of a specific nerve root, which provides information on the integrity of the specific nerve root. The rehabilitation professional strikes over the tendon insertion to place a slight quick– stretch on the tendon, which will elicit a reflex response (for example a muscle jerk response). The most common deep tendon reflexes assessed in the upper and lower extremities include the biceps, brachioradialis, triceps, patellar and the achilles tendon.
| Segmental Innervation | Nerve Supply | Muscle |
|---|---|---|
| C5-6 | Musculocutaneous | Biceps Brachii |
| C5-6 | Radial | Brachioradialis |
| C7-8 | Radial | Triceps |
| L2-4 | Femoral | Patellar |
| S1-2 | Tibial | Achilles |
Grading of deep tendon reflexes uses a 5-point scale to characterise the stretch reflex response and compare it bilaterally to the uninjured limb.
| Grade | Description |
|---|---|
| 0 | Reflex Absent |
| 1 | Somewhat Diminished or Requires Reinforcement |
| 2 | Average |
| 3 | Brisker than Average |
| 4 | Very Brisk with Clonus |
You can read more about the reflex arc and reflex testing here
Sensory Testing[edit | edit source]
Sensory testing is a commonly utilised method for assessing the functionality of the nervous system without invading the body. This approach relies on understanding the dermatomes and sensory regions of cutaneous nerves. Although a conclusive diagnosis cannot be reached exclusively through sensory testing, it remains an essential tool for pinpointing the origin of neural injuries. The peripheral nerves convey all skin sensations via their cutaneous branches as they extend into the trunk, while each spinal nerve supplies a specific area of skin, resulting in dermatomal patterns for each nerve. By examining these areas, healthcare professionals can gain insights into potential neural abnormalities. [7]
Peripheral Nerves[edit | edit source]
Dermatomes[edit | edit source]
The term “dermatome” is a combination of two Greek words; “derma” meaning “skin”, and “tome”, meaning “cutting” or “thin segment”. Dermatomes are areas of the skin whose sensory distribution is innervated by the afferent nerve fibres from the dorsal root of a specific nerve root. Assessment of dermatomes involves bilateral comparison of light touch discrimination.
The idea of dermatomes originated from initial efforts to associate anatomy with the physiology of sensation. Multiple definitions of dermatomes exist, and several maps are commonly employed. Although they are valuable, dermatomes vary significantly between maps and even among individuals,[8] with some evidence suggesting that current dermatome maps are inaccurate and based on flawed studies.[9] [7]
The medical profession typically had recognised two primary maps of dermatomes. Firstly, the Keegan and Garret Map (Fig.1) from 1948, which illustrates dermatomes in alignment with the developmental progression of the limb segments. Secondly, the Foerster Map from 1933, which portrays the medial area of the upper limb as being innervated by T1-T3, depicting the pain distribution from angina or myocardial infarction. This latter map is the most frequently implemented and is included in the assessment of spinal cord injury using the ASIA Scale. In recent years there have been few attempts at verifying these original dermatome maps. Lee et al conducted an in-depth review that examined the discrepancies among dermatome maps. They put forth an “evidence-based” dermatome map that combined elements of previous maps (Fig.3). Though the application of the term “evidence-based” may be somewhat questionable, their proposed map represents a systematic attempt to synthesise the most credible evidence available.[8][9]
During dermatome testing the examiner should alter or remove the pressure applied to one side to determine whether the patient can distinguish changes in pressure.
You can read more about dermatomes here
Strength Testing[edit | edit source]
When performing the motor examination on a patient presenting with weakness, it is important to remember that weakness could be a result of a lesion at any point in the nervous system: cerebral hemispheres, brain stem, spinal cord, anterior horn cell, nerve root (myotome), peripheral nerve, neuromuscular junction, or muscle.
Myotomes[edit | edit source]
Myotomes represent a group of muscles that are innervated from a single specific nerve root. Essentially, myotomes are the motor equivalent to dermatomes. Myotomes may be assessed for various muscle groups of the upper and lower extremities. Myotome testing is performed through sustained isometric contraction of a specific muscle. Common muscles tested during myotome assessment are listed below.
| Nerve Root | Upper Limb Movement | Nerve Root | Lower Limb Movement |
|---|---|---|---|
| C2 | Neck Flexion [10] | L2 | Hip Flexion |
| C3 | Neck Extension [10] | L3 | Knee Extension |
| C4 | Neck Lateral Flexion [10] | L4 | Ankle Dorsiflexion |
| C5 | Shoulder Abduction | L5 | Big Toe Extension |
| C6 | Elbow Flexion | S1 | Ankle Plantarflexion |
| C7 | Elbow Extension | S2 | Knee Flexion [10] |
| C8 | Thumb Extension | S3-4 | Anal Wink [10] |
| T1 | Finger Abduction |
Summary[edit | edit source]
These are the main elements that should be considered when conducting a basic neurological screen. These tests reflect the function of various parts of the central and peripheral nervous system, and if assessed in a systematic and logical fashion can provide us with information on the integrity of the nervous system and an indication to what area of the nervous system is impaired.
The results of the neurological screen are taken together to anatomically identify the lesion, which may be diffuse (e.g., neuromuscular diseases) or highly specific (e.g., abnormal sensation in one dermatome due to compression or injury of a specific spinal nerve). When performing your assessment, please remember the following:
- Looking for side to side symmetry: one side of the body serves as a control for the other.
- Determining whether it involves the peripheral nervous system, central nervous system or both.
- Establishing the location of the impairment.
We do not necessarily have to conduct every one of these assessments. Consider your patient’s history, including mechanism of injury, signs and symptoms and clinical reasoning in deciding when and what to assess.
References [edit | edit source]
- ↑ Taylor A, Mourad F, Kerry R, Hutting N. A guide to cranial nerve testing for musculoskeletal clinicians. Journal of Manual & Manipulative Therapy. 2021 Nov 2;29(6):376-90.
- ↑ 2.0 2.1 Shahrokhi M, Asuncion RM. Neurologic exam. InStatPearls [Internet] 2022 Jan 20. StatPearls Publishing.
- ↑ Magee D. Orthopaedic Physical Assessment WB Saunders. pg. 2002;478:483-631.
- ↑ Wikipedia. Reflex. Available from: https://en.wikipedia.org/wiki/Reflex (last accessed 21.4.2019)
- ↑ Rodriguez-Beato FY, De Jesus O. Physiology, Deep Tendon Reflexes.
- ↑ Bickley, L. S., Szilagyi, P. G., Hoffman, R. M., & Soriano, R. P. (2021). Bate’s Guide to Physical Examination and History Taking (13th ed.). Wolters Kluwer Health: Philadelphia.
- ↑ 7.0 7.1 Downs MB, Laporte C. Conflicting dermatome maps: educational and clinical implications. journal of orthopaedic & sports physical therapy. 2011 Jun;41(6):427-34.
- ↑ 8.0 8.1 Apok V, Gurusinghe NT, Mitchell JD, Emsley HC. Dermatomes and dogma. Practical neurology. 2011 Apr 1;11(2):100-5.
- ↑ 9.0 9.1 Lee MW, McPhee RW, Stringer MD. An evidence-based approach to human dermatomes. Australasian Musculoskeletal Medicine. 2013 Jun;18(1):14-22.
- ↑ 10.0 10.1 10.2 10.3 10.4 Magee, David. J (2006). "3". Orthopaedic Physical Assessment (4th ed.). St. Louis: Elsevier. pp. 121–181
