Peripheral Nerve Injury(Peripheral Neuropathy)

By : Hazelyn Amparo R. PanabeBSPT 4

Nerve Anatomy and Physiology

Peripheral Nervous System

Peripheral N.S : beyond the brain and the spinal cord.

Composed of:Cranial nerves Spinal nervesConnects the brain and the spinal cord with sensory receptors, muscles and glands.

• In the Cervical and Lumbosacral region, Axons intermingle with each other to form the Plexuses.

Most Peripheral nerves contains both Afferent and Efferent neurons.

• Afferent Neurons: Sensory neurons• Efferent Neurons: Motor Neurons.

Spinal Nerves

• Each spinal nerves innervates a characteristic sensory area (Dermatomes) and group of muscles (Myotomes)

Dermatomes

• Individual peripheral nerves also have their own distinctive sensory and motor territories.

Peripheral Nerves

Peripheral Nerves

• Each peripheral nerve is surrounded by an outer connective tissue sheath called the epineurium. Inside the epineurium, the axons are arranged in fascicles, which are surrounded by a perineurium.

Axons can intermingle and cross from one fascicle to another along the course of the nerve. Each individual nerve fiber is surrounded by a membrane called the endoneurium

Schwann Cell: enclose axons.• Myelinated fibers are wrapped by multiple layers

of Schwann cell membrane and are thereby more effectively insulated.

Nodes of Ranvier: are longitudinal gaps located between individual Schwann cells.• Saltatory conduction: allows for faster impulse

transmission with minimal expenditure of energy.

Pathologic Reactions of Peripheral Nerves

1. Segmental Demyelination2. Wallerian Degeneration3. Axonal Degeneration

Segmental Demyelination• Focal degeneration of the myelin sheath with sparing of the

axon

• disappearance of the sheath over segments of variable length, bounded on each end by one side of a node of Ranvier and an adjacent preserved segment of myelin.

• Myelin may also degenerate from axonal disease in a general process that may occur either proximal or distal to the site of axonal interruption.

Wallerian Degeneration

• a reaction of both the axon and myelin distal to the site of disruption of an axon.

• Aka “dying forward”, the nerve degenerates from the point of axonal damage outward.

Axonal Degeneration

• when the axon degenerates as part of a "dying-back" phenomenon.

• the axon is affected progressively from the distal-most site to the proximal.

• One possible explanation for this process is that the primary damage is to the neuronal cell body, which fails in its function of synthesizing proteins and delivering them to the distal parts of the axon.

Classification of Neuropathies

Classification of Neuropathies

2 Major Categories of Neuropathy1. Demyelinating2. Axonal

Demyelination

• Can be localized/focal ( Carpal Tunnel Syndrome)

• Can be generalized ( Guillain Barre Syndrome)

Axonal lesions

• Can also be focal or generalized.

• These can be traumatic in origin, arising secondary to compression, traction, or transaction.

• Generalized polyneuropathies may be caused by toxic or metabolic derangements.

Classification of Neuropathies

• Peripheral neuropathies can also have a mixture of demyelinating and axonal pathology. (mixed neuropathy)

• Localized nerve injuries can be further classified by the amount of myelin versus axonal involvement and the degree of severity.

Classification Schemes

• Seddon System:

• Sunderland System: expansion of Seddon’s system.

- Both are in common use -

Etiologies of Neuropathy

Etiologies of Neuropathy

1. Hereditary disorders2. Toxic disorders3. Systemic diseases4. Entrapment disorders5. Secondary to infectious processes

Systemic Diseases

Idiopathic Neuropathies

Entrapment Syndromes

Infectious Causes

• Leprosy: predominant cause of neuropathy.

• Diabetes and Alcoholism: the most common causes of diffuse peripheral neuropathies seen in the developed world.

• A specific cause for peripheral neuropathy cannot be identified in up to 1/3 of the cases.

Evaluation of Patient with Neuropathy

History• The diagnostic process begins with the physician

obtaining a careful history.

• The family, social, and occupational histories are important for identifying familial occurrences or toxic exposures.

HistoryKey Questions:• Is the onset sudden or gradual?• Is the progression rapid or slow?• Is the predominant manifestation sensory, motor, or both?• Is the distribution focal or generalized, distal or proximal,symmetric or asymmetric?• Is there autonomic involvement?• Does the patient have any associated diseases?

Physical Examination

1. Sensory Examination light touch, pinprick, proprioception, vibration, and

cold temperature should be tested. Document the extent and pattern of Sensory loss. helps track the progress of the disease. important for identifying patients who need to be

counseled about protecting hypoesthetic skin.

Physical Examination

2. Motor examination• Muscle strength should be graded by functional tests

of multiple muscles and muscle groups.• Patterns of Atrophy

Physical Examination

3. Reflex Testing muscle stretch reflexes (MSRs) are often decreased or

absent distally.

In some of the polyneuropathies, MSRs can be absent throughout.

Abnormally brisk reflexes suggest that a central nervous system process is present, rather than a peripheral nerve problem.

Electrodiagnostic examination in neuropathy

Nerve Conduction Studies

• most helpful part of the electrodiagnostic examination for the evaluation of peripheral nerve disorders.

• determine the conduction velocity of the nerve as well as the amplitude of the resulting action potential

Nerve Conduction Studies

Electromyography

• The electromyography (EMG) needle records the summated activity of the muscle fibers.

Common Complications of Neuropathy

Common Complications of Neuropathy

1. Muscle weakness2. sensory loss3. neuropathic pain4. autonomic problems

Muscle Weakness

• may result to joint contractures and muscle shortening.

• can be prevented with daily range of motion and muscle-stretching exercises

• Depending on the degree of weakness, this exercise can be passive, active-assistive, or active.

Muscle Weakness

• A program of gentle strengthening, which can include isometric, isotonic, isokinetic, manualresistive, and progressive-resistive exercise, should be carefully tailored to the patient.

• Paradoxical weakening ( overwork weakness) : Common to px. with strength levels of 3/5 or less.

• Px. needs close monitoring to make certain that the exercise is making them stronger rather than weaker.

• Proper Passive Positioning : when the patient's ability to change position voluntarily is impaired.

• Splinting: help prevent contractures in patients with prolonged, severe muscle weakness.

• Orthoses: increase function and aid in positioning.

Sensory Loss

• Feet are most commonly and most severely affected by loss of sensation in peripheral neuropathy.

• Repetitive joint trauma can lead to the development of neuroarthropathic (Charcot) joints.

Sensory Loss

• Prescription of custom-molded footwares.

• Rocker bottom soles also help redistribute pressure to help prevent foot trauma and ulcers.

Sensory Loss

• Daily skin examination: instruct Px. to do thorough, gentle cleaning and soaking techniques.

• Patients with peripheral neuropathy frequently have autonomic neuropathy as well, putting them at risk for dry and scaly skin over the distal legs and feet due to a lack of normal sweating.

• Apply moisturizing creams in the entire foot surface except between the toes.

• Patients should test the temperature of bath water with a thermometer to prevent scalding.

• The toenails should be cut square to help prevent ingrown toenails.

Improper care may lead toAmputation.

Autonomic dysfunction

• Most commonly associated with diabetes mellitus and GBS.

• The autonomic dysfunction in GBS can be life-threatening. These patients should have cardiac monitoring with close observation for dysrhythmias and blood pressure instability during the early stages of their disease.

Neuropathic Pain

• Common problem

Medications:GabapentineCarbamezepine: for prickling and tingling sensation / burning discomfort.: If these medications are going to work, some relief is typically noted by the patient in a day or two

Neuropathic Pain

Analgesics- NSAIDS- Acetaminophen (paracetamol)

Opioids : For severe pain

TENS

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