Peripheral nerve anatomy, pathophysio etc.

1. By : Hazelyn Amparo R. Panabe
BSPT 4

3. Peripheral N.S : beyond the brain and the spinal
cord.
Composed of:
Cranial nerves
Spinal nerves
Connects the brain and the spinal cord with
sensory receptors, muscles and glands.

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

5. Most Peripheral nerves contains both Afferent
and Efferent neurons.
• Afferent Neurons: Sensory neurons
• Efferent Neurons: Motor Neurons.

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

7. Dermatomes

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

11. Peripheral Nerves

12. 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

14. 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.

15. Pathologic Reactions of Peripheral
Nerves
1. Segmental Demyelination
2. Wallerian Degeneration
3. Axonal Degeneration

16. 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.

17. 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.

18. 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.

20. Classification of Neuropathies

21. Classification of Neuropathies
2 Major Categories of Neuropathy
1. Demyelinating
2. Axonal

22. Demyelination
• Can be localized/focal ( Carpal Tunnel
Syndrome)
• Can be generalized ( Guillain Barre Syndrome)

23. 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.

24. 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.

25. Classification Schemes
• Seddon System:
• Sunderland System: expansion of Seddon’s
system.
- Both are in common use -

27. Etiologies of Neuropathy

28. Etiologies of Neuropathy
1. Hereditary disorders
2. Toxic disorders
3. Systemic diseases
4. Entrapment disorders
5. Secondary to infectious processes

29. Systemic Diseases

30. Idiopathic Neuropathies

31. Entrapment Syndromes

32. Infectious Causes

33. • 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.

34. Evaluation of Patient with
Neuropathy

35. 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.

36. History
Key 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?

37. 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.

38. Physical Examination
2. Motor examination
• Muscle strength should be graded by functional tests
of multiple muscles and muscle groups.
• Patterns of Atrophy

39. 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.

40. Electrodiagnostic examination in
neuropathy

41. 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

42. Nerve Conduction Studies

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

44. Common Complications of
Neuropathy

45. Common Complications of Neuropathy
1. Muscle weakness
2. sensory loss
3. neuropathic pain
4. autonomic problems

46. 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.

47. 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.

48. • 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.

49. 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.

50. Sensory Loss
• Prescription of custom-molded footwares.
• Rocker bottom soles also help redistribute
pressure to help prevent foot trauma and
ulcers.

51. 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.

52. • 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 to
Amputation.

53. 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.

54. Neuropathic Pain
• Common problem
Medications:
Gabapentine
Carbamezepine
: 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

55. Neuropathic Pain
Analgesics
- NSAIDS
- Acetaminophen (paracetamol)
Opioids : For severe pain
TENS

56. (“,) Thank you <3 <3