LEC.15. Neuropathy.ppt LEC.15. Neuropathy.ppt

LEC.15. Neuropathy.ppt

1. An Approach
to Peripheral
Neuropathy
DR.ABDUL RASHAD
IIRS

http://www.apsu.edu/thompsonj/Anatomy%20&%20Physiology/2010/2010%20Exam
%20Reviews/Exam%204%20Review/CH%2013%20Peripheral%20Nerve
%20Histology.htm

2. The 3 questions of clinical neurology…
#1. Where is the lesion?
#2. What is the etiology?
#3. What is the treatment?
www.ama-assn.org/ ama/pub/category/7172.html

3. The patterns of peripheral
neuropathy…
www.ama-assn.org/ ama/pub/category/7172.html
• Mononeuropathy?
• Polyneuropathy?
multiple nerves
contiguous
typically length dependent
(“stocking-glove”)
Polyneuropathy is common! 2.4%
(8% over 55 yr)

4. Overview of the Lecture –Mastering polyneuropathy
#1. Where is the injury?
The syndrome depends on:
•what modalities are injured,
•what fibers are injured,
•whether axon or myelin (or both) injured.
#2. What is the etiology?
Tricky – hence an approach necessary at the bedside.
#3. What is the treatment?
Depends on reversing the underlying cause.
Three common examples

5. http://www.neuro.wustl.edu/neuromuscular/pathol/nervenl.htmhttp://fulton.edzone.net/cites/winkler-science/team1/chap8.html

6. The clinical effect of a polyneuropathy depends on
1) what modalities involved
2) what fibers are effected
3) whether the injury is axonal or demyelinating.
Adapted from http://www.neuroanatomy.wisc.edu/SClinic/Weakness/Weakness.htm

7. Loss of function
“- symptoms”
Disturbed function
“+ symptoms”
Motor nerves Wasting
Hypotonia
Weakness
Hyporeflexia
Orthopedic deformity
Fasiculations
Cramps
The clinical response to motor nerve injury

8. www.neuro.wustl.edu/neuromuscular/pics/people/patients/Hands/handatrophymnd3.jpg

9. Loss of function
“- symptoms”
Disordered function
“+ symptoms”
Sensory
“Large Fiber”
↓ Vibration
↓ Proprioception
Hyporeflexia
Sensory ataxia
Paresthesias
Sensory
“Small Fiber”
↓ Pain
↓ Temperature
Dysesthesias
Allodynia
The clinical response to sensory nerve injury

10. Loss of function
“- symptoms”
Disturbed function
“+ symptoms”
Autonomic nerves↓ Sweating
Hypotension
Urinary retention
Impotence
Vascular color changes
↑ Sweating
Hypertension
The clinical response to autonomic nerve injury

11. http://www.neuro.wustl.edu/neuromuscular/nother/skel.html#nosteo

12. The two types of peripheral neuropathies:
axonopathies and myelinopathies

13. From Kumar: Robbins and Cotran: Pathologic Basis of Disease, 7th ed.

14. Copyright ©2002 BMJ Publishing Group Ltd.
Hughes, R. A C BMJ 2002;324:466-469
Using nerve conduction studies in polyneuropathy
http://www.neuroanatomy.wisc.edu/SClinic/Weakness/Weakness.htm
= Slow!
= Low!
= Slow!

15. http://missinglink.ucsf.edu/lm/ids_104_musclenerve_path/student_musclenerve/nervepath.html
Normal Nerve Axonal degeneration

16. Wallerian Degeneration
http://missinglink.ucsf.edu/lm/ids_104_musclenerve_path/student_musclenerve/nervepath.html

17. Axonopathies
•By far the majority of the toxic, metabolic and endocrine
causes
•Legs>> arms.
•EMG: Signs of denervation (acute, chronic) and
reinnervation

18. Segmental Demyelination
http://www.neuro.wustl.edu/neuromuscular/pathol
Normal
Demyelination
Normal
Demyelination

19. Myelinopathies
•Unusual by comparison with axonopathies
•Clues:hypertrophic nerves on exam
global arreflexia
weakness without wasting
motor >> sensory deficits
NCS can discriminate inherited from acquired
•NCS: Distal motor latency prolonged
Conduction velocities slowed
May have conduction block
EMG: Reduced recruitment w/o much denervation

20. Question #2. What is the etiology?
Only a limited number of ways a peripheral
nerve can react to injury, thus a multitude of
different etiologies can cause similar effects…

21. Problem: The multitude causes of peripheral
neuropathy!!!
Inherited: e.g. Charcot-Marie-Tooth disease (HMSN)
Infectious:e.g. Leprosy
Inflammatory: e.g. Guillain Barre syndrome (AIDP)
Neoplastic:e.g. Monoclonal gammopathy
Metabolic: e.g. Diabetes
Drug: e.g. Vincristine
Toxic: e.g. Ethanol

22. How then are we to sort through the causes to
make an etiologic diagnosis?...
Use the 6 D’s….
1.What is the distribution of the deficits?
2.What is the duration?
3.What are the deficits (which fibers are involved)?
4.What is the disease pathology (axonal or
demyelinating or mixed)
5.Is there an inherited (developmental) neuropathy?
6.Is there drug/toxin exposure?

23. 1. What is the distribution of the deficits?
•Asymmetry
1. Mononeuropathy
2. Mononeuritis multiplex – e.g.
vasculitis
•Symmetric (glove/stocking) = polyneuropathy

24. 2. What is the duration?
•Most polyneuropathies are chronic – ++months-yrs
•Acute polyneuropathies
e.g. Guillain Barre syndrome
Vasculitis
•Relapses and remissions
e.g. Intermittent toxin exposure
Ask: Acute or Chronic?

25. 3. What are the deficits (which fibers affected)?
•If predominant motor fibers think of:
Guillain Barre syndrome
Lead toxicity
Charcot-Marie-Tooth disease
•If pure sensory/ severe proprioceptive deficit, think of sensory
neuronopathy:
Carcinoma (paraneoplastic)
Vitamin B6 toxicity
•If autonomic nerves involved (small fiber) think of:
Diabetes
Amyloid
Drugs like vincristine, ddI, ddC

26. 4. What is the disease pathology?
•The vast majority are axonal.
•Demyelination a key finding because its causes are
relatively few.
•If demyelination uniform the cause is hereditary.
e.g. Charcot-Marie Tooth type I (HMSN)
•If otherwise unremarkable chronic sensorimotor
axonal polyneuropathy… exclude
alchohol, diabetes, hypothyroidism, uremia,
B12 deficiency & monoclonal gammopathy

27. 5. Is there an inherited (developmental) neuropathy?
• Among the most common!
• Clues – orthopedic deformities (feet, spine)
– long duration
– indolent progression
– few “positive” symptoms
– examine/question the family members!

28. 6. Drug or toxin exposure?
e.g.
Cancer drugs like vincristine
and paclitaxel
Antibiotics like chloroquine,
ethambutol, isoniazid and
metronidazole
Cardiac medications like
amiodarone
e.g.
Glue sniffing
Arsenic
Demyelinating Axonal

29. Polyneuropathy Example #1
•58 year old movie industry executive
•2 yrs toe numbness, paresthesias and pain
•Stocking numbness of toes with absent ankle jerks
•No medical history or family history or medications
•Multiple consultations & lab testing without etiologic
diagnosis

30. (A common axonal polyneuropathy)
Ethanol Neuropathy
•Among the most common neuropathies worldwide
•Chronic
•Numbness, paresthesias, pain in stocking distribution
•Sensory >>> Motor
•Loss of ankle reflexes
•History!
•Ethanol toxicity and nutritional deficiency
•Vitamin B1 (thiamine)

31. Polyneuropathy Example #2
•55 year old obese woman
•Family history positive for diabetes
•4-5 years of nocturia and 1-2 years of polyuria
•Dry skin over the feet
•Stocking numbness in all modalities to the ankles
•Absent ankle reflexes

32. (A common mixed axonal & demyelinating polyneuropathy)
Diabetic Polyneuropathy
•Multiple forms of neuropathy in diabetes
•Sensory >>> motor polyneuropathy
•Autonomic involvement common
•CSF protein frequently elevated
•Glucose control!
•Foot care

33. Peripheral Neuropathy in summary…
1. Patterns: mononeuropathy, mononeuropathy multiplex or
polyneuropathy – focal, multifocal or diffuse
2. “Signature” manifestations of a polyneuropathy depend
on what modalities affected (motor, sensory, autonomic)
and whether it is axonal or demyelinating.
3. Examination, NCS/EMG & biopsy can discriminate
axonopathy from myelinopathy
4. The multiple potential etiologies of polyneuropathy are
manageable recognizing patterns of disease

34. The Motor Unit
From Dumitru, D. Electrodiagnostic Medicine, Hanley & Belfus. Philadelphia. 1995