There are few diagnostic tests that a Physiotherapist performs in routine. These tests provide insights to a diagnosis. Faradic galvanic test, Reaction of Degeneration test, F wave and H reflex are mentioned over here. This helps a student to peak into the fantastic tools that a good physio uses to get maximum benefits in developing diagnostic skills,.

1. DIAGNOSTIC TESTS IN
PHYSIOTHERAPY
-Dr.Aniruddha Barot (PT)
M.P.T. (Musculoskeletal), B.P.T., C.K.T.T.
Civil Hospital, Ahmedabad.

2. INTRODUCTION
◦ Few diagnostic tests that can be used in routine Physiotherapy clinics
are mentioned over here.
1. Faradic Galvanic tests
2. Reaction of Degeneration test
3. H reflex
4. F wave

3. FARADIC – GALVANIC
TEST

4. INTRODUCTION
◦ This test uses the IG and faradic current for diagnosis of a nerve
injury or a tendon cut.

5. PARAMETERS
◦ Faradic current:
Pulse duration: 0.1-1 ms
Pulse frequency: 50-100 Hz.
Surge duration on and off so as to
produce a tetanic contraction of
innervated muscle.
Intensity: to produce a minimal
contraction.
◦ IG current:
Pulse duration: 100 ms or longer
Pulse frequency: 1 Hz or to get 1
twitch contraction per second.
Intensity: to produce a minimal
contraction.

6. TECHNIQUE
◦ The nerve is stimulated using first a LPDC (long pulse duration current –IG)
and then SPDC (short pulse duration current) and the response to both are
seen.
◦ Find the motor point of a muscle using the IG current and check the response.
◦ Keeping the motor point the same check the response to the SF current.

7. INTERPRETATION
◦ Response to IG current can be:
Brisk contraction: innervated
muscle or a neuropraxia injury
Sluggish contraction: denervated
muscle.
No contraction: Fibrosis of muscle.
◦ Response to SF current can be:
Brisk contraction: innervated
muscle or a neuropraxia injury
No contraction: Fibrosis of muscle.
• The principle is that a dennervated muscle
loses its property to respond to an SPDC.
• If a muscle contraction is seen and a related
joint movement is seen, it implies tendon
continuity.

8. ADVANTAGE
◦ Simple
◦ Easy
◦ Cheap
◦ Quick
◦ Gives an idea whether nerve degeneration is present or not especially in early
stages.

9. DISADVANTAGES
◦ Does not give the exact site of nerve injury.
◦ Does not describe the severity of injury.
◦ Does not show a change with regeneration.

10. REACTION OF
DEGENERATION TEST

11. INTRODUCTION
◦ This is similar to the F and G test except for the fact that only SF current is
used and response is checked.
◦ Used to assess the level of innervation of skeletal muscle.
◦ Provide information on integrity of alpha motor neurons innervating skeletal
muscle.

12. PARAMETERS
◦ Monophasic or biphasic- SF Current.
◦ Pulse duration: 0.1 ms
◦ Frequency: 20-50 Hz

13. TECHNIQUE
◦ A muscle is stimulated along the course of a nerve using an SPDC and the
response is observed.
◦ One begins with a proximal muscle and proceeds distally till response to
electrical stimulation stops.

14. INTERPRETATION
◦ Normal muscle: smooth tetanic contraction.
◦ Denervated muscle: no muscle contraction which suggests “reaction of
degeneration” loss of innervation to muscle.
◦ Partial denervation: some fibers are lost elicits contraction but
force is decreased “PRD”.
• This is a quick way to find the level of injury as a response to SPDC
below that is lost.

15. H REFLEX

16. INTRODUCTION
◦ H reflex or the Hoffman reflex is a late response.
◦ Late responses are responses or potentials that appear after the motor response
or the M wave due to the stimulation of a mixed nerve.
◦ “H reflex is a monosynaptic reflex elicited by submaximal stimulation of tibial
nerve and recorded from the calf muscle.”
◦ In normal adults, it can also be recorded in other muscles of the limbs; but not
from the small muscles of hands and feet except in children <2 years of age.

17. ◦ The H reflex allows the evaluation of the proximal segments of the
nerve, i.e., the roots and plexuses.
◦ Compared to F wave and SSEPs, they are better as F waves only
analyze the motor fibers of the nerve and SSEPs only evaluate the
sensory fibers.
◦ Reflex arc of H reflex consists of:
1. Fast conducting group Ia fibers act as afferents.
2. Spinal cord : site for synapsing of afferent fibers with alpha motor
neurons
3. Efferent fibers: supplying the muscles.

19. ◦ H reflex is facilitated by submaximal
stimulation and inhibited by stronger
stimulation.
◦ The inhibition of H reflex on stronger
stimulation, is attributed to collision of
orthodromic impulses by antidromic
conduction in motor axons.
◦ This occurs in efferent pathway, because of
faster conduction in afferent (1a) fibers.
◦ Besides collision of impulses, there are
number of other inhibitory mechanisms:
1. Renshaw cell inhibition
2. Supra-spinal inhibition
3. Inhibition by adjacent motor neurons

20. Inhibition of
H reflex

21. M
Wave
H
Reflex

22. TECHNIQUE
Position:
Patient should be semi-reclining or lie in a
prone position with leg & thigh firmly
supported.
The feet should hang freely with dorsum of
foot at right angle to tibia.
Recording:
The active surface electrode is placed at the
distal edge of calf muscle & reference
electrode on tendoachiles.

23. Stimulation:
A square wave pulse of 1 ms duration is used for preferential stimulation of large sensory
fibers.
Stimuli below 0.1 ms duration may activate motor fibers rather than sensory.
Cathod is kept proximal to anode to avoid anodal block.
Stimulus frequency should not exceed 1 in 5 seconds to exclude any effect of prior
stimulus.
The stimuli are adjusted so, as to evoke maximum H response amplitude.
At this strength, a small M wave may also be present.
Attention to M response may help in monitoring the strength of the stimulus.
At least 5 H responses should be studied for analysis.
By increasing the strength of stimulus to supra-maximal, maximum M response can be
recorded.
 3 M responses are measured for analysis.

25. Measurements:
The latency of H reflex is measured from the stimulus artifact to the first
deflection from the baseline.
The amplitude is measured from base-to-peak of negative phase or from peak-to-
peak.
H reflex in the upper limb can be recorded from Flexor carpi radialis(FCR).
 Surface electrode (recording) is placed on the
belly of FCR [at junction of upper 1/3rd &
lower 2/3rd of line between medial epicondyle
& radial styloid].
 And Median nerve is stimulated at cubital
fossa.

26. NORMAL VALUES
Soleus H reflex
Latency: 35 ms
FCR H reflex
Latency: 21 ms
H Reflex Amplitude
: 9.8±6.1 mV
M wave Amplitude :
24.6±6.6 mV
Rt. To Lt. asymmetry
of latency:
Soleus H reflex: 2 ms
&
FCR : 1.5 ms

27. ◦ HM Ratio:
It is the ratio of peak to peak amplitude of maximum H reflex to
the peak to peak amplitude of the maximum M wave.
It provides a measure of motor neuron pool activation during H
response.
Normal value of HM
Ratio: 0.4±0.2

28. CLINICAL IMPLICATIONS
◦ Evaluates proximal motor and sensory pathways.
◦ Helps in evaluating plexopathies and radiculopathies.
◦ GBS: H reflex may be absent/disappeared/delayed.
◦ S1 Radiculopathy: Soleus H reflex may be absent.
◦ C6-C7 Radiculopathy: Flexor carpi radialis H reflex may be abnormal.
◦ Identifies nerve root involvement before any EMG changes.
◦ Slowed latency: abnormal dorsal root function due to disc herniation or
impingement.

29. F WAVE

30. INTRODUCTION
◦ F waves are forms of NCS used to evaluate the proximal segment of a nerve
that is inaccessible for routine NCS.
◦ “An action potential evoked intermittently from a muscle by a supramaximal
electric stimulus to the nerve due to antidromic activation of motor neurons is
known as F wave”.
◦ They were first recorded from the foot muscles by Magladery and McDougal
in 1950, hence named “F wave”.
◦ They are late responses that result from antidromic activation of the motor
neurons.
◦ They involves the spinal cord as conduction occurs through the spinal cord at
the interface between peripheral nervous system and central nervous system.

32. CHARACTERISTICS OF F WAVE
◦ Smaller compared to the M wave.
◦ Has a variable configuration.
◦ Latency longer than M wave.
◦ Latency in Upper limb: approx. 30 seconds.
◦ Latency in Lower limb: approx. 60 seconds.
◦ The F wave is an inconsistent response hence, needs at least 10 consecutive
trials for calculation.
◦ Easy to elicit using supramaximal stimulus, unlike H reflex.

34. USES OF F WAVE
◦ Evaluate the proximal segment of a nerve.
◦ Compare the conduction in the proximal and distal segment of a nerve.
◦ Determine the site of conduction slowing; e.g. to differentiate a root lesion
from a distal neuropathy.
◦ Most useful in conditions involving the most proximal segment of a nerve:
 Thoracic outlet syndrome
 Gullain- Barre syndrome
 Radiculopathies with multiple root involvement
 Brachial plexus injuries etc.

35. PHYSIOLOGY
◦ The alpha motor
neuron forms both
the afferent and the
efferent pathway
for F wave.

37. ◦ Since there is no synapse involve, the F wave is not a reflex but
only a measure of motor conduction.
◦ Also there is reactivation of only a few AHC axon hillocks and
orthodromic action potentials are generated only in a few motor
axons, the amplitude of F wave is much smaller than the M wave.
PHYSIOLOGY

38. TECHNIQUE
◦ Stimulation:
Recording from any distal muscle by stimulating the appropriate nerve.
Intensity: Supramaximal (20-25% higher than that required to generate M
wave)
Rate of stimulation: less than equal to 5 Hz.
Cathode is placed proximal to anode to prevent anodal block.

39. ◦ Recording:
Recording electrode: on muscle belly-tendon montage
Amplitude gain: 200-500 µV/division.
Sweep speed: 5-10 ms/division.
Filter settings: 30-10 kHz.
Muscle needs to be completely relaxed, as a contracted state can enhance F
waves or produce an H reflex.
TECHNIQUE

41. LIMITATIONS
◦ Utility of F waves for diagnosis of radiculopathy is limited since only median,
ulnar and tibial nerves are routinely evaluated which allow evaluation of C8,
T1 and L5, S1 roots only.

42. References
U.K.Misra, Clinical neurophysiology, 3rd edition, Elsevier
publication.
N J Vyas. Principles & Practice of Physical Rehabilitation. 1st
edition. Jaypee publications.

43. THANK YOU