TBPI EMG Results

Following are the transcribed findings of my Electromyograohy EMG test (an electro-physiological examination used to determine the extent of nerve function loss) conducted at King Chulalongkorn Memorial Hospital, followed by my interpretations.

  • Low SNAP Amplitude of left Median, Ulnar nerves when compared to right side.

  • No response of left musculocutaneous and Radial Nerves

  • Increased Insertional Activity: Positive Square Wave (PSW), Fibrillation (FIB) without Motor Unit Action Potential (MUAP) are found in muscles:

    • deltoid,
    • Biceps,
    • Triceps,
    • Extensor Carpi Radialis,
    • Flexor Carpi Ulnaris,
    • Palmaris Longus,
    • Infraspinatus

  • Increase insertional activity: PSW, FIB with discrete MUAP are found in

    • left Extensor Indicis proprius
    • first dorsal interossei muscle

· Increase insertional activity: PSW, FIB found in left Serratus but MUAP cannot be tested due to severe pain

· No spontaneous discharge is found in left cervical paraspinal muscles.


The electrophysiological findings show post ganglionic left brachial plexus degeneration involving C5 to T1 root of plexus, to a very severe degree at C5,6, and C7

How I interpret is that I have severe legions at/around the roots of C5, C6, and C7, though C8 and T1 still seem to be spared coinciding with my wrist extension and hand gripping capability.

The presence of IIA, PSW, and FIB waves in the needling of upper extremities and forearm muscles at a levels of 3+ suggests denervation in the listed muscles.

I didn’t include the sensory left/right side comparison chart which shows that left (injured) Median (digit III) and Ulnar nerves (digit V) at the wrist response to be approximately 30 to 40 % of (weaker?) the right median, and 45 to 70 % of the right Ulnar.

There was no response detected for left radial nerve and musculotaneous nerves.

While the finding of degeneration (legion) at plexus roots is considered very severe, it’s not technically as bad as complete root avulsion–with no abnormal-spontaneous response at the cervical paraspinal muscles, it is concluded to be nerve ruptures as also suggested by the term postganglionic (as opposed to preganglionic which would have been the worst news)

…Suggesting that some kind of surgical intervention may likely be possible/useful–either at the nerve roots themselves and/or nerve-muscle transfers at the prime denervated muscles lacking MUAP i.e.biceps. I have yet to consult with the actual neuro and orthapedic surgeons to confirm the possibilities, and will update in due time.


TBPI EMG Results — 3 Comments

  1. Fellow TBPI journeyman. I am impressed with you thoughtfulness and movement forward. I wish you the best of recoveries and treasured new journeys.

  2. Pingback: Second Opinions for TBPI diagnosis prognosis | The Siamerican

  3. Pingback: Brachial plexus nerve exploration-repair: Microsurgery at Thai government hospital | The Siamerican

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