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AANEM Connect | Assistance with diagnosis of left upper limb weakness after surgery. View modes: 
David Speach - 2/26/2019 3:47:30 PM
Assistance with diagnosis of left upper limb weakness after surgery.
Nerve Conduction Studies
Anti Sensory Summary Table
 Stim Site NR Onset (ms) Peak (ms) Norm Peak (ms) P-T Amp (µV) Norm P-T Amp Site1 Site2 Delta-0 (ms) Dist (cm) Vel (m/s) Norm Vel (m/s)
Left Lat Ante Brach Cutan Anti Sensory (Lat Forearm)
Lat Biceps   1.3 1.9 <2.5 10.3 >6.0 Lat Biceps Lat Forearm 1.3 10.0 77  
Right Lat Ante Brach Cutan Anti Sensory (Lat Forearm)
Lat Biceps   1.4 1.9 <2.5 41.9 >6.0 Lat Biceps Lat Forearm 1.4 10.0 71  
Left Med Ante Brach Cutan Anti Sensory (Med Forearm)
Elbow   1.3 1.8 <2.6 4.7 >3.0 Elbow Med Forearm 1.3 10.0 77  
Site 2   1.7 2.2   3.7              
Right Med Ante Brach Cutan Anti Sensory (Med Forearm)
Elbow   1.8 2.2 <2.6 16.3 >3.0 Elbow Med Forearm 1.8 10.0 56  
Left Median Anti Sensory (2nd Digit)
Wrist   2.1 2.8 4.0 58.2 19 Palm 2nd Digit 1.0 7.0 70  
Palm   1.0 1.5 2.3 54.5   Wrist Palm 1.1 7.0 64  
Right Median Anti Sensory (2nd Digit)
Wrist   2.0 2.6 4.0 135.0 19            
Left Radial Anti Sensory (Base 1st Digit)
Wrist   1.8 2.2 <2.8 47.1 >11 Wrist Base 1st Digit 1.8 10.0 56  
Left Ulnar Anti Sensory (5th Digit)
Wrist   2.2 2.7 <4.0 41.9 >13 Wrist 5th Digit 2.2 14.0 64  
Motor Summary Table
 Stim Site NR Onset (ms) Norm Onset (ms) O-P Amp (mV) Norm O-P Amp Neg Area (mVms) Site1 Site2 Delta-0 (ms) Dist (cm) Vel (m/s) Norm Vel (m/s)
Left Median Motor (Abd Poll Brev)
Wrist   3.0 4.5 4.6 5.0 15.46 Elbow Wrist 3.3 18.0 55 >49
Elbow   6.3   4.8   16.99            
Right Median Motor (Abd Poll Brev)
Wrist   2.3 4.5 10.5 5.0 31.14            
Left Ulnar Motor (Abd Dig Minimi)
Wrist   2.6 3.7 8.1 7.9 21.79 B Elbow Wrist 2.4 18.4 77 >52
B Elbow   5.0   6.9   17.27            
Comparison Summary Table
 Stim Site NR Onset (ms) Peak (ms) Norm Peak (ms) P-T Amp (µV) Site1 Site2 Delta-P (ms) Norm Delta (ms)
Left Median/Radial Dig I Comparison (Digit 1 - 10cm)
Median   1.6 1.9   46.4 Median Digit 1 - 10cm 1.9 <0.5
Radial   1.4 1.8   4.7 Radial Digit 1 - 10cm 1.8  
F Wave Studies
 NR F-Lat (ms) Lat Norm (ms) L-R F-Lat (ms) L-R Lat Norm M-Lat (ms) FLat-MLat (ms)
Left Median (Mrkrs) (Abd Poll Brev)
NR   <33   <2.2    
Right Median (Mrkrs) (Abd Poll Brev)
  21.27 <33   <2.2 2.34 18.93
Left Ulnar (Mrkrs) (Abd Dig Min)
  26.23 <36   <2.5 1.93 24.30

 Side Muscle Nerve Root Ins Act Fibs HF Fascic Amp Dur Poly Recrt Config Comment
Left Deltoid Axillary C5-6 Incr 2+ None None Nml Nml Nml Reduced Nml  
Left Biceps Musculocut C5-6 Incr 4+ None None Absent Absent Absent Absent NA  
Left Triceps Radial C6-7-8 Incr 3+ None None Absent Absent Absent Absent NA mepps present
Left PronatorTeres Median C6-7 Incr 4+ None None Absent Absent Absent Absent NA  
Left 1stDorInt Ulnar C8-T1 Incr 4+ None None Nml Nml Absent Reduced Nml single mup
Left Opp Pollicis Median C8-T1 Incr 4+ None None Absent Absent Absent Absent Nml  
Left Infraspinatus SupraScap C5-6 Incr 4+ None None Nml Nml Incr Reduced Unstable  
Left Cervical Parasp Low Rami C7-8 Nml Nml None None NA NA NA NA NA  
30-year-old patient referred for an electrodiagnostic study to evaluate left arm weakness and numbness.
Medical history significant for a left clavicle fracture in 2017 with malunion.  On January 28, 2019, the left clavicle fracture was treated with open reduction internal fixation.  Patient received regional anesthesia prior to surgery.
When patient woke from surgery, she complained of left-sided lateral neck pain.  She complained of numbness and weakness of the left arm after completion of regional anesthesia. 
Patient completed electrodiagnostic study on February 25, 2019.
Prior to the study, patient completed MR left brachial plexus.  The study indicated normal signal within the plexus, no obvious compression of the plexus, soft tissue edema below the fracture site/surgery consistent with postoperative change.
No other medical history.

Spurling sign absent
Motor: Right upper limb normal.  Left shoulder abduction 1, external rotation 1, elbow flexion, wrist extension, finger extension, finger abduction, thumb opposition absent.
Sensory: Light touch decreased throughout left upper limb and extremity with painless paresthesia over left medial forearm.
Reflexes: Right/left biceps 2/absent, brachial radialis 2/absent, triceps 1/absent, patellar and Achilles 2/2.
Hoffman sign absent.  Plantar responses flexor and no clonus.
Gait and balance normal.

The tabular data included in the post is the patient's nerve conduction and electromyography results.
The left upper limb sensory and motor responses are preserved but abnormal when compared to right side responses.
Significant active denervation of multiple left upper limb muscles.
Normal left cervical paraspinal examination at rest.

I felt the abnormal findings were best explained by an acute to subacute severe left brachial plexopathy based on the abnormal left upper limb sensory responses, denervation of multiple upper limb muscles and normal paraspinal examination.

I was surprised by the preservation of the left upper limb sensory responses  with the degree of denervation on needle examination.  I have studied a number of traumatic and nontraumatic brachial plexopathies.  The preservation of the left upper limb sensory responses is not characteristic of prior experience.
Stimulation of the brachial plexus at Erb's point to look for conduction block across the clavicle would have been helpful.  The patient recently completed left shoulder surgery and would not tolerate that examination.
Needle examination of the left serratus anterior would help determine whether there was involvement of the cervical nerve roots.

Has anyone had a similar experience with brachial plexopathy?
I was concerned there could be a coexisting cervical radiculopathy or polyradiculopathy.
I requested cervical spine MRI for additional evaluation.
I am concerned about the patient's prognosis for recovery.  Typically, preserved sensory and motor responses indicate a better prognosis.  The degree of denervation and lack of motor unit activity on electromyography concerned me (realizing the injury is less than 3 months duration).

Thanks for your assistance.

David Speach

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