ABSTRACT
Diagnosis and documentation of brachial plexus compression in the thoracic inlet,
“thoracic outlet syndrome”, remains difficult because the syndrome complex overlaps
that of patients with cervical disc disease, intrinsic shoulder pathology, and peripheral
nerve compression. While traditional electrodiagnostic testing can identify cervical
radiculopathy and the rare isolated lower trunk compression, it cannot identify brachial
plexus compression in the thoracic inlet. In 2000, neurosensory testing with the Pressure-Specified
Sensory Device (PSSD) was applied to this diagnostic dilemma, demonstrating a significant
increase in the one-point static touch cutaneous pressure threshold between controls
and patients, when the index finger (upper trunk) and little finger (lower trunk)
were tested with the hands at rest and after provoking the plexus by elevating the
hands above the head. In the present study, this approach has been extended to include
two-point static touch thresholds with the PSSD, and pinch and grip strength (Digit-Grip).
Sixteen controls (mean: 34.2, range: 11 to 48 years) were tested and the 99 percent
upper confidence limit calculated for percent change after elevation of the hands
for 3 min. Forty-one patients symptomatic for brachial plexus compression (mean: 41.0,
range: 21 to 62 years) were tested. The clinical severity of the plexus compression
was dichotomized as either “severe” or “not severe” judged by the Roos and Tinel sign.
Results demonstrated that when five or more of the eight possible neurosensory and
motor test results were > 99 percent normal confidence limit for change, this testing
has a sensitivity of 82 percent, a specificity of 100 percent, and a positive predictive
value of 100 percent for the diagnosis of clinically severe brachial plexus compression.
Seventeen patients who were in the “severe” category prior to surgery, were tested
before and after plexus neurolysis and anterior scalenectomy. All 17 patients were
clinically improved and in 16 of these patients, postoperative neurosensory and motor
testing returned to a normal pattern (no significant increase in thresholds with hand
elevation). It is concluded that neurosensory (PSSD) and motor testing (Digit-Grip)
can help in the diagnosis and documentation of brachial plexus compression.
KEYWORDS
Brachial plexus compression - “thoracic outlet syndrome,” - diagnosis - documentation
