345hemorrhage and swelling secondary to blunt trauma, and swellings such as ganglion
cysts or lipomas. However, the commonest cause in recent years has been identifi ed
as infl ammatory changes in the hand’s fl exors muscle tendon sheath, attributed to
the expanding use of electronic gadgets such as mobile phones, tablets, and comput-
ers. In addition, a wide variety of metabolic diseases, systemic illnesses, and aber-
rant anatomic structures also have been described as causes of CTS.
However, the patients’ symptoms and disease severity remain the same and can
be linked to the pathophysiologic changes occurring in the median nerve in
response to compression [ 65 , 66 ]. The initial impact is reduction in the epineural
blood fl ow, which occurs at 20–30 mmHg compression. In CTS patients, the least
intracarpal canal pressure recorded was 33 mmHg and with wrist extension it can
go up to 110 mmHg [ 67 ]. Persistent or increased pressure ultimately causes edema
in the epineurium as well as endoneurium. If pressure of 50 mmHg has been
applied for 2 h, it will cause epineural edema, and if applied for 8 h, it will lead to
increase in peri-neural congestion (Fig. 13.4 ) and consequently increase in endo-
neural fl uid pressure up to fourfold, which eventually will block axonal transport
[ 37 ]. As further injury occurs to the capillary endothelium, more protein leaks out
into the tissues, which gets more edematous, and a vicious cycle starts. The effects
are most pronounced within the endoneurium, since more exudate and edema
accumulate there, being unable to diffuse across the perineurium. The perineurium
resists pressure changes because of its higher tensile strength and acts as a diffu-
sion barrier creating in effect a “compartment syndrome” within the nerve [ 68 ].
These pathophysiologic changes mirror the patient’s symptoms severity as well as
neurological fi ndings that range from tingling, numbness, and pain, down to loss
of sensation.
As it is diffi cult to assign severity on the basis of the symptoms, questionnaires
offered a way to calibrate the severity of CTS. The BCTQ Severity Scale is the most
common tool used to assess the global severity. A systematic review [ 16 ] of the
Boston CTS questionnaire revealed moderate correlations reported with measures
of symptom severity as well as post-management relief, generic measures of health
status, quality of life, and satisfaction [ 69 , 70 ]. The CTS-PROMs severity scale is
the only questionnaire to raise the relative severity measure for each domain
assessed. Attaining a high relative score (>1) indicates that this symptom was
prominent relative to the other symptoms. This should be taken into consideration
on assessment of the possible underlying pathology or setting up the treatment plan.
PROMs and Management Outcomes
Treatment options available for CTS patients include either conservative or surgical
interventions. However, it is not known which patients are more likely to benefi t
from what treatment. Also the rate to what extent the patient has improved is also
important, not only as quantity but also as a quality measure. In view of the absence
of the “gold standard” to diagnose or monitor CTS patients, patient reported
13 PROMs for Carpal Tunnel Syndrome