Læknablaðið - 15.11.1993, Blaðsíða 45

LÆKNABLAÐIÐ 1993; 79: 375-376
375
NÝR DOKTOR í LÆKNISFRÆÐI
GUÐMUNDUR GEIRSSON
Þann 23. apríl 1993 varði Guðmundur
Geirsson læknir doktorsritgerð við Háskólann
í Gautaborg. Ritgerðin nefnist á frummálinu
»The bladder cooling test. Pliysiology,
guidelines and clinical use in urodynamics«.
Fer ágrip hér á eftir.
The complexity of the neuromuscular control
of micturition makes the system rather
vulnerable. Even a minor lesion or disturbance
may result in an overactive bladder with
a large variety of clinical presentations,
depending on the site and extent of the central
nervous affection.
In 1957 Bors and Blinn noted that bladder
instillation of small amounts of ice-cold water
provoked involuntary detrusor contractions
in patients with chronic upper motor neuron
spinal lesion. They demonstrated that the cold
water response was a reflex involving a spinal
pathway. The neuronal mechanism underlying
the bladder cooling reflex in cats has recently
been identified. It originates from specific cold
receptors in the bladder and urethral walls
and the effect is mediated by unmyelinated
C-afferents in the pelvic and pudendal nerves.
The reflex pathway is primarily segmental,
in contrast to that of the ordinary micturition
reflex, which involves a pontine loop.
The aims of the present study were to
characterise the physiological mechanisms of
the bladder cooling reflex in man and to study
the practical use and the clinical significance
of the bladder cooling test (BCT) in routine
urodynamic investigations.
This investigation comprises retrospective
and prospective studies in 728 adults and
50 children. All of them were studied with
cystometries and BCTs. Variations of the
Key words: Urinary bladder, cooling test, bladder cooling
reflex, ice-water test, urodynamics, neurogenic bladder,
cold receptors, menthol, perception.
standard BCT were also performed in order
to characterise the bladder cooling reflex.
The estimated threshold temperature of the
bladder cooling reflex was 20-33°C, which
is well above the temperatures required for
cold stimulation of nociceptors. The strength
of the human bladder reflex varied inversely
with the bladder temperature. The effect of
menthol, which has a selective potentiating
action on cutaneous cold receptors, was
studied prospectively in another group of
patients. The substance had the same effect on
the human bladder cooling reflex, i.e. a shift
of the threshold temperature towards higher
values. These results indicate that the human
bladder cooling reflex originates from cold
receptors within the bladder wall. The critical
pressure response for a positive test was
25-30 cm H20. Neither the rate of infusion