Lower back pain
and bladder
dysfunction
A 36 year old
man presented
with progressive
low back pain
and bladder
dysfunction. He
had had periods
of non-specific
back pain for
more than a
year. In the
past two weeks
the pain had got
worse, radiating
from the left
dorsolateral
thigh to the
lateral site of
his left foot.
For three days
he had had
difficulties
initiating
micturation, and
the flow had
weakened. He
felt numb
sensations in
the left
scrotum, the
perineal region,
and on the
lateral site of
the left foot.
He also noticed
muscle weakness
in the left
foot. He had no
history of
trauma or recent
disease.
General
physical
examination
indicated a
healthy young
man.
Neurological
examination
showed paralysis
of the left foot
extensors, motor
weakness of left
foot flexors
(grade 2-3), and
sensory deficits
from the medial
leg to the
dorsal lateral
foot. The
patellar
reflexes were
vivid on both
sides (left more
than right). The
ankle jerk was
absent on both
sides and
plantar flexes
indifferent.
Rectal
examination
indicated saw
saddle
anaesthesia and
low sphincter
tone. Normal and
crossed straight
leg raising
tests were
positive at 50°
at the left
side.
Questions
(1) What
worries you most
in this case?
(2) What is
the term for
this complex of
symptoms?
(3) What is
the differential
diagnosis?
(4) What
would you do
next for this
patient?
(5) What are
the features
seen in the
magnetic
resonance image
(figure1)?
Answers
(1) Alarms
should go off
when a patient
presents with
difficulties in
urine and
sensory loss in
the buttock
region. Other
warning signs
are the
decreased
sphincter tone
and the motor
and sensory loss
in the left leg
accompanied by
acute worsening
of backache.
(2) Cauda
equina syndrome
is caused by
narrowing of the
spinal canal:
nerve roots
become trapped
and start to
dysfunction. The
array of
symptoms can
guide the
investigator to
the level of
compression.
(3) All
conditions
resulting in
compression can
explain cauda
equina syndrome.
Consider trauma,
disc herniation,
spinal stenosis,
neoplasms,
spondylolisthesis,
inflammatory
conditions, and
iatrogenic
conditions.
(4) Start by
taking an
accurate history
and a clinical
examination to
narrow the
differential
diagnosis. You
should already
suspect the
diagnosis of
central disc
prolapse.
Magnetic
resonance
imaging is the
best diagnostic
investigation
because it can
depict soft
tissues. Consult
the orthopaedic
or neurological
surgeon
immediately for
further
treatment.
(5) The
magnetic
resonance image
in the figure1
shows a massive
herniated disc
at the level of
L4-L5 into the
spinal canal.
This view also
shows some
bulging of the
disc at the
level of L3-L4
and minor
discopathy in
the adjacent
levels.
(6) Cauda
equina syndrome
to central disc
prolapse at the
level of L4-L5.
(7) The
suspected
diagnosis of
central disc
prolapse causing
cauda equina
syndrome is an
investigative
and surgical
emergency.
Surgical
decompression
should be
performed as
soon as possible
to stop further
neurological
loss and improve
clinical
outcome. 1 2 3. The
preferred method
of decompression
is laminotomy
and partial
discectomy.
