Case Report
A 31 years old female presented in 2008 with the chief complaints of lower
back pain and right buttock pain, along with difficulty in falling asleep
because of the severe pain in the leg with a left sided sciatica.
For the past history, she had discectomy in 1998 at L5/S1 with prolonged
rehabilitation but returned to work within 12 months.
Onset
On the physical examination, it was determined that the motor and sensory
nerve functions along L5 nerve root was marginally involved with weakness of
EHL and a straight leg raising was positive at 30 degrees. MRI confirmed
L5/S1 disc protrusion causing L5 nerve root irritation.
There was some improvements of the symptom until four days after the
surgery, but then the patient complained of a progressive tingling sensation in
both legs and difficulties in micturition and defecation with a saddle sensory
decrease and a decrease of the anal sphincter tone. She showed some
significant weakness in the ankle, and knee weakness with numbness in the
left leg. There was decreased anal tone.
Repeat MRI
mild change in his symptoms several days after the surgery, but he suffered
from constant neurogenic pain along with the difficulty in micturition and
defecation and he was unable to walk normally because of the weakness and
tingling sensation in both legs. Thus, we performed electromyography of the
lower extremities and the results showed diffuse bilateral lumbosacral
radiculopathies. The 3-phase bone scan showed non- specific findings.
However, there was no evidence of focal disc herniation and compression of
the thecal sac or nerve root, and the fixation device was in good position
according to the contrast enhancement lumbar MRI findings (Fig. 1). We
carried out various treatments with taking adhesive arachnoiditis, a battered
nerve root or scar adhesion and the psychological compensation from the
labor injury into account as the cause of the post-operative syndrome in the
lumbar spine. We administered oral corticosteroid (Dexamethasone®; Pacific
Pharmaceuticals, Seoul, Korea) due to the neurogenic symptoms for a fixed
period, and the patient continued his exercise and physical therapy, and he
received medication (anti- inflammatory drugs, analgesics, and gabapentin
[Neurontin®; Pfizer, New York, USA]) at the same time. We also
administered medication for the difficulty of micturition along with
conducting uro-dynamic and bladder examinations at the urology center and
we provided psychological consultation and antidepressants at the
neuropsychology center. Furthermore, the patient received local injection
therapy that included epidural block at the pain clinic, but he did not show
any satisfying improvement of the symptoms.
DIAGNOSIS; Cauda Equina Syndrome [CES] following post discectomy
Pathophysiology of CES
In adults, the spinal cord terminates between the T12 and
L2 vertebrae, most commonly at the level of the L1
vertebral body.
The conus medullaris and is attached to the coccyx by the
filum terminale.
The conus contains the cell bodies and dendrites of the
exiting L5 to S3 nerve roots.
The cauda equina is a collection of peripheral nerves (L1
to S5) in a common dural sac within the lumbar spinal
canal.
Bladder innervation
Neurogenic bladder dysfunction is an essential element of CES.
Parasympathetic: S2,3,4 [contraction of detrusor and relaxes internal sphincter
Sympathetic: hypogastric plexus (T11-L3). Reverse of Parasympathetic
Somatic nerves [the pudendal nerve S2,3,4. The external sphincter of the bladder is a
striated muscle
Pathogenesis
The nerve damage in CES may be the result not only of direct mechanical compression
but also a secondary, so-called closed compartment syndrome. Rydevik demonstrated
that mechanical compression of the nerve roots causes an intraneural edema, which
directly causes nerve damage and secondarily results in an increase in intraneural
pressure.
Clinical
1. Sensation
Urinary retention (S2-S4 nerve roots). Measurement of a
patient’s post void residual volume provides an accurate
assessment of urinary retention. [Kostuik ]
Reflexes: Anal wink, Anal tone, look for voluntary
anal contraction, bulbocavernous reflex [S1-3]
Look for Pinprick sensation
Usually they preserve light
touch
Discussion
Bilateral radiculopathy or sciatica are early stages of CES and indicate a high risk of
development of advanced CES. Electrophysiological abnormalities and reduced
saddle sensation [to prick pin sensation] are indices of early diagnosis.
Early CES
Patients at the preclinical and early stages have better functional
recovery than patients in later stages after surgical decompression.[ Acta
Orthopaedica 2010; 81 (3): 391–395]
Fully blown CES:
CES refers to impairment of the cauda equina and clinically it may
manifest as low back pain, saddle anesthesia, bilateral sciatica, motor
weakness of the lower extremities, paraplegia, and bowel, bladder, or
sexual dysfunction (Byrne 1993).
Conversely, patients with extensive nerve damage from severe and
prolonged compression (group 4) were not helped by surgical
intervention
Shia classification [Acta Orthopaedica 2010; 81 (3): 391]
Group 1
Low back pain with only BCR (bulbo-cavernosus
reflex) and ICR (ischio-cavernosus reflex) abnormalities
and no typical symptoms of CES.
Group 2
He had slight saddle sensory disturbances and bilateral
sciatica.
Group 3
Patients had severe saddle sensory disturbances,
bowel and/or bladder dysfunction, motor weakness of
the lower extremities and reduced sexual function.
Group 4 Patients had no saddle sensation, no sexual function,
and uncontrolled bowel function.
Cauda Equina after Disketomy
Incidenc 0.5%
Kardaun [J Spinal Disord 1990;3:30–8] have shown a 3.7% over all complication
rate after surgical treatment for lumbar disc herniation. Postoperative cauda
equina syndrome (CES) ac- counted for 0.5%[J Bone Joint Surg [Am]
1986;68:386 –91].
When to suspect
1, A high index of suspicion is necessary in the postoperative spine patient with
back and/or leg pain refractory to analgesia, especially in the setting of urinary
retention [J Am Acad Orthop Surg 2008;16:471- 479 ]
2. Bilateral sciatica: early post op period. Look for any changes in the saddle
area
Causation
In lumbar diskectomy, injury to the cauda equina can occur during surgery from
direct damage to the nerves, especially from excessive retraction of the dural
sac, or postoper- atively as a result of the development of a hematoma or related
to dural tear.
Common features
Henriques [Spine 2001; 26:293-297] reported on five cases of postoperative CES
following surgery for lumbar disk herniation.
All five patients had a relative spinal stenosis at the involved level.
Usual presentation is within 24 hours [1/5 may be seen at 4th day]
Neurology is due to ischaemia contributed by venous congestion
4. Postoperative magnetic resonance imaging did not show the cause of the
cauda equina syndrome, nor could this be established at the reoperation.
Intensity of symptoms: significant bilateral sciatic refractory to analgesics
Treatment
Most authors seem to agree that the treatment of CES is a wide decompression within
24 hours.
References
McLaren [Clin Orthop Relat Res 1986;204:143-149]
2. Jensen[Neurosurg Focus 2004;16:E7]
Henriques [Spine 2001; 26:293-297]
J Bone Joint Surg [Am] 1986;68:386 –91