Cauada equina syn

Cauda EquinaThe term cauda equina, Latin for horses tail, refers to the terminal portion of the spinal cord and roots of the spinal nerves beginning at the first lumbar nerve root.

Cauda equina syndrome (CES) is a compression of some or all of these nerve roots, resulting in symptoms that include: Bowel and bladder dysfunction, Saddle anesthesia, Varying degrees of loss of lower extremity sensory and motor function.

Although a precise definition of CES has not been well established, most authors believe that an element of bladder dysfunction is required for the diagnosis.

AnatomyThe caudal end of the spinal cord is the conus medullaris and is attached to the coccyx by a thin non-neural filament, 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.

During development, the spinal cord appears to migrate proximally because of the relatively greater growth of the vertebral spinal column. As a result, the first nerve roots that contribute to formation of the cauda equina, the L1 nerve roots, actually exit the spinal cord at the T10 vertebral level.

Bladder Anatomy

Neurophysiologically, lesions involving the cauda equina are lower motor neuron lesions.

Therefore, patients with CES may demonstrate varying degrees of lower extremity muscle weakness and sensory disturbance as well as decreased or absent reflexes.

Neurogenic bladder dysfunction is an essential element of CES. The detrusor urinae muscle and internal sphincter of the bladder are smooth muscles. They are controlled by the parasympathetic nervous system via the S 2-4 nerve roots and the sympathetic nervous system via the hypogastric plexus (T11-L3).

The external sphincter of the bladder is a striated muscle that is controlled by the pudendal nerve, which arises from the S2-4

Bladder dysfunction can be divided into two broad categories: retention and incontinence.

CES causes a lower motor neuron lesion that interrupts the nerves forming those reflex arcs. Consequently, patients lose both sensory and motor innervation to the bladder.

The loss of contraction and sensation leads to urinary retention and eventually to overflow incontinence.

Aetiology AcuteTraumaInfectionHerniated nucleus polpususSubdural /epidural haemorrhageVetebrae collapse due to metastatic tumourIatrogenic ChronicExtrinsic tumourPrimary tumourSpinal stenosisChronic central disc herniationAbscess , tuberculoma

NeoplasmCommon in primary tumour: Ependymomas and neurofibromaMetastatic tumour (relatively rare to cause CES) eg: only 0.7% of lung mets to spine have CESPrimary tumour of sacrumMain symptoms is pain (resting pain or night pain)

CLINICALMainly divided into 2 category:Cauda equina syndrome with urinary retensionIncompplete cauda equina syndrome (reduce urinary sensation, reduce desire to void, poor stream)Cauda equina syndrome is used only when these include impairment of bladder, bowel, or sexual function, and perianal or saddle numbness.

Patients with CES may present with a varying combination of signs and symptomsLow back pain, (local or radicular pain) Groin and perineal pain, radicular pain, Lower extremity weakness, Hyporeflexia or areflexia,

Sensory deficits, Perineal hypoesthesia Saddle anesthesia,

Loss of bowel or bladder function.Loss of sexual function

Back pain: characteristically severeBilateral sciatica is strongly associated with CES

CLINICAL [cont.]BLADDERBladder dysfunction is a required element.Early bladder dysfunction can be subtle and involve difficulty initiating the urinary stream.Dysfunction may then progress to urinary retention Eventually overflow incontinence, as mentioned.

Before the development of CES, patients often will have prodromal symptoms of low back pain and/or unilateral sciatica, reflective of uncomplicated lumbar disk herniation or stenosis.

Back pain is present and characteristically severe, but it may be resolving or even absent in patients with delayed presentation. Bilateral sciatica is strongly associated with CES, but unilateral lower extremity pain is a more frequent symptom at the time of initial presentation.

CLINICAL [cont]Saddle Anesthesia: Dense sensory loss involving the perineum, buttocks is a relatively late sign of established CES and may indicate poor potential for recovery of normal bladder function.

2 distinct clinical presentations of CES: acute and insidious.

The acute presentation was characterized by the sudden onset of severe low back pain, sciatica, urinary retention requiring catheterization, motor weakness of the lower extremities, and perineal anesthesia.

The insidious presentation was characterized by recurrent episodes of low back pain occurring over periods of a few weeks to years, followed by the gradual onset of sciatica, sensorimotor loss, and bowel and bladder dysfunction. This latter presentation often occurs in the setting of long-standing spinal stenosis.

SIGNSSensation to pinprick in the perianal region (S2-S5 dermatomes), perineum, and posterior thigh is performed. These patients typically have preserved sensation to pressure and light touch, so if discrimination is not made between pinprick and light touch sensation, then the diagnosis of CES may be missed.

A rectal examination is performed on all patients with potential CES to assess the tone and voluntary contracture of the external anal sphincter. Decreased rectal tone is often an early finding in a patient with CES.

Both the anal wink test and a bulbocavernosus reflex should be evaluated. The bulbocavernosus reflex is a segmental polysynaptic reflex with crossover in the sacral spinal cord (S2-4). The reflex is performed by applying pressure to the glans penis or clitoris and/or traction on the Foley catheter.

Bulbocavernous reflex

Cornus medullarisCauda equinapainB/L, symetrical, perineal areaSevere, asymmetryRadicular painUnusualUsual Sensory deficitSaddle, B/LSaddle, asymmetryMuscle lossSymmetrical, mild weakness, fasciculationAsymmetrical, atrophy, flaccid paralysis, no fasciculationImpotence commonLess commonSphincter dysfunction bowel and bladderPresented earlyPresented lateSeverity symptomsUsually not severeUsually severe

Cornus medullarisCauda equinaVetebrae Level L1-L2L2-sacrumReflexAreflexia(if epiconus involve, patella reflex abscent, bulbacarvenosus reflex spared)Areflexia, bulbacarvenosus reflex abscent

OutcomeLess favourableMore favourable

Clinical diagnosis of cauda equina syndrome even by resident neurosurgeons has a 43% false positive rate, so accurate confirmatory imaging is important. Magnetic resonance imaging (MRI) is the imaging modality of choice.Urgent MRI is recommended for all patients who have new-onset urinary symptoms with associated back pain or sciatica.MRI with gadolinium contrast of the lumbosacral area is the diagnostic test of choice to define pathology in the areas of the conus medullaris and cauda equina

Fig 2 Left: MRI scan showing compression of the cauda equina (arrow) due to a large posterior disc herniation at L4/5. Right: MRI scan showing a large disc herniation at L5/S1 (arrow) bulging posteriorly and compressing the cauda equina syndrome

Fig 3Top: Axial cross sectional MRI view at the level of L5/S1 of a patient with cauda equina syndrome showing a large irregular disc herniation (arrow) occupying most of the vertebral canal. Bottom: By contrast, a cross sectional MRI view at L5/S1 in a patient without cauda equina syndrome showing an unobstructed vertebral canal (arrows from top down: body of S1 vertebra; vertebral canal containing cauda equina with no compression; spine of S1)

EMG: shows evidence of denervation. Can also help in monitoring recovery.CXR: TRO malignancy or TBDuplex ultrasound to rule out vascular compromiseNCS: to rule out distal peripheral nerve lesionSomatosensory evoked potential: TRO multple sclerosisLP: to rule out inflammatory dsESR: inflammatory ds

Measurement of a patients post void residual volume provides an accurate assessment of urinary retention.

Urodynamic studies should be performed in all patients both preoperatively and postoperatively, such a comprehensive preoperative evaluation is often not feasible, may delay treatment, and is not widely practiced.

The postoperative spine patient presents a unique clinical scenario to the practitioner. Increasing back pain followed by unilateral or bilateral leg pain may be potential signs of developing CES.

TreatmentConsensus exists that the most appropriate treatment of CES Recommended procedures range from simple microdiskectomy to a wide laminectomy, diskectomy, and open inspection of the nerve roots within the dural sac.

Timing of SurgeryThe optimal timing of surgery following diagnosis of CES remains a topic of great controversy.

Traditional practice has been to proceed with surgical decompression in a timely fashion, preferably within 24 hours.

Adequate Pain managementAnticoagulant

Intermittent self catheterization Manual evacuation of rectum

CASE 1This 34-year-old woman had been healthy, apart from a 10-year history of chronic low back pain. She presented at the Emergency Room with worsening of the low back pain over the last 10 days, but because, in particular, on the previous day, she had developed a new, severe pain in the perineal and sacral area. A few hours later, she noted numbness in the perineum and increased urinary frequency. She felt that she was not emptying her bladder completely. She also had some increased frequency of bowel movements and defecation was painful. She denied any weakness in the legs.

On examination, she was in pain. The abnormalities were restricted to the lower limbs. Straight leg raising was markedly limited bilaterally. Cross SLR test was positive. Power was normal in the legs. The right ankle reflex was absent. Sensory examination showed marked diminution of light touch and pin prick in the perineal and perianal areas. A rectal examination showed reduced rectal tone.

A diagnosis of a central lumbosacral disk herniation was made and a CT scan was performed. This showed a large posterior disk herniation at L4-L5 (Figures 1 and 4). She underwent surgical diskectomy within hours. The following day, her back pain was considerably better and sensation in the perineum and bowel function gradually returned to normal. Bladder function was normal from the first postoperative day.

Comment: This history is characteristic of an acute central disk herniation causing cauda equina compression. Urgent imaging for confirmation of the diagnosis and urgent surgery are required in order to optimize the patients chances of a good recovery of bladder and bowel function.

CASE 2This 73-year-old man had suffered from diabetes mellitus which had been controlled by oral hypoglycemic agents for the last 18 years. He was referred for evaluation with a history of pain in the anal, sacral, right gluteal area, and the posterior aspect of the upper right thigh over the last 3 years. The pain was consistently brought on by lying down and relieved by standing. He had to sleep in a reclining chair. He denied any motor or sensory symptoms in his legs. However, for 3 years, he had had erectile dysfunction, would have to get up three times at night to urinate, and had developed constipation that required regular laxatives. A urological evaluation showed no prostatic hypertrophy, and a thorough gastroenterological evaluation revealed no explanation for the constipation.Neurological examination was completely normal except in the lower limbs. Here the power was normal, but the ankle reflexes were absent, which could have been due to diabetic neuropathy or to bilateral S1 radicular involvement. A careful sensory examination with light touch and pin prick showed no abnormalities anywhere in the legs, and, in particular, this was normal in the sacral dermatomes. Rectal tone was normal.

A myelogram and CT-myelogram scans were performed and these showed an intradural lobulated mass opposite the lower border of the L5 vertebra causing complete obstruction of the sub-arachnoid space. Surgical exploration revealed that the tumor, although largely intradural, did have some extension through the dura and, indeed, through the posterior lamina of the sacrum and into the muscles overlying the sacrum. The tumor was resected almost entirely, which involved removing a few filaments of sacral spinal nerve roots. The pathology of this tumor was greatly debated, the consensus being an atypical schwannoma.

Postoperatively, the patient had urinary retention requiring catheterization. This improved, but from then on, he had to self-catheterize twice a day. The partial constipation and erectile dysfunction continued unchanged. Six years later, the patient had the recurrence of pain, less ability to micturate, requiring increased bladder self-catheterizations, and a marked worsening of the constipation requiring increased laxatives, suppositories, and enemas. Re-examination showed signs of a mild peripheral neuropathy in the feet, presumably due to his diabetes. However, there was a clear reduction in sensation in the perianal area and there was a reduction in anal tone. Further radiological studies showed a large soft-tissue mass producing destruction of the majority of the sacrum and spreading to the soft tissues both anteriorly and posteriorly to the sacrum. A biopsy was performed and again the pathology was debated, but the consensus was that this represented a malignant schwannoma. The patient had radiotherapy and there was some reduction in the bulk of the tumor as seen on CT scanning. The pain disappeared, but the bladder and bowel dysfunction remained unchanged. The patient died 8 years later of unrelated causes.

Comment: The pattern of pain in this patient, particularly pain that is worsened by lying and relieved by standing, is characteristic of cauda equina mass lesions. Although the patients erectile, bladder and bowel symptoms at the time of presentation could have been attributed to his long-standing diabetes mellitus, in the context of this type of pain, it was thought to be due to involvement of the cauda equina

Symptoms depends on extend of hernia, size of canal, number of nerve root*