This patient has bowel and bladder dysfunction; examine the lower limbs.
· Ask the patient whether there is pain, usually projected to the perineum and thighs (this is root pain in the dermatomes L2 or L3 or S2 or S3,whereas pain in L4, L5 or S 1 distribution is commonly attributed to disc disease).· Determine whether there is a history of trauma and 'neural claudication' (where the patient develops root pain and leg weakness, usually afoot-drop while walking; this rapidly recovers on resting).· Pain in the anterior thigh, wasting of the quadriceps muscle, weakness of the loot invertors (due to L4 root lesion) and an absent knee jerk.· Obtain history of leukaemia or prostatic carcinoma (primaries for bony metastases).
· Flaccid, asymmetrical paraparesis.· Knee and ankle jerks are diminished or absent.· Saddle distribution of sensory loss up to the E1 level.· Downgoing plantars.
This patient has flaccid paraparesis with saddle anaesthesia due to cauda equina syndrome (lesion) caused by a compressive lesion (aetiology).
What is the relationship of the spinal cord to the vertebrae?
The spinal cord extends from the foramen magnum to the interspace between the 12th thoracic (dorsal) and first lumbar spines,although the thecal membranes may extend down the body of the second sacral vertebra. To determine the spinal segments inrelation to the vertebral body: for cervical vertebrae add 1, for thoracic I-6 add 2, for thoracic 7-9 add 3, and the lumbar segments lieopposite the 10th and 1 Ith thoracic spines and the next interspinal space. The first lumbar arch overlies the sacral and coccygealsegments. (Remember that the sacral segments are com-pressed into the last inch of the cord known as the conus medullaris; thelatter is located behind the ninth thoracic to the first lumbar vertebra.)
At which vertebral level is the lesion in cauda equina syndrome?
A lesion in the spinal canal at any level below the tenth thoracic (dorsal) vertebra can cause cauda equina syndrome.
How would you differentiate between cauda equina and conus medullaris syndrome?
The cauda equina consists of' lower spinal roots (T12 to S5) and hence a lesion causes lower motor neuron signs, whereas theconus medullaris is the lowest part of the spinal cord and lesions result in upper motor neuron signs. Lesions involving both conusand cauda result in a mixed picture.
What are the causes of cauda equina syndrome?
· Centrally placed lumbosacral disc or spondylolisthesis at the lumbosacral junction.· Tumours of the cauda equina (ependymoma, neurofibroma).
What are the types of cauda equina syndrome in adults?
· The lateral cauda equina syndrome: pain in the anterior thigh, wasting of the quadriceps muscle, weakness of the foot invertors(due to L4 root lesion) and an absent knee jerk. Causes include neurofibroma, a high disc lesion.* The midline cauda equina syndrome: bilateral lumbar and sacral root lesions. Causes include disc lesion, primary sacral bonetumours (chordomas), metastatic bone disease (from prostate) and leukaemia.