Spinal cord compression

Thanks to firm 3 for the enthusiasm at today’s bedside teaching.

We saw a gentleman in his 90s who presented with difficulty walking for the past 3 days. He also noted numbness in his right leg distal to the shin over this time. There was no pain, subjective complaints of weakness or change to his bowel/bladder function. He had a recent diagnosis of lung cancer and the concern was about a possible compression of the spinal cord.

We went through the ways a metastasis to the spine may present. We split the symptoms into those related to the bony invasion and those related to the compression of neural bits.

Bony invasion

Severe, horrendous back pain that keeps the patient up at night

Thoracic/cervical pain

Point tenderness

Pain worsened by direct pressure

Pain worsened by straining

Neurological involvement

Motor loss

Sensory loss

Autonomic loss, which can present as bowel/bladder disturbance (often ileus or retention)

‘Off legs’, non specific difficulty walking

Super red flags for cauda equina

Saddle anaesthesia – but be careful about how you ask this question. There is a lesson to be learnt from the case report in the BMJ where a GP simply asked if the patient was numb, which led to the diagnosis being delayed. I have also blogged about the case I discussed with you about a possible cauda equina during my psychiatry job. Ask if it feels different when you sit down or wipe yourself with the toilet paper, not simply whether or not the area is numb. Perianal sensory disturbance occurs in stage 2 of cauda equina, which is much more amenable to treatment than stage 4, where there is perianal sensory loss.

Back pain – one of the earliest signs, but non specific.

Bilateral or alternating leg pain – bilateral or alternating leg pain should always make you think spinal cord or cauda equina. Radiculopathy from simple disc herniation is nearly always unilateral.

Note that we are not saying that all disc hernations are benign. You should advise a patient with disc herniation that although the majority self resolve with no problems, he or she must seek immediate medical attention if symptoms of cauda equina occur. The most common cause of cauda equina is actually disc herniation (occurs in 2% of all disc herniations).

Motor/sensory loss – depending on the exact nerve roots affected. In cauda equina there will only be LMN signs; in conus medullaris there may be both UMN and LMN signs.

Bowel symptoms – any change in bowel habits, but especially ileus symptoms i.e. not passing motions. On PR examination there may be loss of anal tone.  This is a very late sign.

Bladder symptoms – usually retention, and this is a late sign.

What do you do if you think a patient has a spinal metastasis?

1. Assess the severity. The three grades of severity correspond to a) just bony pain b) neurological involvement and c) if emergency treatment could be planned for this condition e.g. cauda equina

2. Discuss with your senior immediately. This patient may need high dose dexamethasone to reduce the swelling around the tumour. There is a limited role for bisphosphonates in breast cancer and myeloma (and sometimes prostate cancer).

3. Ensure adequate analgesia

4. Arrange MRI with the appropriate degree of urgency having discussed with your senior. They may consider issues like the patient’s desired ceiling of care, life expectancy and fitness for intervention.

According to NICE:

Perform MRI of the whole spine in patients with suspected MSCC, unless there is a specific contraindication. This should be done in time to allow definitive treatment to be planned:

– within 1 week of the suspected diagnosis in the case of spinal pain suggestive of spinal metastases,

– within 24 hours in the case of spinal pain suggestive of spinal metastases and neurological symptoms or signs suggestive of MSCC

– occasionally sooner if there is a pressing clinical need for emergency surgery

The treatment from here is essentially surgical, radiotherapy or conservative.

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Cord lesions

I thought it would be helpful to recap the anatomy and work out the clinical consequences of some of the cord syndromes we spoke about today: