Portal de Periódicos da CAPES

Anaesthesia for chronic spinal cord lesions and multiple sclerosis

1998; Wiley; Volume: 53; Issue: 8 Linguagem: Inglês

10.1046/j.1365-2044.1998.0584e.x

1365-2044

J W H Watt,

Spinal Hematomas and Complications

I was pleased to see the useful and wide-ranging review of anaesthesia for chronic spinal cord damaged patients by Hambly & Martin (Anaesthesia 1998; 52: 273–89) and would like to make a few additional recommendations. The authors rightly emphasise the role of the renin–angiotensin system in the postural maintenance of the blood pressure and it follows that ACE inhibitors must be avoided in these patients and also that β2 agonists may cause systemic hypotension even occasionally when nebulised [1]. I would like to stress the need to bear in mind that some patients coming to the operating theatre may not be having continuous catheter drainage of the bladder and that inadvertant distension of the bladder peri-operatively can be damaging to the neuromuscular elements within the bladder wall. Peri-operative dehydration can lead to urinary tract infection so that intravenous fluids are usually required both for this reason and in anticipation of hypotension on induction of anaesthesia. Fluid therefore has to be carefully administered and for longer operations bladder drainage secured. Whilst I think it is understandable to be hesitant in offering spinal anaesthesia to a patient with an incomplete lesion, there is no evidence that intrathecal bupivacaine is neurologically damaging. In a personal series of 150 urology patients, 44 had had spinal anaesthesia and though there was commonly no decrease in blood pressure, the greatest reduction was observed in one C5 Frankel A tetraplegic patient 5 min after induction, going from 120/65 mmHg to 85/40 mmHg [2]. One advantage of spinal anaesthesia in urology is the prevention of priapism which can be troublesome even under deep general anaesthesia. I have found that much the best way to treat this is with increments of 25 μg of salbutamol [3]. The anxiety surrounding intrathecal or extradural anaesthesia in neurological cases has extended to patients with multiple sclerosis (MS) [4, 5]. Four patients who recounted to me their personal experiences of deteriorations in their condition following general anaesthesia prompted me to use spinal anaesthesia or general anaesthesia, excluding nitrous oxide in them and in another four patients with the disease. There was no subjective neurological deterioration in five patients having general anaesthesia with volatile agents or propofol and neither were there exacerbations in the group having spinal anaesthesia. The implication of nitrous oxide in neurological damage arises both from its role in the time-weighted inhibition of vitamin B12 [6] and its known link with myelopathy and its recently observed association with multiple sclerosis [7]. The difficulty in collecting a series of patients in whom one might be able to measure levels of homocysteine and methyl malonate means it will be some time until this hypothesis could be refuted. In the meantime, I would propose that nitrous oxide be avoided in multiple sclerosis except for short procedures.