Introduction

Amyotrophic lateral sclerosis (ALS) is a progressive neurological disorder that mainly affects male patients between the fifth and sixth decades of life, with an incidence of 1:50000.¹ It is characterised by degeneration of higher and lower motor neurons because of degenerative changes in lateral corti-cospinal tracts of the spinal cord and, consequently, muscle denervation.²

ALS, or Lou-Gehrig disease, is extremely rare in pregnant women. Only some 12 cases have been reported of pregnant women with ALS since 1993. It is important to highlight that respiratory demands during pregnancy may result in acute respiratory failure in patients with ALS. For this reason, it is recommended to establish baseline respiratory function early on in pregnancy and ensure regular follow-up. In some cases, vaginal delivery maybe expected because the perineum is not affected and uterine dynamics is not altered.³ However, physiological changes that become more intense towards the end of pregnancy, such as reduced residual functional capacity resulting from lower residual volume due to diaphragm displacement by the pregnant uterus, may worsen the mother's respiratory status secondary to progressive muscle weakness inherent to the disease. This could lead to the indication of early caesarean section.

There are few recommendations in the literature regarding anaesthetic management of women in childbirth with ALS. Epidural analgesia and anaesthesia have been used in these patients with no evidence of worsening of their neurological condition following the procedure. Progressive loss of innervation leads to muscle atrophy and hypersensitivity of acetylcholine nicotinic receptors. These patients are more sensitive to the use of non-depolarising neuromuscular relaxants⁴ and, furthermore, the use of depolarising muscle relaxants is associated with neuro myotonia, rhabdomyolysis and severe hyperkalemia.⁵Becauseofalltheseconsiderations, a pregnant woman with ALS is a true challenge when it comes to peri-operative management and critical care.

Case description

A 38-year-old primigravida 38weeks pregnant diagnosed with ALS some 10 years before was scheduled for category 4 caesarean section by obstetric indication. Upon neurological assessment, the patient presented with progressive muscle weakness, severe dysarthria, dysphagia, preserved superior function, fasciculations in the anterior region of the chest and the tongue, and is emotionally labile.

In terms of muscle function, the patient presented with quadriparesis (muscle strength in upper limbs 2/5 and 2/5 in the lower limbs), hypotonia, generalised laxity, hyper-reflexia and positive bilateral Babinsky sign. In terms of pulmonary function, the chest X-ray showed evidence of moderate fibro emphysema and there was severe restriction on spirometry, leading to a diagnosis of mild respiratory failure. There was absence of cardiovascular symptoms, grade 2 cardiological risk (Goldman score), no functional capacity assessment was made, and there was no evidence of murmurs or cyanosis. Anaesthetic assessment: ASA III, body weight 50 kg, height 155 cm, BMI 20.83, mouth opening 3 cm, thyro-mental distance greater than 6 cm, modified Mallampati grade 3, preserved cervical mobility and mandatory decubitus. Vital signs: heartrate 86bpm, arterial blood pressure 134/92mmHg, respiratory rate 20 rpm, oxygen saturation 95% in room air, and no fever.

The patient and husband were explained the anaesthetic technique, and after discussing the risks and benefits, a sequential combined spinal-edpidural (CSE) was performed.

Before anaesthesia administration, the patient received ranitidine 50mgIV, metoclopramide 10mgIV and dexameth-asone 4 mg IV. Basic ASA monitoring was instituted and advanced airway equipment and aspiration tube were prepared. With the patient in lateral decubitus and following asepsis and antisepsis, the epidural space was identified at the level of L3-L4, 4 cm from the skin; using a N°18 Tuohy needle and the technique of intermittent loss of resistance, the epidural space was reached with no complications. A N° 27 Whitacre spinal needle was then inserted through the Tuohy needle until CSF flow was ascertained, and hyperbaric bupi-vacaine 6 mg plus fentanyl10 were injected. Finally, a N° 20 multi-orifice epidural catheter was put in place and fixed 9 cm from the skin.

The catheter aspiration test was negative and the decision was made not to use a test dose; sensory anaesthetic level was obtained up to T7.With the patient in supine decubitus and15° uterine lateralisation, 0.25% isobaric bupivacaine in 10ml was administered through the epidural catheter 5 min after the intrathecal injection, achieving sensory block ofT5 after 5 min.

The goal was to achieve adequate anaesthetic level while minimising the haemodynamic changes associated with a single-dose spinal technique. Oxygen was delivered through a reservoir mask in order to reach a level of oxygen saturation greater than 96%, and surgery was initiated. There were no heart rate or blood pressure variations greater than 10% from baseline, and there was no need for vasopressor use.

Childbirth occurred 15 min after the establishment of the neuroaxial block, with the outcome of a healthy male neonate who weighed 3520g, with a size of 49cm, and an APGAR score of 8 and 9 at 1 and 5 min, respectively. Oxytocin 3 IU IV was administered and the same dose was repeated 3 min later, and an infusion of 3 IU over 1 h was prepared. The surgical procedure continued uneventfully and lasted 21 min, with intermittent aspiration of saliva from the oral cavity. Total blood loss was 400 ml and the patient was administered 1000 ml of saline solution with the result of clear urine diuresis of100ml. The patient was given multimodal analgesia with metamizole 2 g IV and epidural morphine 2 mg.

The patient was transferred to the post-anaesthesia care unit (PACU) where she remained for 3 h with no complications. She was prescribed thromboprophylaxis with enoxaparin 40mg SQ every 24h, starting12h after discharge from the operating room.

Discussion

Pregnancy in patients with ALS is a true challenge for the medical team involved. There are certainly several considerations regarding anaesthetic management, of which respiratory function optimisation is perhaps the most important.

Pre-operative preparation is crucial and must focus on assessment of family and personal history of problems with anaesthesia, assessment of the airway and concurrent medical issues, prophylaxis to prevent aspiration as well as adequate hydration, and basic peri-operative monitoring.

Measures for preventing aspiration and post-operative nausea and vomiting (fasting of more than 8 h, H2 blockers, metoclopramide 10 mg and ondansetron 4-8 mg) must be instituted together with antibiotic prophylaxis in order to diminish the risk of surgical site infection.

There are no clear recommendations for the selection of the anaesthetic technique. However, if general anaesthesia is chosen, it is important to consider potential complications with the airway, and the use of mechanical ventilation. Tracheal intubation is a critical moment because of gestation, some difficult airway predictors and the inability to use muscle relaxants due to the patient's clinical condition. Likewise, motor compromise, dysphagia and respiratory insufficiency could prolong mechanical ventilation which, in our situation, is provided in a maternal intensive care unit, with the associated risk of exposure to infection and prolonged length of stay among other things. However, intravenous general anaesthesia without the use of muscle relaxants may be an option for anaesthetic management.

Although there is little evidence in the literature regarding regional anaesthesia, it has been described that its use is not associated with neurological decline. In this patient, we decided to use a sequential combined spinal-epidural technique with low-dose spinal anaesthesia in order to induce little haemodynamic changes without exacerbating respiratory function, and ensuring adequate block level by means of the epidural catheter.

The regional technique also offers the possibility of administering epidural morphine for adequate post-operative analgesia and few adverse effects when compared to systemic administration.

Whatever the anaesthetic technique, it is important to consider the high risk of development of deep vein thrombosis in these patients, with the ensuing complication of pulmonary thromboembolism due to factors such as prolonged immobilisation, gestation, and the surgical procedure itself. Consequently, consideration must be given to the use of both pharmacological as well as non-pharmacological thromboprophylaxis measures.

Conclusions

Sequential combined spinal-epidural anaesthesia (CSE) was shown to be a safe anaesthetic technique for caesarean section in this patient with ALS. It provided adequate sensoryand motor block for the surgery with minimum haemodynamic changes and no exacerbation of the respiratory insufficiency present in this patient. It allowed for rapid recovery and adequate post-operative pain management.

Ethical disclosures

Protection of human and animal subjects. The authors declare that no experiments were conducted in humans or animals for this research.

Confidentiality of data. The authors declare having followed the protocols of their institution regarding disclosure of patient information.

Right to privacy and informed consent. The authors obtained the informed consent from the patient and/or subjects mentioned in this article. The informed consent form is available form the corresponding author.