Syringomyelia is the progressive formation of an enlarged, intramedullary cavity (syrinx) filled with cerebrospinal fluid (CSF). There have been six reported cases of pregnancy and syringomyelia, but in none was there any associated neuropathic pain. We report the anaesthetic procedure for the management of a Caesarean section in a patient suffering from both syringomyelia and neuropathic pain.
A 35-yr-old woman with syringomyelia was scheduled to undergo an elective Caesarean section. Her previous history included the fusion of cervical vertebrae (Klippel-Feil syndrome) and a cervical abscess, due to relapsing otitis 7 yr before, had caused arachnoiditis and, subsequently, syringomyelia. Magnetic resonance imaging showed congenital fusion of cervical vertebrae (C4-C6), and a cavity extending from C4 to the conus medullaris. Due to the progressive nature of the disease, she had required eight operations (decompressive laminectomy, syringoscopy and syringostomy), the last one being for syringopleural shunting. At the time of admission for Caesarean section the patient was unable to lie supine because of disabling back pain, kyphoscoliosis (but with no ventilation-perfusion abnormalities) spasticity, allodynia and hyposthesia in the lower extremities. She also suffered from urinary incontinence, abolition of aquilean and patellar reflexes, and absence of propioceptive sensitivity. She was given baclofen orally 75 mg day−1, gabapentin 1200 mg day−1 in three separate doses and diazepam 10 mg day−1. Treatment was maintained over the course of the pregnancy until the Caesarean section due to severity of symptoms.
Monitoring in the operating room was by electrocardiography, pulse oximetry, capnography, noninvasive automated arterial pressure, neuromuscular blockade monitoring, and bispectral index (BIS). A 16-G peripheral intravenous cannula was inserted. A modified rapid sequence induction was performed using remifentanil 0.05 μg kg−1, propofol 180 mg and rocuronium 40 mg. The patient's trachea was intubated with no difficulty. Anaesthesia was maintained with a propofol infusion (9 mg kg−1 h−1); O2: N2O and a remifentanil infusion (0.05 μg kg−1 min−1) until surgical incision. Anaesthesia and surgery proceeded uneventfully and a live female infant was delivered and made spontaneous respiratory efforts within 30 s; Apgar scores were 6 at 1 min and 8 at 5 min. After delivery, the remifentanil infusion was reinitiated (0.5 μg kg−1 min−1), and analgesia was reinforced with 150 μg of fentanyl. Normoventilation was maintained throughout anaesthesia, peak airway pressure was <18 cm H2O and haemodynamic variables remained stable. The trachea was extubated after the administration of atropine 1 mg and neostigmine 2 mg to antagonize residual neuromuscular block. Arousal of the patient after general anaesthesia and subsequent recovery was satisfactory - her neurological status remained unchanged and no postoperative neurological changes were observed. She was discharged on 7th day after the operation.
Syringomyelia is an uncommon chronic progressive degenerative disease, with a prevalence of 8.4 per 100 000, and is characterized by the presence of an expanding, longitudinal cystic cavity within the spinal cord . Sufferers develop a distinctive progressive dysfunction over many years. The clinical manifestation is most often pain originating at the site of the syrinx radiating to neck and upper extremities. Signs and symptoms may include asymmetric loss of pain and temperature in the upper limbs with preservation of touch and position sensation, hyporeflexia, muscular atrophy and spasticity. Weakness in the paraspinal muscles leads to thoracic scoliosis and if there are significant attendant spinal deformities, pulmonary functions can be compromised. Autonomic neuropathy is more likely when syringobulbia coexists, but this was not the case in our patient. Due to muscle denervation, these patients may be at risk of severe hyperkalaemia with succinylcholine. Despite initial resistance to non-depolarizing agents, such patients may demonstrate prolonged neuromuscular weakness as a result of decreased muscle strength and mass. We used rocuronium at induction because it permits fast tracheal intubation and avoids the use of succinylcholine. Our patient responded normally to non-depolarizing agents. In such patients, there is high risk of spinal cord damage and sudden clinical deterioration after coughing and vomiting, so any increase in intracranial pressure must be avoided. Remifentanil is an ultra short-acting receptor agonist with an analgesic potency similar to that of fentanyl. We use remifentanil as part of a general anaesthetic technique to avoid a significant response to endotracheal intubation and to provide stable cardiovascular parameters. The rapid offset of remifentanil would eliminate the potential prolonged respiratory depressant and sedative effects on the mother or neonate [2,3]. For increased safety, the perfusion of remifentanil was suspended at the moment of incision in order to favour fetal metabolism of the drug and avoid possible neonatal respiratory depression; significant respiratory depression in the neonate did not occur. The perfusion of remifentanil was reinitiated after the birth until the end of the operation and anaesthetic depth was monitored closely throughout using a BIS monitor.
Our patient did not show any increased intracranial pressure and normoventilation was maintained during anaesthesia to avoid interactions between controlled mechanical ventilation and the syringopleural shunt. High peak airway pressures were also avoided.
The implications of anaesthetics given to patients with neuropathic pain are related to the medication maintained throughout the term of the pregnancy. General anaesthetics can cause central nervous system (CNS) depression owing to effects on supraspinal receptors, which may be exacerbated by other CNS depressants such as general anaesthetics; they can potentiate opioid-induced analgesia, and may also disturb the autonomic circulation control, including haemodynamic complications, such as severe bradycardia and hypertension . The perfusion of remifentanil allowed us to maintain a close control over the haemodynamic condition of the patient throughout the procedure. Anaesthesia, surgery and recovery were all uneventful.
Great care should be taken with the chosen anaesthetic. It is vital to prevent any rise in CSF pressure. During epidural anaesthesia, although cerebrospinal pressure is maintained there is a risk of dural puncture, and the potential onset of symptoms afterwards - thus spinal anaesthesia is best avoided. Respiration function is less compromised during epidural anaesthesia than during general anaesthesia and the potential hazards of securing the airway are avoided [5-7]. We discarded epidural anaesthesia because of the many operations our patient had previously undergone and because of the risk of dural puncture - in any case the patient must be informed of the risks involved in any of these techniques. Patients with syringomyelia require close postoperative observation because sudden apnoea or cardiac arrest may occur due to the associated autonomic neuropathy.
F. J. Palacio
Department of Obstetric Anaesthesiology; La Paz University Hospital; Madrid, Spain
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