|LETTERS TO EDITOR
|Year : 2015 | Volume
| Issue : 3 | Page : 197-198
Myasthenia gravis: A challenge
Department of Anaesthesia, Regional Cancer Centre, Medical College PO, Trivandrum, Kerala, India
|Date of Web Publication||12-Mar-2015|
Department of Anaesthesia, Regional Cancer Centre, Medical College PO, Trivandrum 695 011, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Ramesh B. Myasthenia gravis: A challenge. Indian J Anaesth 2015;59:197-8
Most reports of patients with myasthenia gravis undergoing surgery are for thymectomy which is a treatment option in patients unresponsive to medical management.  There are few reports of patients with myasthenia posted for incidental surgery. We would like to report one such case where the patient was scheduled to undergo a modified radical mastectomy for carcinoma of the breast.
A 40-year-old female (50 kg) diagnosed as a case of myasthenia gravis Grade II B since 1 year was scheduled for a mastectomy procedure. She had developed symptoms of dysphagia and dysarthria one year before. On further evaluation, it was diagnosed as myasthenia. She was started on pyridostigmine and steroid (since she did not improve only with pyridostigmine), to which she responded. She was also diabetic (due to steroid therapy) controlled on insulin. Her blood and other investigations were within normal range. Her pulmonary function tests (PFT) showed a decrease in vital capacity (2 L). Other parameters were normal.
Since she was at risk of post-operative respiratory complications  , we decided to avoid general anaesthesia. Among the various options paravertebral block (PVB),  thoracic epidural  block, and tumescent anaesthesia  (block) were considered. Tumescent anaesthesia involves the use of large volumes of local anaesthetic drugs, and was hence avoided. Thoracic epidural block , with a higher concentration of local anaesthetic may produce motor blockade and decrease vital capacity, forced expiratory volume and total lung capacity which was potentially dangerous in our patient due to bulbar muscle involvement. Hence, a PVB was decided to be administered.
After patient consent and premedication with midazolam (1 mg) and fentanyl (70 μg) , PVB was performed between T1 to T6 levels. 4cc of 0.25% bupivacaine with adrenaline was injected at each space. Sensory block was assessed over the respective dermatomes, and the surgery was continued with top ups of sedation and opioid analgesia (fentanyl 30 μg and dexmedetomidine 20 μg). Propofol (50 mg) was administered during the axillary clearance. Surgery lasted 90 min. The patient remained comfortable during the procedure. Analgesia lasted for 6 h post-operatively. She was restarted on oral dose of pyridostigmine soon after the procedure. She was discharged on the 3 rd post-operative day.
In patients with myasthenia, the parameters which indicate the need for post-operative mechanical ventilation include disease duration , >6 years, associated lung disease, pyridostigmine dose requirement >750 mg/day and vital capacity <2.9 L. Hence, a pre-operative lung function assessment is of utmost importance. Since the patient had dysphagia, possibility of aspiration is higher. A previous meta-analysis performed showed that PVB combined with general anaesthesia provided better post-operative analgesia , during breast surgery. Lesser incidence of adverse effects was reported with the use of PVB. , Since acute post-operative pain is a risk factor for the development of post-operative chronic pain , , use of PVB is useful. PVB has also been shown to provide better analgesia than wound infiltration. PVB also provides better post-operative dynamic analgesia. Single level and catheter technique have been described, but we used the multiple injection technique.
We conclude that regional anaesthesia, especially PVB is a feasible alternative in patients with myasthenia gravis undergoing modified radical mastectomy.
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