Mrs Downs is experiencing weakness, fatigue, difficulty focusing, drooping eyelids, and weak neck and shoulder muscles. Her doctor diagnoses her with myasthenia gravis based on her symptoms. Myasthenia gravis is an autoimmune disorder where antibodies block signal transmission at the neuromuscular junction. The underlying pathophysiology is that antibodies interfere with acetylcholine receptor function at the neuromuscular junction. The doctor prescribes neostigmine, an acetylcholinesterase inhibitor, to increase acetylcholine levels at synapses and atropine to reduce side effects from excess acetylcholine.

1. 22 CH 2 NEUROLOGICAL DISORDERS
CASE STUDY 12 Drooping eyelids
Learning outcomes
On completion of the following case study, you will be able to:
• describe the synapse and the classification of synapses;
• describe the processes involved in synaptic transmission at the neuromus-
cular junction;
• explain myasthenia gravis and its associated symptoms;
• describe causes which lead to the disease;
• outline pharmacological approaches to managing the symptoms.
Part 1
Mrs Downs has been to see her doctor complaining that she has been feeling weak
lately and becomes tired very easily. She has also noticed that she has a problem
focusing on objects and that her upper eyelids are drooping (this seems worse
when she looks upwards). She feels that the muscles in her neck and shoulders are
becoming very weak and she has difficulty in carrying heavy shopping. The doctor
concludes that Mrs Downs has a neurological problem, makes her diagnosis and
prescribes neostigmine plus atropine.
Q1 What is the likely diagnosis of Mrs Downs’ symptoms?
Q2 What is myasthenia gravis?
Q3 Comment on the underlying pathophysiology of myasthenia gravis.
Q4 Are Mrs Downs’ symptoms consistent with the profile of myasthenia gravis?
Explain your answer.
Q5 What is a synapse?
Q6 How many types of synapse exist in the body?
Q7 Describe the events which occur at the synapse leading to the release of a
neurotransmitter from the nerve terminal.

2. CASE STUDY 12 DROOPING EYELIDS 23
Q8 Do the number of synapses change with age?
Q9 To which category of drugs does neostigmine belong? Your answer should
include its mechanism of action.
Q10 What is the rationale for using atropine in combination with neostigmine?
Part 2
After a few weeks, Mrs Downs went back to her doctor, complaining that her
medication was not very effective.
Q11 Suggest another drug suitable for Mrs Downs.