A 24-year-old man complained of instability of his feet since the age of 16 years. From the age of 19 years onwards, he could no longer stand on tiptoe, and he experienced difficulties when playing basketball. At 20 years of age, his calves appeared to be thin. Gradually, he had some difficulty running, whereas he could climb the stairs and rise from a chair normally. He had no symptoms in his arms. The parents did not have similar problems.

A 76-year-old man was referred with a diagnosis of ‘motor neuron disease’ or ‘polyneuropathy’. For about eight months he had noticed progressive muscle weakness in his right leg associated with pain, initially more intense than at referral, and a numb feeling around the right knee. Two years previously his left hand had become weak and wasted, associated with loss of sensation of the ring finger, the little finger, and the ulnar part of the palm of his hand. He had lost weight (5 kg) unintentionally over the past six months. He had always been very active, but was now no longer able to walk his dog or do some gardening. He was recently diagnosed with diabetes mellitus (DM) for which oral antidiabetics were prescribed. Family history was unremarkable.

Within a period of a few days, a 34-year-old woman developed progressive weakness of the right leg without pain. Having suffered spontaneous bone fractures as a child, she had been diagnosed with insensitivity to pain syndrome. She had never been able to perspire; this meant warm weather was not well tolerated and it resulted in an increase in body temperature. The tip of the right thumb had been amputated following a skin ulcer (‘panaritium’).

Electrodiagnostic studies are often at the centre of diagnostic strategies in neuromuscular disorders. The basic electrophysiological techniques commonly used are focused on documenting sufficient proof of dysfunction emanating from different parts of the peripheral nervous system: peripheral motor neuron, nerve root, plexus and peripheral nerve, neuromuscular junction, and skeletal muscle. In short, dedicated nerve conduction studies and needle myography or a combination of these may be needed to help accurately identify the site and nature of the neuromuscular disorder (Fig. 4.1A–C). Appropriate and standardized instrumentation, including control of temperature and uniform sampling, is essential for meaningful interpretation. The electrodiagnostic techniques aligned with the main anatomical correlates underlying different neuromuscular disorders are discussed in this chapter.

A 70-year-old man noticed a feeling of walking on cotton wool for the past two years. Numbness had progressed from the toes to the knees, and for half a year there was tingling and numbness in the fingertips. These complaints were symmetric and there was no pain. Walking had become insecure. For one year he had no erections, whereas sexual function had previously been normal. There were no other signs of autonomic dysfunction. In the past two years there was also shortness of breath on exertion. A diagnosis of cardiomyopathy had been made recently.

The family history revealed vitreous opacities in the father and several siblings. A brother also had sensory disturbances in his feet and a thickened heart muscle. His four daughters did not have any complaints.

Since early childhood, a 22-year-old-man had difficulty keeping up with his peers at gym class activities. He noticed increasing weakness in his leg muscles when getting up the stairs, and gradually his arm muscles were also involved. He had noticed rolling movements of his thigh muscles triggered by exercise and squeezing the muscles.

Family history was positive: his brother, mother, maternal grandfather, maternal aunt, and nephew had similar complaints.

A 60-year-old woman was referred because from the age of 50 years onwards she experienced muscle weakness that led to increasing difficulty in climbing stairs. In addition, she complained about exercise-induced myalgia.

History included cataract surgery at the age of 58 years, and lately, unexpected and unexplained falls. Family history revealed early-onset cataract in several paternal family members. Her father and brother had died suddenly and unexpectedly despite a pacemaker.

Magnetic resonance imaging (MRI) and ultrasound (US) of nerves and muscles are increasingly used as complementary tools in the diagnosis of neuromuscular disorders. Ultrasound has superior image resolution over MRI, a flexible field of view, and relatively low cost. US is also the preferred imaging modality when evaluating superficial structures. In contrast, MRI has the advantage of dedicated sequences with unique tissue-discriminating properties, and coverage of more deeply located structures. However, MRI requires dedicated protocols and visual assessment is limited by a high interobserver variability. US is device- and operator-dependent, and less suitable for evaluating much deeper structures. Visual assessment is, like MRI, subject to interobserver variability. Qualitative US has the ability to obtain more objective and repeatable measures.

Note that these listings are not exhaustive. Abbreviations: AD: autosomal dominant; AR: Autosomal recessive; genes in italic.

The main aim of a first consultation will concentrate on establishing a diagnosis. However, there are two other major aims: capturing the expectations of the patient and appreciating the impact of the complaints on daily life.

A 58-year-old previously healthy man had complaints of fluctuating drooping eyelids and weakness of neck extensors, arms, and legs. He almost continuously experienced double vision. Following a diagnosis of myasthenia gravis and improvement with pyridostigmine, he noticed twitches and spasms of muscles virtually all over his body. This became severe, he did not sleep well, was restless, and almost continuously felt the urge to move and walk around. His wife mentioned that he also behaved differently. Initially, a pyridostigmine intoxication was considered, but lowering the dose did not help. Additionally, some autonomic features (constipation, erectile dysfunction) appeared.

When playing slow passages, a 55-year-old professional accordionist noticed painless cramping of the right finger flexors. Treatment with botulinum toxin for suspected dystonia had no effect. In the following months, cramps also occurred at rest, and he had to give up his profession. He also noted twitches in the limb muscles.

An 18-year-old man had noticed progressive painless weakness and a decrease in size of his left forearm and hand for about one year. He was not able to lift objects, and at the gym he had difficulty handling the dumbbells. He had noticed involuntary contractions not only of his forearm muscles, but also of his chest and once in his legs. Previous medical history and family history were unremarkable.

A 35-year-old man complained about muscle stiffness and weakness, especially when initiating a movement. He had experienced these symptoms for as long as he could remember. They were present in his eyes, jaws, tongue, and limb muscles. He had noticed that cold weather had a negative influence. He was not able to run and did not participate in team sport activities. In spite of these symptoms, he experienced no limitations in activities of daily living. He was referred because he had been informed elsewhere about possible treatment. The family history revealed similar symptoms in a sister and a brother, but not in the parents. His father’s grandparents were cousins.

A 27-year-old woman consulted the neurology clinic because of progressive muscle weakness in legs and arms. She noticed increasing difficulty in walking, with a maximum walking time of 15 minutes when there was a slight upwards slope, climbing stairs, and lifting heavy things. She had more and more frequent falls in which it felt like her legs suddenly could not bear her weight anymore. Once she fell, she wasn’t able to get up from the floor without help. At the time of referral, she also experienced problems rising from a sitting position. She also mentioned problems with repeated movements due to fatigability, for example, when she walked or was cleaning out the dishwasher.

In retrospect, she remembered that she had had a ‘typical’ walk from the age of five and had never been able to run. A subtle tremor of her fingers was already present in kindergarten. Her medical history was otherwise unremarkable. She had two healthy siblings.