A 60-year-old man reported slowly progressive symptoms over a period of five years. He experienced tingling in his toes that gradually spread halfway up the lower legs. He also developed a stiff feeling in his lower legs and nightly cramps in both calves, but no pain. For one year, he complained of numb fingertips with some loss of dexterity. He had no symptoms of autonomic dysfunction, was not known to have diabetes, ate a healthy, balanced diet, drank one glass of alcohol a day, and had not been treated with neurotoxic medication. His family history indicated no other relatives with similar complaints.

A 40-year-old man was referred because he wished to be informed about the genetic nature of his disorder. He was diagnosed with Charcot–Marie–Tooth (CMT) disease. At 14 months of age, he started walking, but awkwardly due to a bilateral drop foot for which braces were prescribed. On first examination at age 2 years and 8 months, there was marked atrophy, hypotonia, and areflexia of the lower legs, and slight wasting of the thenar and hypothenar. At that time, nerve conduction studies showed normal motor conduction velocities of arm nerves. No motor unit action potentials could be recorded in the lower leg muscles on concentric needle examination.

A 48-year-old man had complained about the painful soles of his feet for several months. This pain was present constantly but increased on touch and when walking. He was a marathon runner but could no longer train or walk properly because of the pain. He did not report weakness, sensory disturbances, discoloration of his feet, or swelling of his joints. Otherwise, he was healthy. He was not known to have diabetes mellitus or any other chronic disorder, such as sarcoidosis, which can cause a painful neuropathy. There were no cardiovascular or intestinal complaints, and no symptoms of autonomic dysfunction. Symptoms that could suggest malignancy were absent. He did not use any medication, had not been treated with any neurotoxic drug earlier, did not smoke, and drank only very limited amounts of alcohol. There was no family history of neurological disorders.

A 73-year-old-woman noticed pain in her right lower leg and thigh and left foot. After a few weeks of physiotherapy, she gradually developed tingling in her feet and a ‘plastic’ sensation in the soles of her feet. A few weeks later, her feet became completely numb, and she noticed painful tingling in her hands and around her left knee. Because of the tingling in her hands, she could barely use a fork and knife. Walking became difficult due to the dull feelings in her legs. Several drugs against painful neuropathy did not help. For years she had smoked two packs of cigarettes a week. A total of 50 pack-years was estimated.

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 24-year-old woman had difficulty with walking since early childhood. At age 18 months she was able to walk without support. She often stumbled and could not keep up with her peers in gym class. However, she still had been able to walk 5 km during a four-day walking event. Management included physiotherapy, and she had orthopaedic shoes. She underwent surgery at age eight years (tendon repositions of both feet). Family history was not available because she was adopted. Previous history includes bilateral congenital hip dysplasia and congenital hypothyroidism.

This chapter summarizes the explanations developed in preceding chapters, fits them into a more comprehensive theoretical framework, and tests them using path analysis, which helps researchers understand causal sequences. Democratization is characterized by punctuated equilibrium. Distant historical factors such as geography and demographic characteristics, together with incrementally changing aspects of social and economic development, affect a country’s level of democracy, but only roughly. Institutions and organizations such as a healthy civil society, the rule of law, and institutionalized political parties, tend to reinforce one another and keep each country’s level of electoral democracy close to an equilibrium or set point. However, short-term economic performance, anti-system movements, and opposition campaigns can sometimes disturb the equilibrium, making significant upturns and downturns possible.