The onset of konzo is sudden, without prodromata. Often a long walk or hard work seems to trigger the onset. The initial symptoms are described as trembling or 'cramping' in the legs, heaviness or weakness of the legs, a tendency to fall or an inability to stand. Symptoms such as low back pain and paresthesia in the legs are occasionally present at the onset but resolve within the first month. During the first few days, most patients experience generalized weakness and are usually bedridden for some days or even weeks before trying to walk.
Spasticity is present from the first day, without any initial phase of flaccidity.
After the initial weeks of functional improvement, the spastic paraparesis remains stable for the rest of life, as confirmed by follow-up studies years and decades after onset. The exception is that some of the patients may suffer an abrupt, aggravating episode, e.g. a sudden and permanent worsening of the spastic paraparesis. The character of such an episode is identical with the initial onset and can therefore be interpreted as a 'second onset'. On clinical examination the most noticeable finding is the isolated symmetric spastic paraparesis, without other neurological symptoms, figure 2. The reflexes of the lower limbs are exaggerated in all cases and extensor plantar responses can be elicited in most cases if done with the patient in recumbent position.