Introduction
The development of tropical myeloneuropathies, such as tropical ataxic neuropathy (TAN) and Konzo has been linked to cassava toxicity. The progressive onset of ataxia is a hallmark of TAN, a myeloneuropathy initially identified in Nigeria. On the other hand, Konzo is a chronic, clinically different, sudden-onset disease of the upper motor neurons first identified in the Democratic Republic of the Congo (DRC).
The Yaka tribe in the DRC gave the word "Konzo," which means tied legs, to describe a fetish used by hunters to weaken legs and trap wild animals. According to the literature, Konzo has been well-known to the Yaka natives of the Bandundu province in Zare, now known as the DRC, since the end of the 19th century.
However, the syndrome was not first mentioned in the medical literature until many years later. Several other sub-Saharan African nations, including Mozambique, Tanzania, the Central African Republic (CAR), Cameroon, Angola, and most recently, Zambia, have since recorded Konzo outbreaks. While there may be individual incidences of the disease, it typically manifests as an outbreak that is thought to be brought on by emergency events like hunger, civil conflicts, or drought.
Most epidemiological investigations have demonstrated a connection between Konzo outbreaks, agroecological failure, and intake of bitter cassava, a staple food for millions of people in sub-Saharan Africa. Although Konzo can affect both men and women, adult males are less likely to be impacted, and no research has shown that Konzo can affect children under the age of two.
For reasons that have not yet been determined, the disease primarily affects people over three and fertile women. Konzo is thought to have afflicted hundreds of thousands of people overall, with most instances taking place in the DRC. Because of imprecise demographic data and inadequate surveillance systems, it has been challenging to acquire accurate prevalence estimates.
What Are the Neurological and Clinical Features of Konzo?
The laypeople can quickly recognize Konzo within the affected areas due to its unusual start and clinical symptoms. The illness strikes suddenly and is frequently preceded by physical efforts, such as a long walk. Affected individuals report trembling, a feeling of weakness, heaviness, or stiffness in their legs, as well as cramps that are typically limited to the calf muscles during the initial phase of the condition. It is common to have paraesthesia, numbness, muscle aches, and a feeling of electrical discharge in the backs of the legs, among other acute reversible sensorial symptoms. Vision fuzziness and trouble swallowing have occasionally been reported. Clinical impairments are typically more severe at the beginning of the disease, keeping the patients confined to beds.
The disease's course stabilizes after a few days, and the deficiencies are primarily limited to the motor system. A "second attack" is still conceivable, though. The most noticeable characteristic of affected individuals, who may still be able to walk and run, is their cross-legged gait. Once stabilized, a symmetrical postural anomaly with a spastic gait during ambulation is the most obvious symptom. Only when the subject is asked to run among individuals who are only minimally afflicted by the condition does the person's spasticity of the legs become apparent.
The following definition and epidemiological criteria for the condition have been established by the World Health Organization (WHO): a high reliance on cassava as a staple meal, an abrupt start of leg weakness, and a non-progressive course of the disease in a previously healthy person. Exaggerated knee or ankle jerks on both sides when walking or running without any indication of a spinal condition.
The primary clinical picture of Konzo at the neurological examination is an isolated symmetric spastic paraparesis. When examined in the recumbent position, deep tendon reflexes of the lower limbs are accentuated, and extensor plantar responses are typically visible. In seriously affected individuals, the ankle clonus and abnormal reflexes of the upper extremities are usually discovered, together with an obvious palm omental reflex.
Those severely affected may have tetraparesis, trunk weakness, and pseudobulbar indications like difficulty speaking and swallowing. Konzo patients may also exhibit bilateral optic neuropathy. Visual impairment, temporal pallor of the optical discs, and visual field deficiency are all included in this disorder.
In a few instances, a pendular nystagmus has been noted. The severity of Konzo does not appear to be connected with the occurrence of visual symptoms at the disease's beginning or optic neuropathy during future exams. Urinary, digestive, and sexual functions also seem clinically normal, as do hearing and sensory functions.
What Is the Treatment Given for Konzo?
There is no known effective treatment for Konzo at this time. The neurological damage is severe and long-lasting. Yet, after the neuroimaging process has stabilized, the impairment remains intact and cannot be reversed, even in severely damaged individuals who utilize walking assistance.
Reconstructive surgery and physical therapy have been used to lessen muscle spasms and contractures. A few patients in the Central African Republic have shown success following proximal tendon release of the calf. These patients could stand upright once more, improving their gait and standing. Try centrally-acting spasmolytics or intramuscular botulinum toxin injections, successfully used to lessen adductor spasticity in cerebral palsy patients. However, no such therapeutic studies have yet been conducted on Konzo patients.
The agricultural, educational, and public health capacity and infrastructure required to implement dietary changes present challenges to Konzo-affected regions. These areas are unable to diversify their essential foods for the same reasons. Right now, prevention is the key to getting rid of Konzo.
Konzo causes neurological damage, and there is no known treatment, so the fight against the illness must concentrate on prevention. An effective way to lower the amount of cyanogen in cassava was found in 2005 by an Australian expert. In the DRC, the so-called "wetting approach" has been applied successfully to stop Konzo epidemics.
Depending on how hospitable the environment is, Konzo victims can live with their disability for decades. As a result, it will be feasible to record a "post-Konzo" syndrome in elderly individuals, which manifests as increasing pain and weakness brought on by contractures and joint malalignment. Although switching from bitter to sweet cassava, which is less toxic, has been suggested, it is not the best option because only bitter cassava can grow in the area due to the soil's acidity.
Conclusion
The human model of cyanide poisoning from food (cassava) presents priceless chances to investigate therapeutic possibilities, such as antidotes for cyanide poisoning, and understand the neuropathogenic mechanisms underlying the long-term effects of cyanide exposure on the brain. Testing and validation of point-of-care diagnostic instruments to assess and monitor levels of cyanide exposure and metabolites in relation to risks for neurological illnesses and child neurodevelopment are further prospects that should be investigated.
