Nodding Syndrome

Nodding syndrome, nodding disease
Some children with nodding syndrome are tied up by their
parents in order to keep them safe. Many are disoriented,
confused and can fall while nodding.
Nodding syndrome is a neurological condition with unknown cause. It was first documented in the United Republic of Tanzania in the 1960s, then later in the Republic of South Sudan in the 1990s and in northern Uganda in 2007. Typically, nodding syndrome affects children between the ages of 5 and 15 years old, but cases have been reported in children as young as 2 years old and in adults up to 32 years old. There is no observed significant difference in the proportion of males to females among the affected, nor is there an observed seasonal variation. The syndrome causes progressive cognitive dysfunction, neurological deterioration, stunted growth and a characteristic nodding of the head. 
 
To date, nodding syndrome is known to occur in the southern region of the United Republic of Tanzania (Mahenge mountains, Ulanga District), South Sudan (Western Equatoria State, Eastern Equatoria State, Central Equatoria State, and Lakes State) and northern Uganda (Pader, Kitgum and Lamwo districts, with new cases starting to present in Gulu, Amuru, Oyam and Lira districts).

Symptoms

Children affected by nodding disease experience a complete and permanent stunting of growth. The growth of the brain is also stunted, leading to mental handicap. The disease is named for the characteristic, pathological nodding seizure, which often begins when the children begin to eat, or sometimes when they feel cold. These seizures are brief and halt after the children stop eating or when they feel warm again. Seizures in nodding disease span a wide range of severity.
 
Researchers have stated that upon presentation with food, "one or two [children] will start nodding very rapidly in a continuous, pendulous nod. A nearby child may suddenly go into a tonic–clonic seizure, while others will freeze." Severe seizures can cause the child to collapse, leading to further injury. Sub-clinical seizures have been identified in electroencephalograms, and MRI scans have shown brain atrophy and damage to the hippocampus and glia cells.
 
A curious feature is that no seizures occur when victims are given an unfamiliar food; e.g. a candy bar.

Diagnosis and treatment

Diagnosis is not very advanced and is based on the telltale nodding seizures of the victims. When stunted growth and mental handicap are also present, probability of nodding syndrome is high. In the future, neurological scans may also be used in diagnosis. As there is no known cure for the disease, treatment has been directed at symptoms, and has included the use of anticonvulsants such as sodium valproate and phenobarbitol. Anti-malaria drugs have also been administered, to unknown effect.

Possible causes

It is currently not known what causes the disease, but it is believed to be connected to infestations of the parasitic worm Onchocerca volvulus, which is prevalent in all outbreak areas. O. volvulus, a nematode, is carried by the black fly and causes river blindness. In 2004, most children suffering from nodding disease lived close to the Yei River, a hotbed for river blindness, and 93.7% of nodding disease sufferers were found to harbour the parasite - a far higher percentage than in children without the disease. A link between river blindness and normal cases of epilepsy, as well as retarded growth, had been proposed previously, although the evidence for this link is inconclusive.
 
The CDC is investigating a possible connection with wartime chemical exposure. The team is also investigating whether a deficiency in vitamin B6 (pyridoxine) could be a cause, noting the seizures of pyridoxine-dependent epilepsy and this common deficiency in disease sufferers. Older theories include a 2002 toxicology report that postulated a connection with tainted monkey meat, as well as the eating of agricultural seeds provided by relief agencies that were covered in toxic chemicals.

Prognosis

The disease itself is not fatal but children often die by falling into cooking fires, drowning during a seizure, or succumbing to malnutrition related illnesses. Parents also lose patience caring for their disabled children and often abandon them.
 
Below is a video about nodding syndrome made by Global Health Frontline News.