Kuru Clinical Presentation

Updated: Feb 17, 2016
  • Author: Zartash Zafar Khan, MD, FACP; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Presentation

History

Before kuru had nearly disappeared following cessation of the ritual of endocannibalism, the disease affected only the Fore, a New Guinea highland tribe. Case histories were usually obtained with the aid of a pidgin English–speaking man of the same tribal group as the infected individuals, but, in some cases, a European linguist who spoke the appropriate language was available. Only rarely were infected individuals able to communicate in pidgin English. [27] Kuru has not been reported outside this context. Therefore, the potential for any practitioner encountering a case of kuru in the current era is extremely remote.

Kuru is a cerebellar syndrome with a characteristic and relentless progression of neurological symptoms through well-defined clinical stages. Kuru is invariably fatal. Initially, cognition is fairly well-preserved, and the disease presentation is sufficiently distinctive to be easily recognized by patients, their relatives, and the local community. [13] The initial clinical presentation includes a prodrome of headache and arthralgia followed by the following clinical features: [27, 28]

  • Cerebellar ataxia

  • Voluntary tremor

  • Involuntary movements (choreoathetosis, myoclonic jerks, fasciculations)

  • Euphoria, dementia, emotional liability, and a loss of grasp reflexes in advanced stages

Upon disease progression, infected individuals become sedentary and develop sensory and motor and cranial nerve deficits that lead to progressive wasting, malnutrition, and intercurrent pneumonia. Death typically follows a clinical course of 4 months to 2 years, with most patients dying within a year of symptom onset.

Compared with other prion diseases, kuru’s clinical features most closely resemble those of vCJD. Clinical symptoms of vCJD consist of behavioral, psychiatric, and peripheral sensory disturbances and cerebellar ataxia. Common early psychiatric features include depression, withdrawal, anxiety, insomnia, and apathy. [2] The symptoms of iatrogenic CJD are similar to those of sporadic CJD, which include a prodrome of malaise, headache, and ill-defined pain. Other symptoms include cognitive deterioration, myoclonus, extrapyramidal signs, cerebellar ataxia, pyramidal signs, and cortical blindness. The median age of onset for sporadic CJD is 45-75 years, whereas the median age of onset for vCJD is 26 years. [2]

Among the group of inherited prion diseases, GSS typically presents as a chronic cerebellar ataxia with pyramidal features, with dementia occurring much later. The clinical course is typically longer than that of classic CJD.

FFI is characterized by progressive untreatable insomnia, dysautonomia and dementia, and selective thalamic degeneration. [29, 2]

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Physical

Physical findings during the initial course of kuru are characterized by ataxia and muscular weakness. This results in tremulous legs and walking difficulties that eventually necessitate dependence on sticks, crutches, or human assistance for locomotion. Slow and clumsy movements can lead to injuries sustained by falls. [27]

In the later stages, signs of psychiatric disturbances develop, including loss of emotion control, depression, euphoria, agitation, and confusion. Dementia can also occur in individuals with kuru, but it is a relatively more common feature of CJD. [27, 2]

Neurological signs of kuru include hyperreflexia, loss of grasp reflex, strabismus, and nystagmus. Involuntary muscle jerking and twitching is observed, along with other cerebellar signs such as tremor on finger-to-nose testing, difficulty with heel-to-toe walking, and dysdiadochokinesis. Plantar responses include flexor, and hypotonia is often present in advanced cases. [27, 20]

Ptosis and oculomotor imbalance are observed in a small number of cases. [27]

Eventually, individuals with kuru become bedridden and may even be unable to sit, raise their head, or roll over. In advanced stages, patients lose the ability to chew, swallow, or control excretory processes and become progressively wasted. [20]

Death results from starvation, complicating pneumonia, [28] or infected decubitus ulcers.

The signs and symptoms of vCJD commonly include disorientation, hallucinations, paranoid ideation, confabulation, impaired self-care, and multiple neurological features (eg, cerebellar signs, chorea, dystonia, myoclonus, upper motor neuron signs, visual symptoms). Classic sporadic CJD presents as a rapidly progressive multifocal dementia with myoclonus. Clinical progression to akinetic mutism occurs fairly rapidly, with a median illness duration of only 5 months. Extrapyramidal signs, cerebellar ataxia, pyramidal signs, and cortical blindness are also observed in sporadic CJD. [2] GSS typically presents as a chronic cerebellar ataxia with pyramidal features, with dementia occurring much later in the clinical course than is typically seen in classic CJD. Fatal familial insomnia (FFI) is characterized by progressive untreatable insomnia, dysautonomia and dementia, and thalamic degeneration. [2]

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Causes

Kuru is a prion disease transmitted by endocannibalism. There is no evidence for spread in utero or via human milk. [13, 30]

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