Creutzfeldt Jakob Disease

Creutzfeldt Jakob disease is a rare, invariably fatal, rapidly progressive neurodegenerative disorder. It is caused by accumulation of an abnormal, protease resistant conformational isoform of the normal host prion protein. No curative treatment exists, and management is entirely supportive and palliative.

It is classified into three forms:

• Sporadic: the large majority of cases, arising spontaneously without an identifiable external source.
• Genetic: associated with specific mutations in the prion protein gene, inherited in an autosomal dominant pattern.
• Acquired: variant Creutzfeldt Jakob disease, linked to dietary exposure to bovine spongiform encephalopathy prions, and iatrogenic disease from historical exposure to contaminated human derived pituitary hormone or dural graft material.

Pathophysiology

The normal cellular prion protein converts into an abnormal, misfolded conformation that resists normal proteolytic degradation. This abnormal protein acts as a template to convert further normal protein molecules into the same misfolded form, in a self propagating cascade.

It accumulates within neural tissue and causes characteristic spongiform vacuolation, neuronal loss and gliosis. The immune system is not involved and there is no inflammatory response. This distinguishes the underlying pathological process fundamentally from infectious causes of encephalopathy, despite the transmissible nature of the abnormal protein itself.

Sporadic Creutzfeldt Jakob disease typically presents in patients over sixty years with a rapidly progressive dementia, developing over weeks to a few months. Accompanying features are myoclonus (often startle induced), cerebellar signs (ataxia, dysarthria), visual disturbance and, as the disease progresses, akinetic mutism.

Death typically occurs within a median of four to six months from symptom onset. This rapidity of progression is itself a key distinguishing feature from the far more gradual course typical of the common neurodegenerative dementias.

Variant Creutzfeldt Jakob disease presents differently, typically in younger patients. A longer initial prodrome of psychiatric symptoms (depression, anxiety, withdrawal) and painful sensory symptoms precedes the more characteristic neurological features. The overall disease course is somewhat more protracted than in the sporadic form.

Genetic forms present with a variable clinical picture depending on the specific underlying mutation, sometimes with a more prolonged course. Actively seek a family history of a similar rapidly progressive neurological illness.

Magnetic resonance imaging, particularly diffusion weighted and fluid attenuated inversion recovery sequences, is the most useful non invasive diagnostic investigation. It shows characteristic cortical ribboning (restricted diffusion following the cortical gyral pattern) and basal ganglia signal change. A distinctive posterior thalamic signal change (the pulvinar sign) is described specifically in variant Creutzfeldt Jakob disease.

Cerebrospinal fluid real time quaking induced conversion assay is the most sensitive and specific available biomarker test. It directly detects abnormal prion protein through an in vitro amplification technique.

It has substantially improved diagnostic confidence compared with older, less specific cerebrospinal fluid markers such as 14 3 3 protein and total tau. These remain supportive but non specific findings that can be elevated in other rapidly progressive neurological conditions.

Electroencephalography can show characteristic periodic sharp wave complexes in sporadic disease. This finding is neither universally present nor entirely specific, and is less consistently observed in variant disease.

A full workup to exclude other causes of rapidly progressive dementia is essential before this diagnosis is accepted, given the devastating implications. Several treatable mimics exist:

• Autoimmune and paraneoplastic encephalitis
• Central nervous system vasculitis
• Hashimoto encephalopathy
• Severe metabolic or toxic encephalopathy

Actively consider and exclude all of these through appropriate autoimmune, inflammatory, metabolic and toxicological screening.

Genetic testing for prion protein gene mutations is performed where a genetic form is suspected. Offer appropriate pre and post test genetic counselling, given the significant implications for the patient and family members.

No disease modifying or curative treatment is available for any form of Creutzfeldt Jakob disease. Management is entirely supportive and palliative. It focuses on symptom control and support for the patient and family through a rapidly progressive and universally fatal illness.

Myoclonus can be distressing and disruptive. Manage it symptomatically with clonazepam, starting at a low dose such as 0.5 mg twice daily and titrating according to response and tolerability. Sodium valproate or levetiracetam are alternatives, chosen according to individual patient factors and concurrent medications.

Manage agitation, confusion and behavioural disturbance with the standard supportive and, where necessary, pharmacological approaches used in advanced dementia and delirium. Minimise unnecessary intervention and prioritise comfort as the disease progresses.

Early and proactive involvement of palliative care services is essential, given the rapid, predictable and universally fatal trajectory. Palliative care supports advance care planning discussions, symptom management and end of life care. Offer psychological support to the family, given the profound and rapid nature of the decline they are witnessing.

Strict infection control precautions are required for any surgical or invasive procedure on a patient with suspected or confirmed prion disease. There is a recognised risk of iatrogenic transmission through contaminated surgical instruments. This applies particularly to neurosurgical and ophthalmic procedures involving high infectivity tissue.

Apply specific enhanced decontamination protocols or single use instrument policies according to national prion disease guidance.

Notify the relevant national surveillance unit for prion disease of every suspected or confirmed case. This supports ongoing epidemiological monitoring. Where a specific acquired source is identified or suspected, it supports public health investigation of the potential exposure route.