What Is Sporadic Fatal Insomnia?

Sporadic fatal insomnia (sFI) is a disease that attacks the brain and central nervous system, inhibiting their proper functioning, and is marked by muscle spasms, cognitive difficulties, and sleep abnormalities. There is no known cure for sFI, which results in rapid physical degeneration and death. Fortunately, sFI is extremely rare. The source of the disease is the presence of prions, or defective proteins, in the brain. For this reason, medical researchers categorize sFI as a prion disease rather than as a sleep disorder.

Though sporadic fatal insomnia cannot be prevented or cured, it can be treated to ameliorate symptoms and possibly extend the patient’s life. Palliative and hospice care are also available. If you or a loved one is suffering from a potentially life-threatening condition, the medical specialists at Baptist Health are available to help.

What Are Sporadic Fatal Insomnia Symptoms?

The earliest symptoms of sFI typically occur in a patient’s middle age. These include:

• Hypertension
• Weight loss
• Elevated heart rate
• Profuse sweating
• Diplopia (double vision)
• Swings in body temperature

In the later stages of sFI, symptoms become more severe:

• Involuntary muscle movements (ataxia)
• Difficulty swallowing (dysphagia)
• Memory loss
• Hallucinations
• Delirium

Insomnia, or difficulty sleeping, is actually one of the less common symptoms of sFI. That said, sleep-cycle abnormalities often turn up during medical testing.

Though the onset of sFI is slow to occur, its development, once begun, is rapid. Life expectancy for sFI patients is somewhat longer than that for a related disease, familial fatal insomnia (FFI).

What Causes Sporadic Fatal Insomnia?

SFI is caused by prions, or defective proteins, found in the brain. The familial form of fatal insomnia is acquired genetically. This is not the case with the sporadic form, in which the prions change to their defective form seemingly at random, though environmental or other factors are likely involved. These defective prions are sometimes described as “misfolded”. The prion’s misshapen quality undermines the role that the protein normally plays in brain health. Additionally, the misfolded characteristic of the prion may be transmissible to other molecular bodies, though this remains under study. Prions are implicated in a number of serious neurodegenerative diseases in humans and other mammals.

The lifetime buildup of prions in the thalamus is the trigger for sporadic fatal insomnia. The thalamus is a gray-matter structure inside the brain that, among other tasks, helps to regulate consciousness, mental acuity, and the sleep cycle. It is these critical aspects of a person’s existence that are threatened by the accumulation of prions in that part of the brain.

What are the Risk Factors for Sporadic Fatal Insomnia?

Risk factors for sporadic fatal insomnia include:

• Genetic: Fatal familial insomnia has an established genetic source. The relationship between genetics and sFI is less clear. A person with sporadic fatal insomnia will not have inherited the source of the mutated prions from a parent. Rather, the mutation appears to arise spontaneously for reasons as yet unknown. It may be possible for persons with this so-called de novo mutation to pass it on to their children.
• Environmental: Some evidence exists that mutated prions can be transmitted via the environment, for example, in a healthcare facility or through the consumption of meat from an animal that also has a prion disease.

How Is Sporadic Fatal Insomnia Diagnosed?

SFI is marked by the symptoms noted above. Confirmation of diagnosis involves several types of medical testing:

• Cerebrospinal fluid analysis (CSF): This is a test for indicators in brain and spinal column fluid that are associated with various medical conditions, including fatal insomnia.
• Electroencephalogram (EEG): EEGs record patterns of brainwave activity, with an eye to apparent abnormalities.
• Genetic testing: A genetic test can detect the presence of a mutated form of the PRNP gene, which provides the faulty chemical instructions for creating the misfolded prions. The absence of this mutation in persons otherwise manifesting the symptoms of fatal insomnia indicates the sporadic rather than the familial version of the disease.
• Imaging tests: These are non-invasive visual “snapshots” of the brain, such as computed tomography (CT) scans, positron-emission tomography (PET) scans, and magnetic-resonance imaging (MRIs).
• Polysomnography: This is a sleep test, typically conducted overnight in a healthcare setting, with the patient connected to monitors that record physiological change throughout the sleep cycle.

The diagnosing physician may also order labs, including bloodwork and liver-function tests.

How Is Sporadic Fatal Insomnia Treated?

Because there is no cure for sFI, treatment focuses on controlling symptoms and reducing a patient’s discomfort. To that end, the following treatments are utilized:

• Medications for inducing deep sleep, such as phenothiazines and gamma-hydroxybutyrate
• Drugs for controlling muscle spasms, such as clonazepam
• Vitamin therapy, especially B vitamins and iron
• Medication management to decrease or eliminate drug usage in those cases where the prescriptions exacerbate sFI symptoms
• Psychosocial therapies, which emphasize adaptation by patients to current circumstances, with resources and reassurance from a likeminded support community
• Hospice care during the terminal stage of the disease

Research is ongoing for therapies to extend the life of sFI patients. Antibody-based immunotherapies and T-cell injections have yet to prove beneficial.

Can Sporadic Fatal Insomnia be Prevented?

There is, unfortunately, no effective form of prevention for sporadic fatal insomnia. However, it is important to remember that sFI is extremely rare. Only two dozen persons have been diagnosed with sporadic fatal insomnia as recently as 2018.

Learn More About Sporadic Fatal Insomnia at Baptist Health

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