Hashimoto's Encephalopathy - SREAT

SREAT -- Steroid-Responsive Encephalopathy Associated w/ Autoimmune Thyroiditis

Scanning of a thyroid
Hashimoto's Disease. Enrico Fianchini / Getty Images

The disease known as "Hashimoto's Encephalopathy" was first described only in 1966. After that time, doctors began to assemble case reports, and "Hashimoto's Encephalopathy" became the accepted name for the condition of encephalopathy associated with Hashimoto's thyroiditis.

Because most patients with Hashimoto's Encephalopathy improve with steroids or immunosuppressant treatment, some experts now refer to the condition as "steroid-responsive encephalopathy associated with autoimmune thyroiditis" (SREAT).

In some cases, the condition may also be called "nonvasculitic autoimmune meningoencephalitis​" (NAIM), which can include not only autoimmune thyroid problems but also other autoimmune disorders such as Sjögren syndrome and systemic lupus erythematosus–associated meningoencephalitis. The commonality among all these conditions is that they respond to steroid treatment.

The term "encephalopathy" refers to a disease of the brain that alters brain function or structure. The key feature of any encephalopathy is altered mental state. While symptoms depend on the type of encephalopathy and how serious it is, some common symptoms include:

  • memory loss
  • difficulty concentrating
  • loss of cognitive ability and function
  • personality changes
  • lethargy and fatigue
  • loss of consciousness
  • myoclonus (an involuntary twitching of muscles)
  • nystagmus (rapid, involuntary eye movement)
  • tremors
  • weakening of muscles
  • dementia
  • seizures, convulsions
  • difficulty swallowing
  • difficulty speaking

Some other symptoms that may be seen include:

  • confusion, disorientation
  • psychosis
  • headaches
  • right sided hemiparesis - right sided partial paralysis
  • fine motor movement problems - problems with coordination of arms, hands, fingers

Because Hashimoto's Encephalopathy/SREAT is so misunderstood, in a study reported on in the February 2006 Archives of Neurology, experts set out to characterize the various clinical, laboratory, and radiologic findings of the condition.

Their objective is to help improve doctors' ability to recognize and diagnose this condition.

The study looked at 20 patients (14 women, 6 men) who were diagnosed between 1995 and 2003. Their median age at disease onset was 56 years, with a range of 27 to 84 years (range, 27-84 years).

The most frequent observable clinical features/symptoms were:

  • Tremor -- 80%
  • Transient aphasia -- 80% ( Aphasia is difficulty with language, affecting the ability to speak, read or write)
  • Myoclonus -- 65% (sudden, involuntary jerking of a muscle or group of muscles )
  • Gait ataxia -- 65% (uncoordinated or clumsy walking, difficulty walking)
  • Seizures -- 60%
  • Sleep abnormalities -- 55%

Misdiagnosis is Standard

What is of particular concern is that the experts found that ALL PATIENTS had originally been misdiagnosed. For example:

  • Viral encephalitis -- 25%,
  • Degenerative dementia -- 20%
  • Creutzfeldt-Jakob disease -- 15% (Creutzfeldt-Jakob disease is a rare, degenerative, invariably fatal brain disorder, sometimes erroneously referred to as "Mad Cow Disease" in humans)

    Laboratory and Test Abnormalities in Hashimoto's Encephalopathy/SREAT

    A number of test abnormalities were observed, including:

    • Increased liver enzyme levels -- 55%
    • Increased thyroid-stimulating hormone (TSH) levels -- 55%
    • Increased erythrocyte sedimentation rate ("sed rate") -- 25%
    • Cerebrospinal fluid abnormalities suggesting inflammation -- 25%
    • Magnetic resonance imaging abnormalities consistent with encephalopathy -- 26%

    Conclusions

    The researchers concluded that there are a variety of findings that can be associated with Hashimoto's Encephalopathy/SREAT, and that misdiagnosis is common.

    The researchers recommend that Hashimoto's Encephalopathy/SREAT should be considered even if TSH and "sed rate" are normal, cerebrospinal fluid does not show evidence of inflammation and the MRI is normal.

    Sources

    Castillo, Pablo MD; et. al. "Steroid-Responsive Encephalopathy Associated With Autoimmune Thyroiditis." Arch Neurol. 2006;63:197-202. (Vol. 63 No. 2, February 2006)

    National Institute of Neurological Disorders and Stroke

    For More Information

    Hashimoto's Encephalopathy Information Page

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