Hashimoto Encephalopathy: a do–not–miss in the differential diagnosis of dementia

Hashimoto's encephalopathy: Follow-up data from neuropsychology, lumbar puncture, and FDG-PET

Hashimoto's encephalopathy is a rare disease with nonspecific symptoms, associated with elevated levels of anti-TPO and/or anti-TG. It can be potentially fatal. However, it is responsive to steroid and treated in due time, it can be fully reversible.

Initial serum thyroid peroxidase antibodies and long-term outcomes in SREAT

OBJECTIVE

To quantify clinical outcome in patients with steroid-responsive encephalopathy and associated autoimmune thyroiditis (SREAT) after the acute phase and explore potential associations of initial serum thyroid peroxidase antibody titers (TPO-Abs) with outcome.

MATERIALS AND METHODS

Retrospective chart review of patients diagnosed with SREAT between 01/2005 and 05/2014 in a tertiary care center and followed in an affiliated autoimmune outpatient clinic. Outcome was quantified using the extended Glasgow Outcome Scale (GOS-E). We calculated Pearson's correlation coefficients to quantify associations with clinical outcome at follow-up.

RESULTS

Among 134 patients with encephalopathy of unknown etiology, we identified 13 patients diagnosed with SREAT. In two patients, the diagnosis was revised at subsequent hospitalization (NMDA-R encephalitis and adult-onset Still's disease). The median follow-up time was 11 months, and the median GOS-E was 6 (range 3-8). Higher serum TPO-Ab-titers correlated with more favorable outcomes (Pearson coefficient 0.65, P = 0.03).

CONCLUSION

A correlation between TPO-Ab-titers and outcome has not been reported previously and challenges the notion of a mere bystander role of TPO-Abs in SREAT.

Electroencephalography of autoimmune limbic encephalopathy

There is an increasing recognition of autoimmune limbic encephalopathy with the hope for earlier diagnosis and expedited and improved treatment. Although antibody testing remains the definitive clinical diagnostic feature, the presentation of a rapid dementia, behavioral changes, and seizures leads to investigation using cerebral imaging, electroencephalography, and cerebrospinal fluid to confirm the diagnosis and also to exclude similar disorders. The electroencephalographer may be asked to comment on the types of electroencephalography abnormality and provide input toward the diagnosis of limbic encephalopathy. This article reviews the literature on limbic paraneoplastic and nonparaneoplastic encephalopathies, providing descriptions and examples of the electroencephalography findings. Typically, there are patterns of slow theta and delta activity and different patterns of temporal and frontal epileptic activity.

Diagnostic and therapeutic aspects of Hashimoto's encephalopathy

OBJECTIVE

To share our experience on clinical presentation and management of patients diagnosed with Hashimoto's Encephalopathy (HE) at Vanderbilt Medical Center between 1999 and 2012.

BACKGROUND

HE is a rare disorder characterized by encephalopathy and central nervous system (CNS) dysfunction, elevated antithyroid antibodies, the absence of infection or structural abnormalities in the CNS, and a response to treatment with steroids. The relationship between thyroid antibodies and encephalopathy has remained unresolved.

DESIGN/METHODS

Retrospective chart review.

RESULTS

We identified 13 patients who met the criteria for the diagnosis of HE. The median age was 49 years (range, 2-66) and all except one were women. Encephalopathy in the form of altered mental status, stroke-like symptoms or seizures, with prompt resolution of symptoms upon receiving steroids, was the commonest presentation, seen in 7 patients. The second commonest presentation was subacute progressive decrease in cognitive function, which reversed within days to weeks after steroid therapy, seen in 4 patients. Electroencephalogram (EEG) was available in 12 patients and was abnormal in 8, showing nonspecific cerebral dysfunction in all 8 and epileptiform activity in 3. Treatment consisted of steroids in the acute phase for 12 of 13 patients with rapid improvement in symptoms. Maintenance therapy was rituximab in 7 patients, intravenous immunoglobulin (IVIg) in 7, azathioprine in 4, mycophenolate mofetil in 3, and methotrexate in 1 (some patients received sequential therapy with different agents). There was complete or near complete resolution of symptoms in 12 of the 13 patients.

CONCLUSIONS

We present a cohort of patients in whom CNS dysfunction was associated with elevated antithyroid antibodies and reversal of disease followed immunomodulatory therapies.

Steroid-responsive recurrent encephalopathy associated with subacute thyroiditis

Background

Steroid-responsive encephalopathy associated with subacute thyroiditis has, to our knowledge, not been reported previously.

Case Report

A 49-year-old woman was found collapsed and brought to our institution with decreased mentality, dysarthria, and gait disturbance. Brain magnetic resonance imaging and angiography were normal but blood tests revealed thyroid-autoantibody-negative thyrotoxicosis. Results of a ^99mtechnetium-pertechnetate scan were compatible with the thyrotoxic phase of subacute thyroiditis. 14-3-3 proteins were detected in cerebrospinal fluid. Her mental status began to improve from the day following steroid administration. Recurrent encephalopathy was found 2 months after the initial admission, which was also effectively treated with steroid.

Conclusions

We speculate that steroid-responsive recurrent encephalopathy associated with subacute thyroiditis is a subtype of Hashimoto's encephalopathy, and consider that steroid treatment should not be delayed in suspected patients.

Autoimmune Encephalopathies

BACKGROUND

Evaluation of patients with recent onset of progressive cognitive and behavioral problems can be challenging. Psychiatric disorders, metabolic derangements, toxins and infections are generally considered in the differential diagnosis along with prion disorders (Creutzfeldt-Jakob disease) and rapidly progressive degenerative dementias. Some subacute encephalopathies are caused by autoimmune or inflammatory mechanisms, recognized by the association with autoantibody markers and/or clear response to immunomodulatory treatment. This review describes the clinical features of these potentially reversible autoimmune encephalopathies.

REVIEW SUMMARY

Morvan syndrome, paraneoplastic limbic encephalitis (PLE), and nonparaneoplastic autoimmune limbic encephalitis have characteristic clinical and serological features. Limbic encephalitis is characterized by short-term memory impairment, complex partial temporal lobe seizures and psychiatric symptoms. Signal abnormalities in the mesial temporal lobes without contrast enhancement are the typical MRI findings. Morvan syndrome presents with behavioral changes, hallucinations, severe insomnia, autonomic hyperactivity and neuromyotonia (spontaneous muscle activity). Corticosteroid-responsive encephalopathy associated with evidence of thyroid autoimmunity (sometimes called Hashimoto encephalopathy) has a broad range of clinical presentation. Cognitive impairment with tremor, seizures, stroke-like events (including transient aphasia) and normal thyroid hormone levels is a common scenario. In the absence of diagnostic serological findings, clinical improvement with corticosteroids may be the only evidence of autoimmune encephalopathy.

CONCLUSIONS

Autoimmune encephalopathies are an important cause of rapidly progressive cognitive and behavioral decline that probably remain under recognized. Electroencephalography, brain MRI, cerebrospinal fluid examination and serological tests are useful diagnostic tools. With increased clinical suspicion, these diseases may be diagnosed and treated successfully.