Serial perfusion brain tomographic scans detect reversible focal ischaemia in Rasmussen's encephalitis

Arterial spin labeling hyperperfusion in Rasmussen's encephalitis: Is it due to focal brain inflammation or a postictal phenomenon?

BACKGROUND AND PURPOSE

The study evaluated the utility of arterial spin labeling (ASL) perfusion imaging in Rasmussen's encephalitis (RE).

MATERIAL AND METHODS

The hospital electronic database was searched using the search words "encephalitis," "autoimmune encephalitis" and "Rasmussen's encephalitis" for the period of 1 Jan 2015 to 31 Jan 2017. Clinically diagnosed cases of RE for which epilepsy protocol magnetic resonance imaging (MRI) with perfusion imaging (ASL) performed on a 3T scanner were retrieved. The diagnosis of RE was based on Bien's criteria (Bien et al., 2005). We obtained patient's demographic details, clinical features, electrophysiological studies, and follow-up data from electronic hospital records.

RESULTS

We included nine patients with RE of whom seven patients showed increased perfusion, and two patients decreased perfusion. Among these patients, MRI changes of gyral hyperintensity without volume loss corresponded to regional ASL hyperperfusion in six patients and ASL hypoperfusion in one patient. Two patients who showed ASL hypoperfusion had corresponding atrophy on MRI. Eight patients of RE had epilepsia partialis continua (EPC) or daily seizures, and one patient was seizure-free post-surgery. Five patients showed a concordance of ASL hyperperfusion with clinical ictal onset zone. Among the seven patients with ASL hyperperfusion, the finding was concordant (complete or partial) with the electroencephalogram (EEG) ictal onset zone in six patients and with interictal epileptiform discharges (IED) in seven patients.

CONCLUSION

Increased perfusion in ASL of the involved brain parenchyma in RE is a common MRI finding and may be due to either active inflammation of the brain involved or a seizure-related finding.

Intravenous immunoglobulin therapy for autoantibody-positive cerebellar ataxia

OBJECTIVE

It has been reported that autoimmune cerebellar ataxias, such as anti-glutamic acid decarboxylase (GAD)-antibody-positive cerebellar ataxia and gluten ataxia, are treatable. Here, we examined the therapeutic efficacy of intravenous immunoglobulin (IVIg) on autoantibody-positive cerebellar ataxia.

PATIENTS AND METHODS

IVIg therapy was administered in seven autoantibody-positive cerebellar ataxia patients. Therapeutic efficacy was examined in terms of its effects on clinical symptoms and changes in brain perfusion using single photon emission computed tomography (SPECT).

RESULTS

Treatment was effective in four cerebellar cortical atrophy patients (two anti-GAD antibody-positive and two anti-gliadin antibody-positive) and in one anti-thyroid antibody-positive spinocerebellar ataxia type 3 (SCA3) patient, but not in two multiple system atrophy (MSA) patients. All four IVIg effective patients who underwent SPECT showed apparent increases in cerebellar perfusion.

CONCLUSION

If cerebellar ataxia with an autoimmune mechanism is suspected and radiological findings do not reveal MSA, it is worth considering immunotherapy including IVIg.

Advances in pathogenic concepts and therapeutic agents in Rasmussen's encephalitis

Rasmussen's encephalitis is a rare inflammatory brain disease which occurs mainly in children and is characterised by affection of only one hemisphere. Pathogenetic concepts have considered three different, not mutually exclusive, key factors contributing to the initiating or perpetuating events in the central nervous system. These include viruses, autoimmune antibodies and autoimmune cytotoxic T lymphocytes. Based on these concepts, different therapeutic strategies have been pursued, such as antiviral agents, plasmapheresis, immuno-adsorption, immunosuppression or immunomodulation with intravenous immunoglobulins. However, due to the lack of larger studies, to date there is no established therapeutic strategy of this devastating disease. An overview of the current state of immunepathogenic concepts for Rasmussen's encephalitis is given and past and present treatment attempts are discussed, including an outline of future perspectives. An opinion on symptomatic treatment with anticonvulsive drugs is included.

Rasmussen's encephalitis: a role for autoimmune cytotoxic T lymphocytes

The present review describes advances in Rasmussen's encephalitis (also known as Rasmussen's syndrome), an unihemispheric intractable epileptic disease with persistent inflammation. Specific attention is given to the recent recognition of cytotoxicity by CD8+/granzyme-B-positive T lymphocytes as a new pathogenic mechanism of neuronal damage.

Rasmussen's Encephalitis

When the diagnosis of Rasmussen's encephalitis is being considered, it is important to rapidly exclude other causes of epilepsia partialis continua and hemiparesis. Although there is no good data from randomized trials of different immune-related therapies, treatment with immunoglobulin G (IgG), steroids, or plasmapheresis is advocated as first-line therapy. It is not unreasonable to institute at least two treatment options (eg, IgG followed by plasmapheresis) if response to the first treatment is poor. Functional hemispherectomy and its variants are associated with a lower long-term complication rate.