Sunday, September 19, 2010

Clinical spectrum of voltage gated potassium channel (VGKC) autoimmunity


Tan KM, Lennon et al. Neurology 2008; 70:1883-1890. 
80 patients were found, 71 with clinical information available.  Mean age 65.
Neurologic symptoms were subacute or chronic including
1.  cognitive impairment 71 %-- see below
2.  seizures 58 %-- several types
3.  dysautonomia 33 %
4.  myoclonus  29 %
5.  dyssomnia 26 %
6.  peripheral nerve dysfunction 25 %
7.  EPS 21 %
8.  brainstem/cranial nerve dysfunction 19 %-- vision loss/blurred vision, diplopia, dysarthria, hemifacial spasm, facial numbness, anosmia.
9.  hypothalamic involvement-- 38 %-- hyponatremia (36 %) , hyperphagia, (8%) 
Common misdiagnosis was CJD (14 %)..  Other misdiagnoses:  viral encephalitis, recurrent TGA, generalized anxiety disorder, conversion disorder.
Associated tumors (paraneoplastic) 33 % confirmed histologically
carcinoma 18, adenoma 5, thymoma1, hematologic 3.
Associations
hyponatremia  36 %
other organ specific autoantibodies 49 %
coexisting autoimmune disorder 33 % (thyroiditis, DM)
34/38 responded to immunotherapy, half "vigorously" so.
Classic reports of association:
1.  Morvan's syndrome
2,  acquired neuromyotonia
3.  epilepsy
4.  limbic encephalitis
5.  dysatuonomia
6.  lung carcinoma
7. FACIAL BRACHIAL DYSTONIC SEIZURE
Cognitive presentation:
1.  frontosubcortical (personaltiy change, disinhibition,  executive dysfunction) 13 %
2.  Visual hallucination (10 %)
3.  Depression or agitation (13 %)

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