A Stitch in Time Saves Nine: A Case of Anti LGI1 Encephalitis Presenting as Goose Bumps

Sir, Anti-leucine-rich glioma-inactivated protein 1 (LGI1) encephalitis is the commonest autoimmune encephalitis in the elderly. It commonly presents with faciobrachial dystonic seizures (FBDS) or cognitive deterioration. Here we describe a case who presented with insomnia and ictal piloerection as initial manifestations of anti-LGI1 encephalitis without any cognitive symptoms. A 57-year-old man with no known co-morbidities presented to a local hospital with insomnia of one-month duration. He reported multiple episodes of goosebumps over the right side of the body (upper and lower limbs and trunk) lasting a few seconds which started at around the same time. These goosebumps occurred multiple times per day. There was no history of rising epigastric sensations or fear. There was no loss of awareness, orofacial automatisms, jerking of limbs, or fall. He had two episodes of visuospatial disorientation while driving as he did not turn his way and had to come back when his wife reminded him that they missed their way. There was no history of any cranial nerve symptoms, weakness, paraesthesia, or ataxia. There was no history of fever, headache, or vomiting. He also reported erectile dysfunction for a few days. There was no history of diabetes mellitus, hypertension, or hypothyroidism. On examination, he was alert-oriented to place, person, and time. He scored full scores in the Mini-Mental Status Examination and Montreal Cognitive Assessment. Outside investigations revealed mild hyponatremia (131 mEq/L) and a normal MRI Brain. CSF study indicated normal glucose, protein 41.4 mg%, and 6 lymphocytes/mm3. There was mild hyponatremia (Na 134 mEq/L) with normal serum osmolality (289 mOsm/Kg) and normal urine sodium (75 mEq/L). electroencephalogram (EEG) was normal. He was initially treated with brivaracetam but he continued to have recurrent goosebumps. Meanwhile, serum LGI 1 antibody came as positive. Serum and cerebrospinal fluid (CSF) anti LGI1 antibody was tested in another lab and both came as positive. He was started on intravenous methylprednisolone followed by oral prednisolone 40 mg/day and azathioprine with which his goose bumps subsided completely. He had another episode of goosebumps when prednisolone was reduced to 10 mg/day. He remained asymptomatic on the last follow up and his erectile dysfunction and insomnia subsided. LGI1 antibodies are probably the most common cause of limbic encephalitis and the second most common cause of autoimmune encephalitis after anti-N-methyl-D-aspartate receptor encephalitis. Patients with anti-LGI1 antibodies usually present with typical limbic encephalitis, including alteration of memory and behavior, spatial disorientation, and several types of seizures which are often drug-resistant. The semiological hallmark of anti-LGI1 encephalitis is FBDS which is seen in up to 50% of cases. FBDS present as short, stereotyped dystonic movements of the face and the ipsilateral arm or leg, frequently precede the onset of anti-LGI1 encephalitis.[1] These seizures are not always dystonic. Facio brachial motor seizures are a more apt description of these seizures.[2] FBDS appear earlier than other symptoms in many patients while tonic-clonic seizures often occur concurrently or immediately after a decline in patient cognitive function. Therefore, following FBDS, immediate immunotherapy treatment might prevent the development of cognitive impairment. Ictal piloerection (goosebumps) is a rare form of autonomic seizure and is considered to be principally caused by temporal lobe activity although frontal and hypothalamic seizure origins have been reported. It has been described in mesial temporal sclerosis, tumors, posttraumatic, cavernomas, and cryptogenic epilepsies.[3] Autoimmune limbic encephalitis (especially LGI1 and GAD 65 associated) and malignant brain tumors are the most frequently recognized aetiologies. Ictal piloerection as the only seizure type in LGI1 encephalitis is rare.[4] Few case reports have suggested pilomotor seizures as a specific manifestation associated with LGI1 antibodies. During the disease, 60%–88% of the patients develop hyponatremia, often presumed to be the result of the syndrome of inappropriate anti-diuretic hormone secretion. Sleep disorders are common in LGI1 encephalitis. These clinical features include insomnia, rapid eye movement sleep behaviour disorder, periodic limb movements in sleep, hypersomnia, agrypnia excitata, and obstructive sleep apnoea syndrome.[5] Approximately 70% of patients with LGI1 antibody encephalitis have increased T2 and FLAIR MRI signals in the hippocampus or temporal lobe and some can extend to the amygdala, insula, or striatum. In conclusion, anti-LGI1 encephalitis can present with insomnia and ictal piloerection without classical FBDS or cognitive deterioration. Early detection and treatment can prevent cognitive deterioration. Transient erectile dysfunction can occur during its course. It has a good prognosis when immunomodulatory drugs are started early. A combination of multiple motor semiologies, prominent thermal sensations, ictal piloerection, ictal cardiac arrhythmias, and frequent subclinical seizures should alert the clinician to the possibility of underlying LGI1-antibodies.[6] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

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