Patient handout

Anti-LGI1 Encephalitis

PRODUCTION

1. Your condition

This handout is for anti-lgi1 encephalitis. Your care team identified this based on: older male (median age 60) with faciobrachial dystonic seizures (fbds) — short (1-3 sec) brief jerks of arm/face; pathognomonic for lgi1 (irani brain 2011 pmid 21416487).

Other reasons your team may use this plan: subacute memory loss + behavioural change + confusion ± seizures — limbic encephalitis with hippocampal involvement on mri; refractory hyponatremia (siadh) — occurs in ~60% of anti-lgi1; lgi1 hypothalamic expression; new-onset seizures in older adult highly responsive to high-dose ivmp — autoimmune epilepsy pivot.

2. Your medications

Take these medications exactly as prescribed. Do not stop or change a dose without talking to your provider.

Medication	Starting dose	How	When	What it does
methylprednisolone	1 g IV daily × 5 d	IV	daily × 5 d	First-line acute pulse; FBDS often dramatically responsive to high-dose IVMP within days; Graus 2016 PMID 26906964
IVIG	0.4 g/kg/day × 5 d (total 2 g/kg)	IV	daily × 5 d	First-line combo or alternative; Titulaer 2013 PMID 23290630
plasmapheresis (PLEX)	5 cycles q48h over 10 d	IV/large-bore	q2 days × 5	Severe or steroid+IVIG-refractory; alternative to IVIG
prednisone	60 mg PO daily × 2-4 wk then slow taper over 6-12 mo	PO	daily slow taper	Maintenance after IV pulse; slow taper over 6-12 mo to prevent relapse (~25%)

Plan: Anti-LGI1 acute IVMP pulse + IVIG/PLEX + slow taper + steroid-sparing + SIADH + AED + thymectomy if found (Graus 2016 PMID 26906964; Irani Brain 2011 PMID 21416487)

3. When to call your provider

Contact your care team if any of the following happen:

Breakthrough FBDS or seizure → escalate AED + consider repeat IVMP pulse
New memory loss / behaviour → ED + relapse workup
Severe SIADH → admit + tolvaptan + endocrinology
IgG <500 → IVIG / pause rituximab
Severe depression / suicidality → urgent psych

4. When to seek emergency care

Call 911 or go to the nearest emergency room right away if you have:

Older male (median age 60) with FBDS — short (1-3 sec) brief jerks of arm/face; pathognomonic for LGI1 (~50%); very steroid-responsive (Irani Brain 2011 PMID 21416487)
Subacute memory loss + behavioural change + hippocampal MRI T2/FLAIR — limbic encephalitis hallmark; persistent memory deficit if delayed Rx (PMID 20663977)
New-onset seizures in older adult dramatically responsive to high-dose IVMP — autoimmune epilepsy pivot; consider anti-LGI1 + other autoimmune AE panel (Irani Brain 2011 PMID 21416487)
Anti-LGI1 with thymoma (~10% paraneoplastic) — CT chest mandatory screen; thymectomy if found
Subacute rapid cognitive decline in older adult mimicking dementia — anti-LGI1 + other autoimmune AE panel must be sent; treatable dementia mimic
Relapse after immunotherapy taper (~25%) — re-induce IVMP pulse + add or escalate steroid-sparing (AZA/MMF) or rituximab; slow taper protocol
Rare concurrent anti-NMDAR + anti-LGI1 overlap — full autoimmune AE panel sent (CASPR2/GABA-B/AMPA/DPPX/mGluR5/IgLON5/Hu/Ma2/Ri/CV2)

5. Follow-up

Cognitive rehab (memory + executive deficit common — 60% have residua at 2 y); neuropsych at 3 + 6 + 12 + 24 mo; AED management if seizure history (carbamazepine effective specifically in FBDS but LEV preferred initial); slow steroid taper supervision (over 6-12 mo); SIADH follow-up + endocrinology if persistent; pre-DMT vaccinations; PHQ-9 + GAD-7 (post-encephalitis depression common)

6. Sources

Guideline: Graus 2016 IRCNS Position Paper Autoimmune Encephalitis Criteria + Irani Lancet Neurol 2010 LGI1 original description + Irani Brain 2011 FBDS pathognomonic + Titulaer 2013 treatment outcomes + LGI1 outcomes + LGI1 cognitive