Lyme Optic Neuropathy

URGENT — Neuro

Symptoms

Endemic regions: Northeast (Virginia → Maine) and upper Midwest (Wisconsin/Minnesota) United States account for the vast majority of US cases; also Pacific Northwest and most of Europe.

Bimodal age distribution: children 5–15y often present with neurologic manifestations (CN VII palsy, meningitis); adults 45–65y more often present with arthritis and late manifestations.

Tick exposure (Ixodes scapularis in US, I. ricinus in Europe) in spring/summer — most cases May–August. Consider Lyme higher on the optic neuritis differential in July/August than you would for an MS-pattern presentation.

Subacute monocular visual loss (days to weeks) — may mimic demyelinating optic neuritis.

Pain on eye movement when true optic neuritis form — not universal.

Blurred vision with central or cecocentral scotoma.

Early localized (days–weeks after bite): erythema migrans rash (bulls-eye), flu-like illness, arthralgia, headache.

Early disseminated (weeks–months): cranial neuritis (especially CN VII palsy, often bilateral), meningitis, carditis with AV block, migrating oligoarthritis.

Migratory arthralgia — joint pain that shifts from one large joint to another over days (classic Borrelia signature); high-yield on history.

Late disseminated (months–years): chronic arthritis, encephalopathy, peripheral neuropathy, acrodermatitis chronica atrophicans (Europe).

Recent tick exposure, outdoor activity in endemic region, or known tick bite in the last weeks to months?

Prior erythema migrans rash (even if transient)?

Cranial nerve palsies — facial droop, diplopia, hearing loss?

Headache, neck stiffness, or photophobia (meningitic features)?

Clinical Findings

Reduced visual acuity, dyschromatopsia (especially for red), and a relative afferent pupillary defect (RAPD) in unilateral disease.

Optic disc edema — most common ocular manifestation of Lyme optic nerve involvement (either true papillitis or papilledema from Lyme meningitis).

Retrobulbar optic neuritis with a normal disc acutely is possible (indistinguishable from MS-type optic neuritis without serology).

Central, cecocentral, or altitudinal visual field defect on perimetry.

Reduced RNFL thickness on OCT after the acute edema subsides.

Vitritis — mild-to-moderate vitreous cells favor Lyme over MS-type optic neuritis (where the vitreous is typically clean).

Peripheral anterior or intermediate uveitis may coexist.

Episcleritis, keratitis, or conjunctivitis in a minority.

Bilateral disc swelling if raised ICP from Lyme meningitis.

Unilateral or, classically, BILATERAL CN VII palsy — bilateral facial palsy in an endemic region is almost pathognomonic for Lyme.

Meningismus (nuchal rigidity, Kernig/Brudzinski) if Lyme meningitis present.

Erythema migrans if still within early stage.

Etiology

Borrelia burgdorferi sensu stricto — primary pathogen in North America.

B. afzelii and B. garinii — predominant in Europe; B. garinii especially associated with neurologic manifestations.

Proposed mechanisms: direct spirochetal invasion of the optic nerve, immune-mediated demyelination, or inflammation from contiguous Lyme meningitis causing raised ICP / papilledema.

Co-infection with Anaplasma, Babesia, or Ehrlichia (shared tick vector) should be considered when systemic illness is severe.

Red Flags

Bilateral disc swelling + headache + meningismus → Lyme meningitis with papilledema; urgent LP and IV therapy.

Rapidly progressive vision loss despite serology workup → do not delay empiric IV ceftriaxone in endemic region.

Optic neuritis + unexplained cranial nerve palsy (especially CN VII) → strongly suggests Lyme over MS.

Positive Lyme serology should not substitute for MRI — exclude demyelinating lesions and other compressive causes.

Investigations

Visual acuity, pupils (RAPD), color vision (Ishihara), automated perimetry (Humphrey 24-2 or 30-2).

Dilated fundus exam + OCT RNFL to document disc edema and track resolution.

Two-tier Lyme serology (CDC criteria): ELISA screen, followed by Western blot (IgM and IgG) if reactive or equivocal. Modified two-tier assays (two ELISAs) are becoming more common in some labs; the two-tier principle is unchanged.

Antibody window: IgM takes 2–4 weeks to appear, IgG 4–6 weeks — a negative test within the first week does NOT exclude Lyme. Re-test at 2–4 weeks if suspicion remains high.

MRI brain + orbits with gadolinium — rule out MS plaques and characterize optic nerve enhancement.

Lumbar puncture with opening pressure — CSF pleocytosis, elevated protein, intrathecal Borrelia antibody (CSF:serum antibody index).

PCR for Borrelia DNA in CSF has modest sensitivity; use alongside serology.

Consider co-infection testing (Babesia smear/PCR, Anaplasma/Ehrlichia PCR) in endemic regions with systemic illness.

Rule out alternative causes: syphilis (RPR/FTA-ABS), TB (QuantiFERON), sarcoid (ACE, chest imaging), MS (MRI, OCB).

Treatment

IV ceftriaxone 2 g daily × 14–28 days — first-line for neuroborreliosis including optic nerve involvement.

IV cefotaxime or penicillin G are acceptable alternatives.

Oral doxycycline 100 mg BID × 14–21 days — reserved for isolated peripheral Lyme disease without CNS involvement. Recent European data suggest efficacy in some neuroborreliosis cases, but for optic nerve involvement (vision at risk) IV ceftriaxone remains the preferred choice in the US.

Do NOT give steroids alone — they can promote spirochetal proliferation. If needed for severe inflammatory edema, only after effective antibiotic coverage is established.

Treat raised ICP (acetazolamide) if Lyme meningitis with papilledema.

Address co-infections if identified (atovaquone + azithromycin for Babesia, doxycycline for Anaplasma/Ehrlichia).

Clinical Pearl

Lyme disease is a great mimicker of multiple sclerosis. In endemic areas (Northeast US, upper Midwest, Pacific NW, Europe), always obtain Lyme two-tier serology before committing a patient to demyelinating-disease immunotherapy. Bilateral facial nerve palsy, erythema migrans, summer/spring presentation, or cranial neuropathy cluster should raise suspicion immediately. Treatment is IV ceftriaxone for any CNS involvement — oral doxycycline is inadequate for optic nerve or meningeal disease.

Differential Diagnosis

MS-related optic neuritis — the primary mimicker; MRI + OCB help distinguish
Neuromyelitis optica / MOG-IgG associated optic neuritis
Syphilitic optic neuritis
Sarcoid optic neuropathy
Tuberculous optic neuritis or meningitis with papilledema
NAION (non-arteritic anterior ischemic optic neuropathy)
Papilledema from idiopathic intracranial hypertension
Infiltrative optic neuropathy (leukemia, lymphoma)
Toxic/nutritional optic neuropathy (especially in co-endemic regions)