Neuro ID

Meninges (inside to outside): brain surface → pia[…] mater → arachnoid[…] mater → dura[…] mater.

The pachymeninges[…] refers to dura; the leptomeninges[…] refers to pia and arachnoid.

Infectious meningitis mostly affects the leptomeninges[…].

Pachymeningeal[…] enhancement is seen in fungal, TB, and syphilis[…] meningitis.

Definitions: chronic[…] meningitis lasts >1 month without improvement.

Meningoencephalitis[…] = meningitis + AMS.

Chemical[…] meningitis is from dermoid or craniopharyngioma rupture.

Classic tetrad: fever, headache, stiff neck, and AMS[…]. About 95% of patients have at least 2 of the 4 features; less than half have all 4.

Meningismus signs (meningeal irritation) include nuchal rigidity[…], the Kernig[…] sign (pain/resistance with passive knee extension while hip is flexed), and the Brudzinski[…] sign (hip/knee flexion with passive neck flexion).

These are specific but not sensitive[…] and may be absent in patients on analgesics[…], >65 yo, or immunocompromised.

Complications: seizures, strokes from infectious vasculitis[…], hydrocephalus (usually noncommunicating[…] from destruction of arachnoid granulations[…]), and cranial neuropathies (especially fungal and TB[…]).

Bacterial: PMN pleocytosis[…], normal-to-elevated protein, hypoglycorrhachia[…] (glucose <40, from GLUT transporter[…] dysfunction and consumption).

Viral: lymphocytic pleocytosis[…] (may start PMN), elevated protein, normal glucose — except WNV, CMV ventriculitis, enterovirus, and mumps[…] which can show low glucose.

TB/Fungal: lymphocytic pleocytosis[…], high protein, hypoglycorrhachia[…].

Syphilis: CSF VDRL[…] is highly specific but not sensitive — if negative but suspicion is high, send CSF FTA-ABS[…].

Routine sends: ME panel[…] + Crypto Ag ± Lyme, TB, Syphilis ± 1,3-β-D glucan (Candida) ± CSF IgG:serum IgG ratio (Sporotrichosis).

MRI brain in bacterial meningitis: T2 hyperintensity in sulci[…] with diffusion restriction + leptomeningeal[…] enhancement on T1 post.

Fungal meningitis: thick, nodular, basilar leptomeningeal[…] enhancement + hydrocephalus[…] + infectious vasculitis leading to deep[…] strokes.

Cryptococcus meningitis: may show cryptococcomas[…] or "soap bubble[…]" appearance from dilated perivascular spaces forming gelatinous pseudocysts.

Adults/children: mostly Strep pneumo[…], N. meningitidis[…], and Listeria[…] if old/immunocompromised.

Infants: E. coli, GBS, and Listeria[…].

Risk factor mapping: Strep pneumo: splenectomy[…] and IgA deficiency.

N. meningitidis: purpuric rash[…]; risk increases 2000× with eculizumab[…] → vaccinate first.

H. flu: now rare unless unvaccinated[…] child.

Staph: undiagnosed CSF leak[…] or skin breach (IVDU).

Listeria: old or immunocompromised; can cause rhombencephalitis[…] (CN palsy, ataxia, AMS).

Standard coverage: vancomycin + ceftriaxone[…] + ampicillin[…] (if >50yo or immunocompromised, for Listeria) ± dexamethasone[…] (beneficial only if Strep pneumo[…] meningitis). Strep pneumo dexamethasone benefit: reduces unfavorable outcomes.

Enterovirus: common, with a GI prodrome[…].

HSV-1 more commonly causes encephalitis[…]; HSV-2 more commonly causes meningitis[…] and recurrent Mollaret[…] meningitis.

Treat with IV acyclovir 10 mg/kg TID × 10-14 days[…].

VZV: can cause vasculitis → stroke[…]. WNV: #1 summer epidemic viral meningitis in US.

Treatment is supportive[…].

Mumps: can cause CSF hypoglycorrhachia[…].

Arboviruses: best diagnosed with CSF IgM[…].

Cryptococcus: elevated ICP requiring serial LPs[…], sometimes VPS.

Treat IV amphotericin B + flucytosine[…].

Coccidioidomycosis: Southwestern US[…]. Treat fluconazole. Histoplasmosis: Mississippi and Ohio river valleys, associated with pulmonary disease.

Treat liposomal amphotericin B[…] then itraconazole. Blastomycosis: similar geography to histoplasmosis. Treat liposomal amphotericin B then azole. Candidiasis: in immunocompromised with neutropenia.

Treat liposomal amphotericin ± flucytosine[…] then fluconazole; remove infected devices. Sporotrichosis: gardening/agriculture exposure. Treat liposomal amphotericin then itraconazole.

Naegleria fowleri: swimming in warm water → enters via cribriform plate[…] → rapidly fatal "primary amoebic meningoencephalitis." Treat IV/IT amphotericin B[…].

Chronic meningitis DDX includes infectious (TB, fungal, syphilis, Lyme) and noninfectious (sarcoidosis, IgG4 disease, malignancy[…]).

TB meningitis: commonly causes cranial neuropathies[…] (granulomatous basilar meningitis) and subcortical strokes[…].

Treat RIPE[…] (rifampin, isoniazid, pyrazinamide, ethambutol) ± dexamethasone.

Neurosyphilis (meningovascular): consider in HIV/STI[…] history with chronic meningitis.

Treat PCN G[…] (or ceftriaxone if PCN-allergic).

Lyme (Borrelia burgdorferi): tick-borne, with erythema migrans[…].

Treat IV ceftriaxone[…] or PO doxycycline.

Definition: inflammation of brain parenchyma[…]; may involve meninges[…] (meningoencephalitis) or spinal cord[…] (encephalomyelitis).

Symptoms: acute-to-subacute AMS >24h[…] (contrast with tauopathies/prion disease, which are slower), ± FNDs and seizures.

Empiric coverage: bacterial — ceftriaxone, vancomycin[…] ± ampicillin[…] (elderly, immunocompromised); viral — IV acyclovir[…].

Tropism: hits temporal[…] lobe and limbic[…] structures → AMS with amnesia, behavioral changes, temporal lobe seizures[…], and olfactory[…] hallucinations.

Pathophys: moves via olfactory and trigeminal[…] nerves (retrograde axonal transport) to the CNS, usually with a URI prodrome.

MRI: mesial temporal, orbitofrontal, and insular[…] regions with diffusion restriction.

Early on, unilateral[…] typically.

EEG: LPDs[…] with possible electrographic seizures. CSF: lymphocytic pleocytosis, elevated protein, normal glucose.

Treatment: IV acyclovir 10 mg/kg TID[…] × 10-14 (up to 21) days.

SE: obstructive nephropathy[…] from precipitation in renal tubules → reversible with maintenance IV fluids.

Post-HSV autoimmune encephalitis: relapse after PCR-proven HSV → test CSF/serum anti-NMDA-R antibody[…].

Mechanism: causes a vasculopathy[…] from infection of small/large cerebral artery walls. Risk: shingles reactivation more common in immunocompromised or elderly, often with a history of chickenpox.

Diagnosis: VZV PCR has lower[…] sensitivity than HSV PCR — add CSF anti-VZV IgG[…] if PCR is negative.

MRI in VZV vasculopathy: multifocal strokes at the gray-white junction[…] in multiple vascular territories, often contrast-enhancing[…] (atypical for typical strokes).

MRA may show beading[…].

Treatment: IV acyclovir[…] ± short course of steroids[…].

EBV: Alice in Wonderland[…] syndrome (distorted visual/body perceptions) or opercular[…] syndrome (facial/pharyngeal/masticatory weakness).

HHV-6: limbic[…] encephalitis. Treat ganciclovir and foscarnet.

CMV: retinitis, ventriculitis, polyradiculitis[…]. Treat ganciclovir and foscarnet.

Listeria: rhombencephalitis[…] — progressive asymmetric CN palsies and cerebellar signs.

MRI shows multiple enhancing dorsal brainstem[…] lesions.

Treat ampicillin[…].

Rabies: dog bite → days-to-years incubation → agitation, hydrophobia[…], delirium, seizures, ascending paralysis → coma/death.

Diagnose rabies antigen from hair follicles[…].

Treatment: post-exposure prophylaxis[…] (no cure once symptomatic).

SSPE: chronic measles[…] reactivation — fatal.

Pattern: meningoencephalitis ± myelitis. Diagnose with CSF IgM[…].

Flaviviruses can hit deep gray matter (BG/thalamus)[…], causing movement disorders.

WNV: preferentially affects basal ganglia and thalamus[…] → parkinsonism.

Some develop neuroinvasive[…] disease with acute flaccid myelitis[…] (anterior horn cell tropism, preserved sensation).

Diagnostic test: CSF WNV IgM[…] (intrathecal synthesis). No specific treatment. Japanese Encephalitis Virus: fever/HA prodrome → AMS/SZ/FND/movement disorders (tremor, rigidity, masklike facies, dystonia/chorea), may have acute flaccid myelitis.

Rocky Mountain Spotted Fever (Rickettsia rickettsii): often kids; abrupt fever, HA, restless delirium → rash 3-5 days[…] after fever onset starting on wrists/ankles[…] → becomes petechial[…].

Other features: retinal vascular changes, temporary hearing loss, thrombocytopenia[…].

Treatment: doxycycline[…].

Naegleria fowleri: freshwater/soil exposure → nasal passages → fulminant Primary Amoebic Meningoencephalitis (PAM)[…].

Classic risk: nasal tap-water irrigation[…].

Acanthamoeba: Granulomatous Amoebic Encephalitis (GAE)[…] — meningoencephalitis with hydrocephalus, may show necrotic mass lesions[…] on MRI. Diagnose by CSF PCR.

Definition: contained[…] infections — HA and focal deficits without consistent fever (unlike meningoencephalitis). DDX: malignancy, radiation necrosis, demyelination.

Pathophys: early cerebritis[…] (edema, necrosis) → late cerebritis → encapsulation with a fibrotic capsule.: Sinusitis[…] → frontal or temporal abscess; Otitis media (PSAR)[…] or mastoiditis → temporal lobe or cerebellum.

MRI: hypointense rim[…] (free radicals from phagocytic macrophages) with rim enhancement + intense central diffusion restriction[…].

MRI spectroscopy: elevated lactate[…].

Treatment: Nonsurgical for <2.5 cm or early cerebritis: ceftriaxone + metronidazole[…]. Postsurgical or traumatic: vancomycin + cefepime.

IV for 6-8 weeks[…]. Surgical (stereotactic aspiration vs excision) for solitary, superficial, multiloculated, or posterior fossa abscesses.

Pathogen: Plasmodium falciparum[…]. Sporozoites enter via mosquito bite → liver → reproduce as schizonts → infect RBCs → trophozoites → cyclic fever.

Enters CNS via olfactory nerve or bloodstream[…].

Pathology: sequestration of infected RBCs in cerebral microvasculature → "flea-bitten" ring hemorrhages[…] in white matter. Symptoms: fever, AMS, possibly seizure → progressing to coma.

Diagnostics: blood smear[…] for parasite forms; fundoscopy[…] for retinal hemorrhages/whitening and papilledema.

Treatment: IV artesunate[…] (superior to quinine).

SE: delayed hemolysis[…].

Mechanism: host = cats[…]; cysts/oocysts contaminate food/water.

Latent infection reactivates in immunocompromised (HIV with CD4 < 100[…], transplant).

Symptoms: subacute fever/HA/seizure + visual[…] symptoms ± hyperkinetic movement disorders (BG predilection).

MRI: T1 hypointense, T2 hyperintense ring-enhancing[…] lesions with perilesional edema, most commonly in basal ganglia or subcortical[…] regions (often multifocal).: "Eccentric target[…]" sign — ring enhancement with a small eccentric nodule along the wall; "Concentric target[…]" sign — concentric alternating T2 hypo/hyperdensity zones; Hypometabolic[…] on PET (opposite of lymphoma). Serology: positive IgM or rising IgG suggests acute infection.

Treatment: TMP-SMX[…] (now widely used vs traditional pyrimethamine/sulfadiazine/leucovorin) × ≥6 weeks ± steroids if edema/mass effect ± ART[…] 2+ weeks after starting antiparasitic therapy to avoid IRIS[…].

Mechanism: cyst larval form of Taenia solium[…] → pigs intermediate → humans eat undercooked pork → harbor adult tapeworm.

Fecal-oral[…] ingestion of eggs leads to neurocysticercosis.

Symptoms: HA/seizure ± hydrocephalus[…] (ventricular involvement), chronic arachnoiditis[…] (subarachnoid form), or myelopathy (spinal cord).

Imaging: CT[…]: better for calcifications.

MRI[…]: more sensitive overall, especially extraparenchymal.

Look for scolex[…] (eccentric nodule within the cyst). Monitor response: circulating parasite Ag (reflects live cysticerci).

Treatment: albendazole + praziquantel[…] (worsen symptoms temporarily as cysts die — give steroids + ASMs concurrently).

VPS[…] for hydrocephalus or neuroendoscopic cyst removal as needed.

Mechanism: Schistosoma[…] trematode flukes penetrate skin in freshwater → migrate through portal venous system → mature → migrate to GI tract or bladder → lay eggs.

Can move via Batson venous plexus[…] (retrograde from iliac/IVC) into the spinal cord/brain. Cerebral form: HA, AMS, chronic pseudotumor mass with possible parenchymal/SAH from small BV damage.

Spinal form: transverse myelitis[…] from granulomatous lesion with inflammation/necrosis, often affecting lower (T11-L1)[…] spinal cord.

Can have conus/cauda equina involvement with sphincter/sexual dysfunction or acute paraplegia from anterior spinal artery[…] occlusion by parasites.

Imaging: cerebral form shows subcortical mass lesions[…] with heterogeneous contrast enhancement in an "arborized" pattern (linear, surrounded by multiple enhancing nodules). Spinal form shows cord enlargement with heterogeneous enhancement of nerve roots.

Diagnostic test: stool/urine[…] for eggs.

Treatment: steroids + praziquantel[…]; rarely surgery.

Latent → reactivation in immunocompromised state (HIV, tobacco/EtOH, DM, ESRD). HIV[…] is the strongest single risk factor.

Tuberculous meningitis: fever, HA, AMS, cranial neuropathies[…] (esp CN VI, VII, III), with thick purulent exudates in basal cisterns[…].

Strokes commonly in basal ganglia[…] (small arteries near basal cisterns); seizures, hydrocephalus, FNDs all from inflammation or tuberculomas. Stroke mechanism: inflammatory basal cistern exudates + inflammatory arteritis + hypercoagulability + platelet dysfunction.

IRIS[…] (immune reconstitution inflammatory syndrome) can occur in HIV co-infection on ART — paradoxical worsening. Tuberculomas: granulomatous space-occupying lesions.

Encapsulated mass forms = "rich[…]" foci. Can expand with IRIS.

Tuberculous abscesses: similar but pus[…]-filled.

Spinal TB: most commonly thoracic and lumbar[…] levels.

Pott disease (spondylitis): back pain, gibbus[…] formation → kyphosis, and myelopathy (sensory, bowel/bladder, paraparesis).

Can cause vertebral fracture[…] or abscess → cord compression. Spread: exudates can settle in the lumbosacral subarachnoid space → spread to conus or cauda equina → bowel/bladder/sexual dysfunction, areflexic paraparesis.

Late complication: syrinx[…] formation.

MRI spine: vertebral body destruction/edema with paravertebral exudates, involving ≥3 consecutive vertebrae with sparing of intervertebral discs[…]. Subligamentous spread with vertebral collapse and thin-walled abscess. Other extraparenchymal: optic neuropathy, limbic encephalitis.

Imaging signs: MRI brain: tuberculomas (often with perilesional edema), leptomeningeal enhancement, infarcts, hydrocephalus; "Target[…]" sign: central calcification with rim of enhancement (also seen in neurocysticercosis[…]).

CSF: lymphocytic pleocytosis, low glucose, high protein[…]. AFB stain has low sensitivity.

Mycobacterium culture[…] is gold standard.

Definitive test for tuberculomas/abscesses: brain biopsy[…].

Treatment: RIPE[…] (rifampin, isoniazid, pyrazinamide, ethambutol) × 2 months → then RI[…] (rifampin/isoniazid) for the rest of the year ± adjuvant steroids.

Treat until contrast enhancement[…] resolves.

Drug side effects: INH: seizures and peripheral neuropathy[…]; Ethambutol: optic neuropathy[…]; Rifampin: potent CYP450[…] inducer.

HIV co-infection: early ART[…] initiation, especially if CD4 < 50. ASA in some patients with strokes.

Prevalence: neurosyphilis occurs in all stages (1-3)[…], more in HIV[…] (impaired clearance) and MSM.

Early presentations: Meningoencephalitis[…] → meningovascular[…] disease (vasculitis-induced strokes, often MCA[…] territory, in young sexually active individuals with recurrent unexplained strokes); Ocular and auditory[…] involvement; Cranial neuropathies (commonly CN II, VII, VIII[…]); Syphilitic gummas[…]: granulomatous mass lesions arising from pia[…] mater — contrast-enhancing.

Late presentations (years-decades): Tabes dorsalis[…]: demyelination of posterior columns, dorsal roots, dorsal root ganglia[…] → sensory ataxia, impaired proprioception, hyporeflexia, bowel/bladder dysfunction, lancinating[…] pains; Argyll-Robertson[…] pupils: react poorly to light but briskly to accommodation; General paresis: gradual personality/behavioral change, cognitive decline, psychosis, seizures; Syphilitic amyotrophy[…]: progressive anterior horn cell degeneration; Pure cerebellar ataxia.

Indication for LP: per CDC, only if patient has symptomatic neuro/ocular/oto-syphilis. Serum testing: Nontreponemal[…] tests (RPR, VDRL): initial screen; Treponemal[…] tests (FTA-ABS, RPPA): confirmatory, more sensitive. CSF testing: Lymphocytic pleocytosis + elevated protein.

CSF VDRL[…]: high specificity. If reactive → confirmed neurosyphilis.

If CSF VDRL nonreactive → order CSF treponemal[…] test (high specificity). Negative essentially excludes; positive supports but doesn't distinguish active from treated.

MRI: atrophy in frontal and temporal[…] lobes with subcortical FLAIR hyperintensities. MRA-VWI may show concentric wall enhancement in meningovascular syphilis.

Treatment: high-dose IV penicillin G × 2 weeks[…]; if allergic, IV ceftriaxone[…] 2g daily. Retreat if persistent CSF pleocytosis or if serum RPR/CSF VDRL fail to decline fourfold within 1-2 years.

Pathophys: COVID uses spike proteins to attach to ACE2[…] receptor.

AMS/encephalopathy[…] — most common in hospitalized patients, mostly from hypoxic/metabolic causes.

MRI: diffuse bilateral symmetric lesions with delayed posthypoxic leukoencephalopathy[…], microhemorrhages in corpus callosum and juxtacortical regions.

Anosmia/ageusia[…]: virus invades sustentacular[…] cells expressing ACE2 near olfactory nerves. MRI: olfactory bulb edema.

Acute Necrotizing Hemorrhagic Encephalopathy (ANHE)[…]: cytokine-release-driven.

MRI: bilateral symmetric hemorrhagic thalamic[…] lesions ± brainstem/temporal lobes, no enhancement.

Treat PLEX or IVIG[…]; does not respond to steroids.

Cytokine release syndrome[…]: AMS, tremor, ataxia, dysautonomia. Responds to steroids/IVIG.

ADEM[…]: AMS + multifocal deficits, FLAIR hyperintensities in deep white matter, perivenular demyelination. Treat steroids.

Central hypoventilation — "forgetting to breathe" with normal RR but desaturation. Possible transneuronal spread via vagus[…] nerve.

Stroke: hypercoagulable[…] state with arterial and venous mechanisms.

Pathophys: Virchow's triad[…] — ACE2-mediated endothelial injury + hypercoagulability + immobility.

For IVT, some prefer TNK[…] for rapid administration.

Transverse myelitis: often as longitudinally-extensive acute necrotizing myelitis[…] (≥3 segments).

GBS variants including Miller Fisher[…]. Myositis: paraspinal muscle involvement → rhabdo with renal toxicity risk.

Long COVID (Post-Acute COVID Syndrome): Dysautonomia[…]/POTS — treat with fluids, binders, stockings, midodrine, florinef, droxidopa.

Beta-blockers[…] can worsen. Extreme exercise intolerance.

Cognitive "brain fog"[…].

MIS-C[…] (multisystem inflammatory syndrome in children): 2-3 weeks after acute infection. AMS, dysarthria/dysphagia, weakness.

MRI: splenium of corpus callosum[…] restricted diffusion. Responds to IVIG/steroids.

Vaccine side effects: Bell's palsy, GBS, and vaccine-induced TTP[…] leading to CVST[…] with antibodies to PF4[…] — treat IVIG + non-heparin[…] anticoagulation.

At-risk populations: transplant recipients (solid organ — especially liver, heart, pancreas[…]) or HSCT — particularly increases PML[…] risk.

Symptom timeline: Early: pancytopenia with reactivation of latent[…] infections; Few months in: opportunistic[…] infections (JCV, Aspergillus); Late: varied.

IRIS[…] (immune reconstitution inflammatory syndrome): associated with TB, JCV, Cryptococcus[…].

Highest risk of latent infection reactivation: within the first month[…] after HCT.

Course: slower and progressive[…] compared to MS's focal deficits with short-term recovery.

More cognitive[…] symptoms vs MS.

Targets: JCV infects oligodendrocytes[…] → subacute cognitive/personality changes, seizures/ataxia, visual processing deficits (agnosia, hallucinations, hemineglect, hemianopia).

MRI: large, confluent, asymmetric T2 lesions[…] with subcortical involvement and no[…] enhancement usually.

May involve cerebellar peduncles[…] and deep gray.

Classic location includes middle cerebellar peduncle[…].

Compared to MS: less brainstem involvement, less frequent or peripheral enhancement (MS is homogeneous or open-ring); contrast enhancement appears with IRIS[…]. Cerebellar Granule Cell Neuronopathy: progressive cerebellar atrophy without lesions.

Diagnostics: CSF JCV PCR[…].

Treatment: stop natalizumab + PLEX[…]. If IRIS develops → high-dose steroids. Monitoring on natalizumab: MRI annually + JCV serology q6 months.

Risks: fingolimod[…] and steroids; AIDS; sarcoid on steroids; lymphoma; transplant.

Presentation: HA, n/v/fever, CN palsies[…], meningismus, vision changes from elevated ICP[…].

MRI: "soap bubble[…]" appearance from dilated perivascular spaces forming gelatinous pseudocysts (often basal ganglia[…]). Cryptococcomas as space-occupying lesions.

Can cause stroke from beaded vasculitis[…] on MRA. Even without mass lesions → elevated ICP and hydrocephalus. CSF: high OP, lymphocytic pleocytosis, high protein, low glucose.

Diagnostics: serum and CSF cryptococcal antigen[…].

Treatment: amphotericin B + flucytosine[…] ≥2 weeks → then fluconazole[…] maintenance. Manage ICP with serial LPs.

CMV ventriculitis: viremia → subacute cognitive changes, CN palsies, ataxia. MRI: ventriculitis[…] with ependymal enhancement and diffuse T2 hyperintensities. Diagnose CMV PCR.

Treat ganciclovir or foscarnet[…].

HHV-6 / Post-transplant Acute Limbic Encephalitis (PALE): primarily HSCT[…] recipients, 2-6 weeks post-transplant.

Amnesia, HA, confusion, seizures, hyponatremia[…].

MRI: bilateral medial temporal[…] lobe (uncus, fornix, amygdala) FLAIR signal with hippocampal atrophy later; no enhancement. CSF: lymphocytic pleocytosis. Treat foscarnet or ganciclovir. VZV in immunocompromised: vasculopathy, myelitis, cerebellitis after a preceding rash. Multifocal gray-white-junction strokes, often contrast-enhancing, with MRA beading.

Treat IV acyclovir[…] ± steroids.

PCNSL: non-Hodgkin lymphoma confined to brain/spine. Deficits similar to toxo but distinguished by vitreoretinal[…] lymphoma (vs chorioretinitis in toxo).

MRI: homogeneous, patchy, or rim[…] enhancement with restricted diffusion; single or multifocal lesions.

In HIV PCNSL: heterogeneous/reduced[…] enhancement (vs homogeneous in immunocompetent).

Diagnostics: EBV PCR, CSF cytology/flow cytometry → often biopsy[…] required.

Critical: avoid steroids[…] before diagnosis — decreases diagnostic yield.

Treatment: high-dose MTX[…] + steroids.

PTLD: post-transplant; vast majority are diffuse large B-cell lymphomas[…]. Multifocal lesions with ring or homogeneous enhancement. Diagnose same as PCNSL.

Aspergillus: rare meningismus (unlike Crypto). MRI: basal ganglia and thalami[…] infarcts/hemorrhages (small BV predilection) + brain abscesses.

Diagnose CSF galactomannan[…] + Aspergillus PCR. Often needs biopsy.

Treat voriconazole[…] ± neurosurgery.

Mucormycosis: risk in DM and heme malignancy[…].

Often starts sinonasal[…] → CNS extension. MRI: basal ganglia involvement with mycotic thromboembolic infarcts/abscesses. Diagnose with biopsy.

Treat amphotericin B[…] + surgery. Invasive Candidiasis: meningitis or vascular issues (infarcts, SAH, mycotic aneurysms). MRI: small enhancing lesions in deep gray or white matter.

Diagnose CSF 1,3-β-glucan[…]. Treat amphotericin B + flucytosine.

Nocardia: single or multiple ring-enhancing abscesses, often at the gray-white junction[…], after subacute pneumonia. Diagnose with biopsy.

Treat TMP-SMX[…] + other agents.

VZV myelopathy: vasculopathy → spinal cord infarction[…]. Treat acyclovir/steroids.

CMV polyradiculomyelitis: early bowel/bladder[…] dysfunction, hypotonic weakness, hyporeflexia. EMG/NCS needed. Diagnose CSF CMV PCR.

HSV myeloradiculitis: HSV-2[…] more often than HSV-1 → cord T2 hyperintensities, contrast-enhancing. Treat IV acyclovir. Can also present as transverse myelitis.

Rituximab/Ocrelizumab[…] (anti-CD20): predisposes to EBV-associated PCNSL, toxoplasmosis, PML (JCV)[…].

Natalizumab[…] (α4 integrin): risk of PML (JCV)[…].

Eculizumab[…] (anti-C5): risk of N. meningitidis[…] — requires vaccine first.

Alemtuzumab[…] (anti-CD52): PPX with acyclovir[…] × 1 month after treatment for herpes prevention.

Fingolimod[…] (S1P): predisposes to shingles, HSV encephalitis/vasculitis, and Cryptococcus[…] meningoencephalitis.

Dimethyl fumarate[…]: PML risk with moderate-severe lymphopenia.

TORCH = Toxoplasmosis, Other (Zika, Syphilis), Rubella, CMV, HIV/HSV[…].

Transmission: transplacental, birth canal, or breastfeeding[…]. Earlier infection = more severe disease.

Common symptoms: sensorineural hearing loss, chorioretinitis, petechiae/purpura, hepatosplenomegaly, cerebral malformations[…].

Transmission: cats[…] → humans.

Symptoms: macro[…]cephaly, cerebral calcifications[…], and seizures (also SNHL, HSM, petechiae, chorioretinitis).

Diagnosis: IgM[…] antibody (does not cross placenta), Toxoplasmosis PCR.

Prevention: pregnant women avoid cat litter[…].

Treatment: spiramycin[…] in first trimester (or pyrimethamine/sulfadiazine/leucovorin rescue later).

Transmission: mosquitoes[…] → humans.

Symptoms: fever, maculopapular rash[…], severe microcephaly[…] with partially collapsed skull, thin cortex with subcortical calcifications[…], macular scarring, congenital contractures, early hypertonia.

Imaging: subcortical calcifications, abnormal cortical development including lissencephaly and pachygyria[…], prominent occipital bone, enlarged torcula, hypoplastic CC/brainstem, shallow sulci. Diagnosis: positive IgM antibody and PCR. Prevention/treatment: none.

Transmission: STI to mother → fetus. Symptoms: maculopapular rash, osteochondritis[…], nasal secretions → late: meningitis, strokes, hydrocephalus, SNHL. Newborns may show fourfold higher titer than mother.

Diagnosis: screen with nontreponemal (RPR/VDRL)[…] → LP for CSF VDRL[…]. Prevention: treat maternal syphilis.

Treatment: IV/IM PCN G[…] × ~2 weeks.

Rubella: respiratory droplet transmission. Symptoms: cataracts[…], SNHL, cerebral calcifications and WMH, "blueberry muffin[…]" rash, chorioretinitis, HSM. Diagnose PCR + IgM.

Prevention: vaccine[…]. Treatment: none.

CMV (congenital): cerebral calcifications, atrophy, schizencephaly[…], cerebellar hypoplasia, ventriculomegaly. Diagnose PCR.

Treatment: IV ganciclovir or PO valganciclovir[…] — SE: neutropenia. HIV (congenital): cognitive issues, cerebrovascular disease, epilepsy. Diagnose PCR. Treat ART. HSV (congenital): HSV-1 via oral secretions postpartum; HSV-2 during peripartum.

Symptoms: microcephaly[…], chorioretinitis, vesicular rash.

MRI in neonates can be diffuse brain involvement[…] (vs classic temporal in older children). Treat acyclovir.

Relapse after PCR-proven HSV encephalitis should prompt CSF/serum testing for anti-NMDA-R[…] antibody — a known post-infectious autoimmune phenomenon.

Detection of HSV-1 in CSF[…] without signs of encephalitis necessitates empiric IV acyclovir[…] while awaiting confirmatory PCR. If confirmatory PCR is negative and the patient remains asymptomatic, antiviral therapy can be stopped safely.

Otherwise, typical duration is 14-21[…] days.

Neonatal HSV encephalitis shows diffuse bilateral cortical[…] enhancement with cortical ribbon disruption from neuronal necrosis on MRI.

Diabetic or dialysis patients with worsening back pain, radiculopathy, high ESR, and MRI showing vertebral osteomyelitis with a dorsal collection have a spinal epidural abscess[…] — needs urgent surgical decompression[…] (immediately if cord compression) plus IV antibiotics.

Staphylococcus aureus spinal meningitis classically shows diffuse thickening and enhancement[…] of the conus and cauda equina nerve roots on post-contrast T1.

A macular star[…] on fundoscopy is classic for Bartonella henselae[…] (neuroretinitis). Bartonella can also cause vertebral osteomyelitis with STIR hyperintensity and heterogeneous enhancement.

Sinusitis + frontal ring-enhancing lesion with DWI restriction and bone erosion = Streptococcus anginosus[…] brain abscess. MRI shows hypointense rim on FLAIR/T2, thick rim enhancement on T1+C, central diffusion restriction.

Subacute pneumonia followed by multiple supratentorial ring-enhancing[…] lesions at the gray-white junction → cerebral Nocardia[…]; treat TMP-SMX[…].

Lyme neuroborreliosis presents with lymphocytic meningitis[…], cranial neuropathies (esp VII)[…], and erythema migrans.

Treat doxycycline[…]. Children with Lyme meningitis more commonly have papilledema. Acute Lyme limb pain/weakness most often = mononeuropathy multiplex.

Isolated positive IgM[…] after >6 weeks is non-specific cross-reactivity. Isolated positive IgM in a low-risk patient is not chronic Lyme. Bell's palsy in a low-risk tick-area patient with normal CSF is not Lyme.

Lateral thigh pain with no Lyme exposure = meralgia paresthetica[…].

HIV-associated neurocognitive disorder (HAND)[…] = subtle executive dysfunction with nonspecific white matter changes in well-controlled HIV.

Vacuolar myelopathy[…] = spastic paraparesis with white-matter vacuolization on autopsy. HIV encephalitis shows diffuse leukoencephalopathy on FLAIR.

Distal symmetric polyneuropathy[…] is the most common neurologic complication of HIV.

Stavudine[…] can cause HIV-associated neuromuscular weakness syndrome (severe weakness, areflexia, hepatomegaly, lactic acidosis).

Disseminated histoplasmosis with CNS involvement shows multiple enhancing brainstem and longitudinally extensive cord[…] lesions on T1+C/T2.

Renal transplant on triple immunosuppression with focal deficits, perforator-territory infarcts[…] adjacent to a sphenoid fungal ball = angioinvasive CNS aspergillosis[…].

A Caribbean-origin[…] patient with insidious progressive spastic paraparesis, bladder dysfunction, distal vibration loss, and normal spine MRI = HTLV-1[…] myelopathy (tropical spastic paraparesis).

Bulbar-predominant cranial nerve palsies with EMG showing post-exercise CMAP increment[…] → botulism[…]; treat with antitoxin.

A 4-month-old with constipation, bulbar weakness, and hypotonia[…] = infant botulism.

Treat with BabyBIG[…] (IV botulism immunoglobulin).

Subacute bulbar neuropathy (tongue/gingival numbness, dysarthria, dysphagia) weeks after pharyngitis = Corynebacterium diphtheriae[…] neuropathy.

The most common neurologic manifestation of severe COVID-19 in hospitalized patients is encephalopathy[…].

Severe COVID can produce hypercoagulable large-vessel stroke (treat with thrombectomy[…]).

Post-COVID can produce POTS-like dysautonomia[…] from small-fiber autonomic neuropathy[…].

The "target[…] sign" can be seen in both neurotoxoplasmosis (eccentric target on MRI) and tuberculoma (concentric target on CT).

Response to therapy in neurocysticercosis is monitored with circulating parasite antigen[…] (reflects live cysticerci).

The subarachnoid form in basal cisterns causes hydrocephalus[…].

An asymptomatic-at-birth infant with progressive sensorineural hearing loss[…] and developmental delay should be evaluated for congenital CMV[…].

The meningococcal vaccine must be given before eculizumab[…] or any terminal complement inhibitor due to the dramatically elevated risk of N. meningitidis[…] infection.

Biphasic illness with brainstem-predominant cranial neuropathies (VII palsy, gaze limit, dysphagia) and pontomedullary[…] T2 lesions = Listeria[…] rhombencephalitis; treat ampicillin[…].

Classic risk factor: unpasteurized[…] milk.

Cryptococcal meningitis can show a "hazy brain base[…]" — bilateral lentiform/basal ganglia FLAIR signal from perivascular space involvement; can cause stroke from beaded vasculitis[…] on MRA.