AIDS (HIV) Neurological Disease

Related Subjects: |AIDS (HIV) Neurological Disease |AIDS (HIV) Respiratory disease |AIDS Dementia Complex (HIV) |AIDS HIV Infection |AIDS(HIV) Gastrointestinal Disease |Acute Retroviral Syndrome (HIV) |HIV and Post-Exposure Prophylaxis (PEP) |HIV and Pre-exposure prophylaxis |HIV associated nephropathy (HIVAN) |HIV disease Assessment

🧠 Neurological disease in advanced HIV/AIDS is common because profound CD4+ T-cell depletion disrupts cell-mediated immunity, allowing (1) opportunistic pathogens (e.g., Toxoplasma, Cryptococcus, JC virus, CMV), (2) HIV-driven neuroinflammation (HAND), and (3) malignancy (primary CNS lymphoma) to emerge. In UK practice, a key “safety rule” is that new focal neurology, seizures, or altered mental status in a person with HIV (or at risk of HIV) should trigger urgent neuroimaging and targeted CSF work-up where safe, in line with NICE’s approach to recognising symptoms needing urgent neurological assessment/referral.

🧪 Immediate approach (UK bedside logic)

• First priorities: ABCDE, check capillary glucose, treat seizures, manage raised ICP.
• Risk stratify by CD4 / ART status:
  • CD4 <100: toxoplasmosis, cryptococcus, PML, CMV (and TB/fungal disease depending on exposure).
  • CD4 <50: CMV and PCNSL become more likely; multiple OIs may co-exist.
• Imaging before LP if focal deficit, seizures, papilloedema, or reduced GCS (to reduce herniation risk).
• Always think HIV testing in undiagnosed patients with compatible presentations; NICE promotes increasing opportunities to test in appropriate settings.

🧠 HIV-Associated Neurocognitive Disorders (HAND)

• Pathophysiology: persistent CNS viral reservoirs + chronic immune activation → synaptic dysfunction and subcortical “slowing” even with systemic viral suppression in some patients.
• Asymptomatic Neurocognitive Impairment (ANI)
  • Objective impairment on neuropsychological testing but no clear functional impact.
• Mild Neurocognitive Disorder (MND)
  • Cognitive impairment with measurable impact on day-to-day tasks (attention, executive function, processing speed).
• HIV-Associated Dementia (HAD)
  • Severe functional impairment (often motor + behavioural features); now less common with effective ART but still seen in late presenters.
• Management (UK principles): optimise ART, address comorbid drivers (depression, sleep, alcohol/drugs, vascular risk), screen for reversible causes, and avoid unnecessary anticholinergic/sedative burden. (NICE CKS summarises complications that persist despite modern ART.)

🧬 Primary CNS Lymphoma (PCNSL) in AIDS

• About:
  • Usually an EBV-associated diffuse large B-cell lymphoma arising in severe immunosuppression.
  • Classically occurs with very low CD4 (often <50 cells/µL).
• Clinical clues:
  • Headache, seizures, focal deficits, neuropsychiatric change; may mimic toxoplasmosis.
• Diagnosis:
  • MRI brain preferred; lesions may enhance and can be solitary or multiple.
  • CSF: may show EBV DNA (supportive, not definitive).
  • Definitive: stereotactic biopsy where safe/appropriate.
  • Important practical point: if biopsy is likely, avoid empiric corticosteroids unless needed for life-threatening mass effect (they can reduce diagnostic yield).
• Treatment (specialist MDT):
  • ART + high-dose methotrexate–based regimens are central; radiotherapy may be used in selected cases.
  • Management is covered in BHIVA malignancy guidance.

🦠 Opportunistic CNS infections

• Toxoplasma encephalitis
  • Mechanism: reactivation of latent Toxoplasma gondii cysts when cellular immunity collapses.
  • Exposure: undercooked meat; cat faeces (oocysts).
  • Features: headache, fever, confusion, seizures, focal deficits.
  • Imaging: typically multiple ring-enhancing lesions with oedema; often basal ganglia/thalamus involvement.
  • Testing: serum IgG often positive (prior exposure supports reactivation; a negative IgG makes toxo less likely).
  • Treatment: pyrimethamine + sulfadiazine + folinic acid (or alternatives such as pyrimethamine + clindamycin if sulfa-intolerant); then maintenance/secondary prophylaxis until immune reconstitution.
• Cryptococcal meningitis
  • Mechanism: inhaled yeast (often C. neoformans) disseminates haematogenously to CNS; high organism burden + raised ICP are major causes of death.
  • Features: headache, fever, meningism may be subtle; cranial neuropathies/visual symptoms suggest raised ICP.
  • Diagnosis: CSF cryptococcal antigen (high sensitivity) ± India ink; measure opening pressure and manage aggressively if raised.
  • Treatment: induction with liposomal amphotericin + flucytosine (then consolidation/maintenance with fluconazole). Modern evidence includes regimens evaluated in large trials such as AMBITION; UK summaries incorporate these data. :contentReference[oaicite:5]{index=5}
  • ART timing is critical: unlike many OIs, starting ART too early increases mortality (CNS-IRIS/raised ICP). Guidance commonly recommends deferring ART ~4–6 weeks after starting effective antifungal therapy.
• Progressive Multifocal Leukoencephalopathy (PML)
  • Mechanism: JC virus reactivation → oligodendrocyte injury → demyelination.
  • Features: progressive focal deficits (weakness, ataxia, visual field loss, dysphasia) with minimal systemic upset.
  • MRI: non-enhancing white matter lesions, typically no mass effect/oedema (unless IRIS develops).
  • Treatment: immune reconstitution with ART is the main therapy; paradoxical worsening can occur via PML-IRIS, where corticosteroids may be used case-by-case in specialist care.
• CMV encephalitis / ventriculo-encephalitis
  • Mechanism: CMV reactivation in profound immunosuppression.
  • Features: delirium/encephalopathy, seizures, focal signs; can co-exist with retinitis.
  • Treatment: ganciclovir (or valganciclovir) guided by specialist virology/infectious diseases.

🦶 Peripheral neuropathies in HIV

• Distal symmetric polyneuropathy (DSPN)
  • Mechanism: HIV neurotoxicity + immune activation; historically also medication-associated with older ART.
  • Features: burning pain, paraesthesia, numbness (stocking-glove), reduced ankle jerks.
  • Management: optimise ART, exclude/ treat contributors (B12 deficiency, diabetes, alcohol), neuropathic pain approach (often follows general neuropathic pain principles).
• Inflammatory demyelinating polyneuropathy (AIDP/CIDP-like)
  • Immune-mediated; may resemble Guillain–Barré.
  • Treat with IVIg or plasma exchange in the right clinical context + ART optimisation.

🧍‍♂️ Myelopathy

• HIV-associated vacuolar myelopathy
  • Mechanism: chronic HIV-related spinal cord injury (vacuolation, especially dorsal/lateral columns), often with advanced disease.
  • Features: spastic paraparesis, gait disturbance, sensory symptoms, bladder dysfunction.
  • Management: ART + rehab; exclude compressive, B12/copper deficiency, and infective causes.

🛡️ Prevention & longer-term management (UK-focused)

• Start and sustain ART: BHIVA advises offering ART to all, typically within 2–4 weeks of diagnosis, with exception pathways for specific CNS OIs (notably cryptococcal meningitis).
• Prophylaxis:
  • Use OI prophylaxis in advanced disease and stop/restart based on immune recovery; BHIVA provides CD4/viral-load thresholds (e.g., for PCP prophylaxis discontinuation after sustained CD4 recovery/viral suppression).
• Monitor for CNS-IRIS after ART initiation: paradoxical inflammatory deterioration can occur as immunity returns, especially with high organism burden infections; recognise early because management (including cautious steroids in selected scenarios) can be life-saving.
• NICE referral mindset: persistent abnormal neurological signs/symptoms should trigger timely specialist assessment and investigation pathways rather than watchful waiting when serious secondary causes are plausible.

📚 References (key guidance)

• NICE NG60 HIV testing: increasing uptake (2025).
• NICE NG127 Suspected neurological conditions: recognition and referral (last reviewed 2023). :contentReference[oaicite:13]{index=13}
• NICE CKS HIV infection and AIDS (complications and UK primary care summary).
• BHIVA Opportunistic infections, viral hepatitis and virology (PDF, 2025).
• BHIVA ART guidelines for adults living with HIV-1 (2022).
• BHIVA Malignancy guidelines (PCNSL section) (2014).
• EACS Guidelines v12.0 (2023) (European consensus reference).
• NIH OI guidelines Cryptococcosis: defer ART 4–6 weeks after antifungals (updated 2024).