Neuro

• Domperidone is the only anti-emetic that is safe to use in parkinson's disease Although domperidone is a dopamine antagonist, it does not cross the BBB unlike metoclopramide which does and is known for causing extrapyramidal side-effects
• Which anti-emtic is commonly known to cause extra-pyramidal signs? Metoclopramide
• A brain abscess is a life-threatening condition involving a localised, infectious collection of pus within the brain parenchyma, often encapsulated by a fibrous capsule Fibrous capsule contributes to the characteristic appearance of a ring-enhancing lesion on contrast CT/MRI. Contrast accumulates around the periphery within the fibrous capsule. Contrast CT [Credit: radiopaedia - cerebral abscess (summary)]
• ~50% of brain abscesses originate from infection of adjacent structure (e.g. otitis media, mastoiditis, dental infection, sinusitis)
• The most common microorganisms that cause brain abscesses are Staphylococcus aureus & Viridans streptococci common complication of local infection that extends to brain (e.g. otitis, mastoiditis sinusitis, dental)
• The most common cause of cerebral abscesses in HIV patients is toxoplasmosis (protozoa)
• Risk factors for brain abscess in a child: Otitis media Mastoiditis Dental infection Sinusitis Cyanotic heart disease "can be remembered with the mnemonic ""Oh My Dear Sweet Child"""
• Why are children with cyanotic congenital heart disease (e.g. tetralogy of Fallot) at an increased risk for brain abscess? R → L shunting of venous blood allows bacteria to bypass the pulmonary circulation and hematogenously spread
• Triad of symptoms for a brain abscess are headaches (dull, constant, progressively worsening ± localised), focal neurological deficits, & fever Brain abscesses present vaguely, suspect in patients with risk factors e.g. immunosuppression, recent neurosurgery, otitis media/sinusitis/mastoiditis
• Brain abscesses have a sudden or subacute (weeks) onset
• What symptom/clinical sign helps differentiate meningitis, encephalitis from brain abscesses? Focal neurological deficits Tumour is another important differential
• How do you differentiate between a brain abscess & tumour without biopsy? You can't They will both have headaches, N/V, fever, seizures, FNDs (yes, cancer can cause fever). Presentation of both is pretty nonspecific, even with a CT/MRI. Biopsy is done for final differentiation.
• What is the likely diagnosis in a child with a history of tetralogy of Fallot and recurrent sinusitis that presents with a two-week history of worsening morning headaches, fever, focal neurological deficits, and a recent first-time seizure? Brain abscess Congenital heart disease and recurrent sinusitis are important predisposing factors for brain abscess (right to left shunt bypasses the pulmonary 'filter' for bad stuff)
• Nausea/vomiting, headache and focal neuro deficits following otitis media is suggestive of brain abscess
• What is the best initial test for suspected brain abscess? CT with contrast (pre & post) MRI with contrast as well, but CT is an easier investigation to do.
• Brain abscess is often visualized on CT or MRI as a(n) ring-enhancing lesion with central necrosis Contrast accumulates in outer fibrous capsule
• What is the most accurate investigation for brain abscess? Biopsy Abscess vs Tumour → biopsy is needed to confirm which diagnosis CAN also aspirate. Abscesses are often polymicrobial, hence biopsy and culture is very important given that antibiotics regimens are rather long (4-5 months).
• Lumbar puncture is not done for suspected brain abscess because 1. possibility of herniation (esp. with ↑ ICP - absolute contraindication) 2. CSF is not diagnostically useful in most cases
• What is the differential diagnosis of ring-enhancing brain lesions on CT/MRI? GLAM GBM, lymphoma, abscess, metastasis Glibolastoma multiforme = GBM
• What are the main principles of management for brain abscess? Antibiotic therapy → initial then guided by cultures Surgical therapy → burr hole drainage / craniotomy if larger, multiloculated abscesses
• What is the empiric antibiotic therapy for brain abscess suspected Streptococcus spp. or Staphyloccal infection? Ceftriaxone & metronidazole (vancomycin if ↑ risk of MRSA) weeks of IV followed by oral antibiotics Consult microbiologists once culture is grown to specify antibiotics [Chow F. Brain and Spinal Epidural Abscess. Continuum (Minneap Minn). 2018 Oct;24(5, Neuroinfectious Disease):1327-1348. doi: 10.1212/CON.0000000000000649. PMID: 30273242.]
• Surgical management of brain abscess Mainstay = burr hole Larger, multiloculated, or recurrent = craniotomy
• Patients with brain abscess and massive cerebral oedema on CT should also be given IV dexamethasone
• Encephalitis is most commonly caused by HSV-1 herpes simplex virus type 1
• HSV-1 is associated with temporal & frontal lobe encephalitis hence why it may present with aphasia (temporal)
• Viral encephalitis in neonates is more commonly caused by HSV-2 Acquired at the time of delivery (HSV-2 causes genital herpes in mother)
• Encephalitis often presents first with meningeal signs: fever, headache, neck stiffness, & vomiting followed by parenchymal signs: - AMS/confusion - Seizures - Dysphasia
• Encephalitis then progresses to parenchymal signs: AMS/confusion, seizures, & dysphasia
• Patients with encephalitis & cold sores may suggest an underlying cause by HSV-1
• Patients with encephalitis & parotid gland swelling may suggest an underlying cause of mumps
• Patients with encephalitis & hydrophobia, hallucinations, anxiety may suggest an underlying cause of Rabies
• Patients with encephalitis & travel history to rice fields in Asia may suggest an underlying cause of Japanese encephalitis virus Arbovirus
• What is the best investigation for suspected encephalitis? LP & CSF analysis; cells, protein, glucose & virology PCR **Unless ICP is raised ↑, do CT scan to rule this out You should NOT wait for cause to be known before starting treatment → ADMIT & give IV aciclovir. If it is meningitis, it does no harm. [Management of Suspected Viral Encephalitis in Adults. Association of British neurologists and British Infection Association National Guidelines. https://encephalitis.info/wp-content/uploads/2023/11/Management-of-Viral-Encephalitis-in-Adults.pdf]
• Herpes encephalitis presents with the following on CSF analysis: ↑ lymphocytes and RBCs normal glucose ↑ protein
• What investigation should be done prior to lumbar puncture for suspected encephalitis? CT scan; helps identify ↑ ICP and rule out space-occupying lesions, strokes, basilar fractures [Management of Suspected Viral Encephalitis in Adults. Association of British neurologists and British Infection Association National Guidelines. https://encephalitis.info/wp-content/uploads/2023/11/Management-of-Viral-Encephalitis-in-Adults.pdf]
• What is the management for encephalitis? Immediate IV aciclovir for 2-3 weeks (HSV cover) IV antibiotics (meningitis cover) Admit to ICU
• What factor best predicts the outcome in encephalitis? Early initiation of IV aciclovir; mortality is ~10-20% if treated promptly, ~70-80% if left untreated
• Essential tremor is a chronic neurological disorder characterised by a bilateral action tremor, most commonly in the hands & forearms, without other neurological deficits
• Essential tremors have a bimodal distribution in 20-40 year olds and >60 year olds Most frequently in older adults
• Does an essential tremor limit functional capacity? In some it can be severe and disruptive