Neuro - Arnold-Chiari, Ataxias, CJD, brain abscess and encephalitis Flashcards
What is an Arnold chiari malformation?
Arnold-Chiari malformation describes the downward displacement, or herniation, of the cerebellar tonsils through the foramen magnum. Malformations may be congenital or acquired through trauma.
Features
non-communicating hydrocephalus may develop as a result of obstruction of cerebrospinal fluid (CSF) outflow
headache
syringomyelia
What is ataxia telangiectasia?
Ataxia telangiectasia is an autosomal recessive disorder caused by a defect in the ATM gene which encodes for DNA repair enzymes. It is one of the inherited combined immunodeficiency disorders. It typically presents in early childhood with abnormal movements.
Name some features of ataxia telangiectasia
- Cerebellar ataxia
- Telangiectasia (spider angiomas)
- IgA deficiency resulting in recurrent chest infections
- 10% risk of developing malignancy, lymphoma or leukaemia, but also non-lymphoid tumours
What is Friedreich’s ataxia? Name some features
- Most common early-onset hereditary ataxia
- Autosomal recessive, trinucleotide repeat (GAA) on chromosome 9 (doesn’t demonstrate anticipation)
- Onset: 10-15 ya
Features
- Absent ankle jerks/extensor plantars
- Cerebellar ataxia
- Optic atrophy
- Spinocerebellar tract degeneration
What is Cretuzfeldt-Jakob disease? Name some features of this condition
- Rapidly progressive neurological condition caused by prion proteins. These proteins induce the formation of amyloid folds resulting in tightly packed beta-pleated sheets resistant to proteases.
- Features: rapid onset dementia, myoclonus
Name some investigations you would perform in CJD
- CSF is usually normal
- EEG: biphasic, high amplitude sharp waves (only in sporadic CJD)
- MRI: hyperintense signals in the basal ganglia and thalamus
Brain abscess: name some ways in which these occur
- Extension of sepsis from middle ear or sinuses
- Trauma
- Surgery to scalp
- Penetrating head injuries
- Embolic events: eg endocarditis
Brain abscess: describe the presenting symptoms
The presenting symptoms will depend upon the site of the abscess (those in critical areas e.g. motor cortex) will present earlier. Abscesses have a considerable mass effect in the brain and raised intracranial pressure is common.
- Headache: often dull, persistent
- Fever: may be absent and usually not the swinging pyrexia seen with abscesses at other sites
- Focal neurology: e.g. oculomotor nerve palsy or abducens nerve palsy secondary to raised intracranial pressure
- Other features consistent with raised intracranial pressure: nausea, papilloedema, seizures
What investigations and management would you perform for someone with a suspected brain abscess? O
-CT: visualisation of abscess
Management
-Surgery: a craniotomy is performed and the abscess cavity debrided —> the abscess may reform because the head is closed following abscess drainage.
-IV antibiotics: IV 3rd-generation cephalosporin + metronidazole,
intracranial pressure management: e.g. dexamethasone
What is encephalitis? Name some features of this condition
- Inflammation of the brain
- fever, headache, psychiatric symptoms, seizures, vomiting
- Focal features e.g. aphasia
- Peripheral lesions (e.g. cold sores) have no relation to presence of HSV encephalitis
Name some causes of encephalitis? Which lobes tend to be affected? How would you investigate a patient with suspected encephalitis?
- HSV-1: responsible for 95% of cases in adults (typically affects temporal and inferior frontal lobes)
- CSF: lymphocytosis, elevated protein
- PCR for HSV
- CT: medial temporal and inferior frontal changes (e.g. petechial haemorrhages) - normal in one-third of patients (MRI is better)
- EEG pattern: lateralised periodic discharges at 2 Hz
How would you manage someone with encephalitis?
-IV aciclovir should be started in all cases of suspected encephalitis
