Neurology Flashcards
Stages of neural development
Dorsal induction Ventral induction Neuronal proliferation Neuronal migration Cortical organisation Myelination
Myelination on MRI
Pattern:
- Unmyelinated brain has more water than fat content –> relatively dark on T1 and brighter on T2 compared to cortex
- With myelination, this pattern reverses
- Spreads from central to peripheral, posterior to anterior
T1 precedes T2:
- T1 completed by 1 year
- T2 completed by 2 years
Subdural haematoma
Tearing of bridging VEINS (venous bleeding) –> bleeding into potential space
- Crescentic
- Cross sutures
- Follows dural folds
- Outlines subarachnoid space
- Most consistent finding with abusive head injury
Epidural haematoma
Arterial bleed secondary to skull fracture
- Lens-shaped bleeding from stripping of dura from the skull
- Bound by sutures
Subarachnoid haemorrhage
- Extends into sulci and fissures
2. Best seen on T2* or FLAIR MRI
Holoprosencephaly
Failure of embryonic forebrain to separate –> fusion of e.g. frontal lobes
*Abnormality of ventral induction i.e. separation
Lissencephaly
with agyria/pachygyria complex
Smooth brain with increased cortical thickness, cell-sparse layer
Agyria = absence of gyri; pachygyria = thickened cortex
DCX = more severe anteriorly; LIS1 = more severe posteriorly
*Abnormality of neuronal migration
Polymicrogyria
Lots of small gyri = appears nodular
- Can be focal or bilateral
- Overfolded cortex with false impression of cortical thickening
- Associated abnormal deep or elongated sulci
- Any disruptive process to cortex will be lined by polymicrogyria
Schizencephaly
Full-thickness cleft through hemisphere
- Often lined by polymicrogyria
- Open or closed lip
Causes:
- Intrauterine neuro insult (~20wk): CMV infection, HIE
- Genetic: COL4A1
Heterotopia
Abnormal position of grey matter
*Abnormality of neuronal migration
Focal cortical dysplasia
Subtle focal dysplastic cortex, can manifest as “blurring” of cortex (subtle finding)
*Accelerated myelination
EEG: normal background activity
- Alpha rhythm:
- 8-12Hz - usually gradually increases with age; infancy 6-8Hz, 3yrs >8Hz
- Prominent posteriorly on eye closure - Theta waves:
- 4-8Hz
- Normal in children up to 13yrs and in drowsiness/sleep - Delta waves:
- <4Hz
- Normal in deep sleep (stage 2 and 3)
- Focal finding: can be assoc with structural pathology
- Generalised finding: diffuse encephalopathy - Beta waves:
- >13Hz
- Often prominent in presence of drugs (barbituates, BZD)
- Commonly seen in frontal region
EEG: epileptiform discharges
- Sharply contoured discharges
- Sharp waves <200ms
- Spikes <70ms
- No difference in biological significance between 2 forms - Multiple phases
- Clearly disrupts background activity
- After-coming slow wave
- Sensible electrical field distribution
Genes associated with Charcot-Marie-Tooth Disease Type 1
Autosomal dominant inheritance: CMT1A - PMP22 (17p11) CMT1B - Po (1q22) CMT1C - LITAF (16p13) CMT1D - EGR2 (10q21)
Genes associated with Charcot-Marie-Tooth Disease Type 2 and Type 3
CMT2 - MFN2 (autosomal dominant)
CMT3 - PMP22 (point mutations) - 8q23, 17p11, 10q21
Risk factors for CP
Male
Prematurity - 43% of pts with CP are prem
Low birth weight - 43%
Multiple birth (twins/triplets) - 11%
Birth asphyxia/adverse intrapartum events - 10%
Infection in late pregnancy - sig. RF for term neonates
Previous/multiple MCs - ?genetic, clotting disorders
APGAR score at 1min
Breech position
Maternal smoking, illicit substance use
Genetic component
Strongest predictor of mortality in CP
Profound intellectual disability
- 22% die by 5yrs
- 50% die by 18yrs
GMFCS Level 1
- Can walk independently on all surfaces
- Can run and jump, but speed, co-ordination and balance are reduced
- 35% of CPs
GMFCS Level 2
Walks independently, but:
- Difficulty walking on uneven surfaces, inclines, crowded places
- 24% of CPs
GMFCS Level 3
- Requires assistive mobility devices, orthoses for walking
- Wheelchair required for long distances
- Sits independently, has independent floor mobility
- 12% of CPs
GMFCS Level 4
- Uses power mobility outdoors and in community
- Supported sitting function
- Requires assistance with standing transfers
- Mobility is limited
- 13% of CPs
GMFCS Level 5
- No independent mobility
- Poor antigravity head and trunk postures
- Require tilt in space and seating systems
- 15% of CPs
Selective dorsal rhizotomy
Laminectomy L1-S1 –> dorsal nerve root transection
- 20-30% sensory nerve rootlets from L2-S1
To reduce lower limb spasticity
Irreversible
Indications for selective dorsal rhizotomy
Spastic diplegia: GMFCS II to III
Moderate to severe spasticity
Limited contractures
Motivated patients and parents: intense functional training over 1-2yrs follows
Goal: gait kinematics improvement, spasticity management
- No supporting evidence that it improves function (i.e. general activities) and participation
*Does NOT prevent further need for orthopaedic surgery