NEUROLOGICAL MALFORMATIONS AND INFECTIONS Flashcards
What is hydrocephalus?
Enlargement of the cerebral ventricles, due to excessive accumulation of CSF.
How do we classify the causes of hydrocephlaus?
- malfomations that communicate with the sub-arachnoid space (extraventricular)
- those that do not (intraventricular)
What are the intraventicular causes of hydrocephalus?
Congenital malformations: - Aquaduct stenosis - Dandy-Walker syndrome (no cerebellar vermis - back of cerebellum, large 4th ventricle and cyst at base of skull) Intraventricular haemorrhage Ventriculitis Brain tumour
What are the extraventricular causes of hydrocephalus?
Subarachnoid haemorrhage
Tuberculous meningitis
Arnlod-Chiari malformation (displacement of the cerebellar tonsil through the foramen magnum)
What are the clinical features of hydrocephalus in an infant?
Disproportionately large head circumference
Rate of growth is excessive
Bulging of anterior fontanelle
Sutures become seperated
Prominent scalp veins
Eyes deviate inwards (setting-sun sign - late sign)
What are the clinical features of hydrocephalus in an older child?
Headache Vomiting Irritability Papilloedema Lethargy Abnormality of pupillary size and reaction Decerebrate/decorticate posturing
How is the diagnosis of hydrocephalus attained?
Imaging - USS if the anterior fontanelle is patent otherwise CT/MRI
How would one treat hydrocephalus?
What are the complications of the treatment?
Ventriculoperitoneal shunt
Infection and obstruction
What is craniosynostosis?
Premature fusion of cranial sutures
Which suture is most commonly involved in craniosynostosis and what shaped head does the affected patient end up with?
Sagittal
Long narrow skull
What are the three main types of neural tube defect?
Spina bifida occulta
Meningocele
Myelomeningocele
Where are most neural tubes found?
Lumbosacral region
What is an encephalocoele?
Extrusion of the brain and meninges through a midline skull defect
What is anencephaly?
The cranium and brain fail to develop (detected on antenatal ultrasound and termination is usually offered)
What is spina bifida occulta?
When the dorsal vertebral arch fails to fuse properly.
What are the clinical features to look for regarding spina bifida?
Overlying skin lesion
Tuft of hair
Small dermal sinus
Back pain on exertion in older children if it is mild and therefore picked up later
What is a meningocoele?
Failure of vertebral arch to fuse with added feature of smooth, intact skin covered cystic swelling is filled with CSF.
What is the prognosis of a meningocoele?
There is usually no neurological deficit or hydrocephalus and excision and closure is usually performed at 3 months. They are very rare.
What is a myelomeningocele?
This accounts for more than 90% of overt spina bifida. Again failure of vertebral arch to fuse but this time the lesion is open with both herniation of the cord and meninges. CSF leakage is common. Neurological deficits will always be present.
What are the neurological deficits seen in myelomeningocele?
Motor and sensory loss in the lower limbs
Neuropathic bladder and bowel control loss
Other than the neurological deficits, what other features are often seen in infants born with myelomeningoceles?
Arnold-Chiari malformations - extraventricular hydrocephalus caused by hernia of lower cerebellar tonsils through foramen magnum.
Scoliosis
How do you treat patients with myelomeningocele?
Surgery. This will prevent infection however, this can never reverse neurological deficits
What are the three bacteria that more commonly cause meningitis in neonates?
Group B streptoccocus
E. coli
Listeria monocytogenes
What are the main bacteria that cause meningitis in slightly older children?
N. meningitidis
S. pneumoniae
H. inluenzae type b
What viruses are commonly causative of viral meningitis?
Mumps
Enterovirus
EBV
What is the peak age for bacterial meningitis?
Under 5 years
What vaccines against meningitis causative bacteria are children now given?
Hib - H.influenzea type b
Men C - meningococcocus type C
What are the clinical features of bacterial meningitis?
Features can be very non-specific in younger infants:
Irritability Vomiting Poor feeding Fever Drowsiness
More specific later signs include:
Bulging fontanelle
Neck stiffness and photophobia in older children
Seizures: beware the child diagnosed with benign febrile seizures.
Non-blanching rash
How do you diagnose meningitis in children?
LP is diagnostic. Remember though that treatment must not be delayed for LP if meningitis is suspected.
What are the contraindications for performing an LP in a child with suspected meningitis?
High intracranial pressure
Coagulopathy
Septic shock
What are the signs of high intracranial pressure?
Papilloedema
Reduced consciousness
Focal neurological signs
How do we treat children for meningitis?
Broad spectrum antibiotics - ceftriaxone
Dexamethasone
What antibiotics would you use in an infant who was less than 3 months old in whom you suspected bacterial meningitis?
Cefotaxime AND amoxicillin
If you were a GP, how would you manage a febrile child with a non-blanching purpuric rash in the community? Give doses.
IV or IM Benzylpenicillin and immediate admission to hospital
Infant - 300 mg
1 - 10 years old - 600 mg
More than 10 years old - 1200 mg
Bacterial meningitis can kill in hours and early administration of antibiotics has been shown to reduce mortality
Other than treating the child for meningitis, what must you as the doctor?
Notifiable disease
Treat household contacts with antibiotics
What are the acute complications of meningitis?
Cerebral oedema
Seizures
Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Hearing loss is common and should be checked post recovery
What are the 3 most common causes of acute encephalitis in the UK?
Herpes simplex virus 1 and 2
Enterovirus
Varicella
What are the clinical features of acute encephalitis?
Early non-specific symptoms such as:
Fever
Headache
Vomiting
Followed by:
Altered consciousness
Seizures
How do you manage someone with the clinical features consistent with encephalitis?
High dose aciclovir
Admit to ITU
Seizure control and monitoring for raised intracranial pressure
What investigations might you do to help you with your diagnosis of acute encephalitis?
EEG
MRI - characteristic temporal lobe abnormalities
LP
