Neurology








After reading this chapter you should be able to:




  • understand and request suitable neurophysiological and neuroimaging studies.



  • assess and diagnose abnormalities in skull development.



  • investigate and manage headache.



  • assess, diagnose, investigate and manage seizure disorders.



  • assess, diagnose and manage muscular dystrophies, neuropathies, myopathies and myalgia.



  • assess, diagnose and manage ataxia.



  • assess, diagnose and manage stroke.




Neurological investigations


Neurophysiological investigations


Electroencephalogram (EEG)


EEG is used in the assessment and diagnosis of seizure disorders, encephalopathy and sleep disorders.The commonly used EEG investigations are:




  • standard awake EEG—usually requested after a second seizure but may also be considered after a cluster of seizures, focal seizures or a prolonged seizure. The interpretation should recognise that the interictal EEG may be normal in a child with epilepsy and abnormal in children who do not have epilepsy



  • sleep-deprived EEG—useful in the diagnosis of conditions where abnormalities are likely to be seen in sleep such as epileptic spasms with hypsarrhythmia or structural focal epilepsy



  • awake EEG with photic stimulation and hyperventilation—useful in diagnosing childhood absence epilepsy



  • ambulatory EEG—used to capture suspected seizures where there is significant uncertainty about the diagnosis of epilepsy after standard awake and sleep EEG



  • video telemetry—requires an inpatient stay and uses multiple-angle video recording to characterise the seizure and correlate it with the parallel EEG recording



Cerebral function monitoring


The most common application is in the NICU to assess babies with suspected hypoxic ischaemic encephalopathy where it is used to detect electrical seizures and suppressed brain activity.


In PICU, cerebral function monitoring may be used in children with status epilepticus or acquired brain injury, as seizures cannot be detected clinically if the child is paralysed and ventilated.


Nerve conduction studies and electromyography


These investigations help define the pathophysiological process seen with neuromuscular disorders such as Guillain Barre syndrome. They can assess function at different locations on the neural conduction pathway. These are:




  • anterior horn cell—spinal muscular atrophy



  • peripheral nerves—Guillian-Barre syndrome



  • neuromuscular junction—acquired and congenital myasthenia



  • muscle—congenital myopathies or muscular dystrophies



Neuroimaging


Cranial ultrasound


Indications




  • screening for intraventricular haemorrhage in preterm babies



  • measuring the ventricular index in hydrocephalus to guide intervention



  • ischaemic injury in the basal ganglia in a term neonate



  • detecting arterial ischaemic stroke



  • used to detect large structural abnormalities such as agenesis of the corpus callosum



  • cerebral calcifications in congenital infection (CMV or toxoplasmosis)



Computed tomography (CT) imaging


CT is commonly used in neurological emergencies as it has a shorter scan time and is better tolerated in children than is MRI. There is, however, a radiation exposure.


Indications:




  • traumatic brain injury looking for acute subdural, extradural, parenchymal and subarachnoid bleeds and skull fractures. Cerebral oedema and features of raised intracranial pressure can be seen on CT



  • abnormal skull shape where craniosynostosis is suspected as the images allow 3D reconstructions



  • acute stroke to identify occlusion of a cerebral artery by thrombus



  • ventriculoperitoneal shunt blockage



Magnetic resonance imaging (MRI)


MRI has the advantage of not using ionising radiation and has the ability to use a number of differing sequences to identify a wide range of pathological abnormalities. However, in younger children, it may not be tolerated without sedation or general anaesthesia due to longer scanning times, claustrophobia and the noise within the magnet.


Indications:




  • suspected spinal emergencies—spinal cord compression and transverse myelitis



  • neurological emergencies—encephalitis or demyelinating conditions



  • tumour and abscess assessment



  • epilepsy and developmental impairment or regression



The most common sequences are T1 and T2 weighted images, where water appears bright on T2 sequences but dark on T1 sequences. Diffusion weighted images help to identify areas of cytotoxic damage to the brain, for instance an acute arterial ischemic stroke.


Magnetic resonance spectroscopy acquires signal from a single localised area and measures the concentration and physical properties of cell metabolites such as choline (elevated in some tumours) or lactate (elevated in hypoxic ischaemic injury and stroke).


Abnormal head shape


Microcephaly


Microcephaly is generally defined as an occipito-frontal head circumference (OFC) greater than 3 standard deviations below the mean for the age and sex. Causes include:




  • hypoxic ischaemic insult at birth



  • congenital infection



  • foetal alcohol syndrome



  • genetic disorders



  • structural brain abnormalities



Macrocephaly


Macrocephaly is an OFC greater than 3 standard deviations above the mean for the age and sex. Causes include:




  • familial—important to measure and plot parental OFC



  • hydrocephalus



  • neurogenetic conditions including neurometabolic and neurocutaneous disorders



Plagiocephaly


The most common cause of abnormal head shape in infants is positional plagiocephaly, which results from a baby lying on the back for long periods with the head on one side. If development and neurological examination is normal, then no investigations are necessary. Parents may be advised to implement supervised ‘tummy time’ to allow time without pressure on the skull bones. Preterm babies classically have a scaphocephalic head shape for similar reasons.


Craniosynostosis


Craniosynostosis describes an abnormal and premature fusion of the skull bones and may involve one or multiple sutures ( Figure 26.1 ). Multiple-suture craniosynostosis is more likely to be associated with underlying genetic conditions such as Crouzon, Apert or Pfeiffer syndrome.




Fig. 26.1


Premature fusion of cranial sutures leading to abnormal shapes of skull

Image used with permission from Principles of Neurological Surgery. Ed. Kitchen ND et al. 4th edition. Chapter 9 . Tushar Jha R et al. Elsevier Inc.


Abnormal fusion of the skull sutures may result in scaphocephaly (fusion of the sagittal suture), trigonocephaly (metopic suture synostosis), nonpositional plagiocephaly (unilateral coronal synostosis) and bilateral lambdoid synostosis.


Multiple suture craniosynostosis is more likely to result in complications such as raised intracranial pressure, and these children may require neurosurgical intervention at a recognised craniofacial centre.


Epilepsy


Epilepsy is a clinical diagnosis that is usually based on the description or video recording of two unprovoked seizures which are 24 hours apart. Seizures are described as either focal or generalised and they may be associated with impairment of awareness (dyscognitive seizures) or preserved awareness. Motor manifestations include tonic stiffening, clonic jerking, dystonic posturing, loss of tone, myoclonus and forced head version. Nonmotor manifestations may include emotional disturbance, visual hallucinations, loss of speech, sensory changes or aura.


Epilepsy syndromes are determined by age of onset of the seizures, ictal manifestations and neurodevelopment of a child in the context of the abnormalities present on an electroencephalogram (EEG). Reaching an electroclinical diagnosis is crucial in helping to guide treatment and determine the aetiology and prognosis.


Neonatal seizures


These are described in Chapter 2 Neonatology.


Epilepsies of infancy


Epilepsies presenting beyond the neonatal period in infancy are more likely to result from a monogenic disorder or a structural brain malformation rather a postnatal acquired insult.


Many neurogenetic conditions associated with early developmental impairment may present or be associated with epilepsy. There may be characteristic dysmorphic features that will help point towards a specific diagnosis such as Rett’s syndrome or Angelman syndrome.


Epileptic spasms (ES)


These were previously known as infantile spasms, and they tend to present between 3 and 24 months of life but can be present from the neonatal period. They are characterised by recurrent brief, stereotypical movements occurring in clusters, with extension or flexion of both arms and sudden flexion of the head. The majority of infants presenting with ES will ultimately develop intellectual and motor disability.


The EEG in ES shows a chaotic background activity known as hypsarrhythmia ( Figure 26.2 ) that is evident particularly during a period of sleep. West syndrome describes the characteristic triad of the characteristic epileptic spasms, developmental regression and hypsarrhythmia on EEG. Epileptic spasms are also associated with many conditions including tuberous sclerosis where cortical tubers are the epileptogenic foci.




Fig. 26.2


EEG of 3-year-old boy with tuberous sclerosis showing hypsarrhythmia.

Image used with permission Metabolic Epilepsy: An update. Nicita F et al. Jap Soc Ch Neurol. 2013: 35.9


Treatment of epileptic spasms usually involves the combination of steroids and vigabatrin, although in tuberous sclerosis treatment is initially with vigabatrin alone. The aim of treatment is to control the epileptic encephalopathy and so improve the developmental potential of the child.


Epilepsies in young children


Childhood absence epilepsy


Typically presents between 4–8 years of age with multiple, abrupt-onset absences lasting 20–30 seconds. There may be eyelid flickering, head deviation, subtle lip twitching or hand automatisms. Seizures can be induced by hyperventilation. The EEG will show the typical pattern of three per second spike and wave activity ( Figure 26.3 ). Treatment is with either ethosuximide or sodium valproate and most children respond well.




Fig. 26.3


EEG of 3-year-old boy with absence seizures showing 3 per second spike and wave activity.

Image used with permission from Pädiatrie hoch2. Ed. Muntau AC and Driemeyer J. Chapter 19 . Elsevier GmbH.


Myoclonic atonic and myoclonic absence epilepsy


The condition presents in the preschool years and differs from absence epilepsy by the presence of myoclonic jerks and atonic head drops accompanying the absence episode. The seizures are typically more refractory to treatment, and developmental impairment is common. Batten’s disease, a neurodegenerative lysosomal storage disease, may present in a child with developmental regression associated with myoclonic seizures. Treatment with carbamazepine and phenytoin may make absence epilepsy worse.


Childhood epilepsy with centrotemporal spikes


This condition was previously known as benign Rolandic epilepsy and presents with focal, often nocturnal, seizures sometimes with secondary generalisation. The focal seizures are typically associated with speech arrest and facial twitching. Many children will only have one or two seizures and so treatment may not be required.


Lennox Gastaut syndrome


A condition that is commonly associated with drug refractory epilepsy as well as early developmental impairment. The hallmark seizure types are nocturnal tonic seizures although atypical absences, drop attacks, myoclonic jerks and focal seizures can be seen. The most common cause is a structural brain abnormality such as hypoxic ischaemic injury from the neonatal period. Treatment of this condition is difficult and usually involves the use of multiple antiepileptic medications as well as nondrug options such as the ketogenic diet, vagal nerve stimulation and, in suitable children, epilepsy surgery.


Epilepsies of adolescence


Juvenile absence epilepsy


Patients present normally after 8 years of age, and the EEG will often demonstrate photosensitivity along with a polyspike and wave pattern. Most will go on to have generalised convulsive seizures that may persist into adulthood, and so treatment with a broad-spectrum anticonvulsant such as levetiracetam, lamotrigine or sodium valproate is usually recommended.


Juvenile myoclonic epilepsy


This may present initially with absence seizures followed by the onset of myoclonic jerks and generalised tonic clonic seizures in the later teenage years. Lifelong treatment with sodium valproate, lamotrigine or levetiracetam is recommended whilst carbamazepine may make seizure control worse.


Structural focal epilepsies (temporal, frontal and occipital lobe epilepsy)


These result from areas of structurally abnormal brain tissue such as an area of cortical dysplasia, and the most common areas of abnormality are the temporal lobes followed by the frontal lobes.


Temporal lobe epilepsy is most typically associated with mesial temporal sclerosis where there may have been a history of prior febrile convulsions in infancy. Temporal lobe seizures may manifest in an aura such as a feeling or fear, déjà vu or jamais vu (never seen) or a rising epigastric sensation prior to the onset of a focal motor seizure which may become generalised.


Frontal lobe seizures are often nocturnal and frequently present a diagnostic challenge. They may manifest in a dystonic posturing, salivation and rapid thrashing movements (hyper motor seizures), and there are often several short seizures in a night.


Occipital lobe seizures may manifest in multicoloured visual hallucinations particularly shapes such as circles or flashes.


Anticonvulsant treatment can be effective, but epilepsy surgery should be considered early in children under 2 years and in those children where seizures do not respond to two appropriately chosen antiepileptics.


Outcomes


Around 50% to 60% of children and young people with epilepsy will have complete seizure remission during their childhood. The presence of ongoing seizures and intellectual disability are associated with worse social outcomes in adulthood for children with epilepsy.



Table 26.1

Epilepsy syndromes and commonly used antiepileptic drugs




































Epilepsy syndrome Commonly used AEDs Common AEDs which may make epilepsy worse
neonatal acute seizures levetiracetam, phenobarbitone
infantile spasms prednisolone
vigabatrin
child absence epilepsy sodium valproate
ethosuximide
carbamazepine
benign focal epilepsies of childhood levetiracetam
sodium valproate
carbamazepine
Lennox Gastaut syndrome sodium valproate
lamotrigine
clobazam
carbamazepine, phenobarbitone
structural focal epilepsy carbamazepine
lamotrigine
levetiracetam
juvenile absence epilepsy
juvenile myoclonic epilepsy
sodium valproate
levetiracetam
lamotrigine
carbamazepine

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Jun 18, 2022 | Posted by in PEDIATRICS | Comments Off on Neurology
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