The clinical presentation of the boy suggests the involvement of the right frontal lobe.Psychiatric or behavioural disturbances secondary to frontal lobe lesions exhibit lateralisation. The lesions of the left hemisphere are associated with depression, especially if the lesion involves the dorsolateral portion of the prefrontal cortex. Whereas, lesions of the right hemisphere are associated with impulsivity, disinhibition, and aggression, as it is the case with the child in question.Presenting symptoms of lobar dysfunctions:- Frontal lobe: Contralateral hemiplegia, impaired problem solving, disinhibition, and lack of initiative. Broca’s aphasia and agraphia suggest the involvement of the dominant hemisphere.- Temporal lobe: Wernicke’s aphasia (dominant hemisphere involvement), homonymous upper quadrantanopia and auditory agnosia (non-dominant hemisphere involvement).- Parietal lobe: Anosognosia, dressing apraxia, spatial neglect and constructional apraxia are observed when the non-dominant hemisphere is involved. Gerstmann’s syndrome is observed when the dominant hemisphere is involved.- Occipital lobe: Visual agnosia, visual illusions and contralateral homonymous hemianopia.

Mild learning disabilities indicates an IQ = 50-70, or mental age of 9-12 years
Moderate learning disabilities indicates an IQ = 35-49, or mental age of 6-9 years
Severe learning disabilities indicates an IQ = 20-34, or mental age of 3-6 years
Profound learning disabilities indicates an IQ = 20, or mental age of less than 3 years
Average IQ is 100. The arbitrary cut-off to indicate learning disabilities is 70.

The sympathetic chain lies posterior to the parietal pleura. During a thorascopic sympathectomy, this structure will have to be divided. The intercostal vessels lie posteriorly. They may be damaged with troublesome bleeding but otherwise are best left alone as the deliberate division will not improve surgical access.The sympathetic nervous system:The cell bodies of the preganglionic efferent neurones lie in the lateral horn of the grey matter of the spinal cord in the thoracolumbar regions.The preganglionic efferents leave the spinal cord at levels T1-L2. These pass to the sympathetic chain.Lateral branches of the sympathetic chain connect it to every spinal nerve. These postganglionic nerves will pass to structures that receive sympathetic innervation at the periphery.Sympathetic chains:These lie on the vertebral column and run from the base of the skull to the coccyx.Clinical correlation:Interruption of the head and neck supply of the sympathetic nerves will result in an ipsilateral Horner’s syndrome.For the treatment of hyperhidrosis, the sympathetic denervation can be achieved by removing the second and third thoracic ganglia with their rami. Removal of T1 will cause a Horner’s syndrome and is therefore not performed.In patients with vascular disease of the lower limbs, lumbar sympathectomy may be performed, either radiologically or (more rarely now) surgically. The ganglia of L2 and below are disrupted. Care should be taken to preserve the L1 ganglion. If it is removed in male patients, ejaculation may be compromised.

The most probable cause for the patient’s presenting symptoms is encephalitis secondary to measles infection.Encephalitis:Encephalitis occurs in 1 per 1000 measles cases. It usually presents within 1–14 days of the rash, usually day 5. It may present with fever, headache, vomiting, stiff neck, meningeal irritation, drowsiness, seizures, reduced consciousness| 15% will have neurological sequelae| 10% mortality.Other options:- Acute disseminated encephalomyelitis occurs in 1 per 1000 measles cases. It is thought to be a postinfectious immune response. Clinical manifestations include fever, headache, neck stiffness, seizures and mental status changes. It could fit this presentation although it tends to present in the recovery phase of measles infection, typically two weeks after the exanthem. In contrast, encephalitis tends to occur within a few days of the rash.- The history is not that of a typical febrile seizure as it lasted >15 minutes. He has also not recovered consciousness at 4 hours. The diazepam should have been eliminated within 4 hours and so should no longer be contributing to his reduced level of consciousness. Also, the history states the recent diagnosis of measles, and so complications of measles should be considered.- Intracranial bleed secondary to thrombocytopenia: Measles is not known to cause thrombocytopenia.- Subacute sclerosing panencephalitis (also known as Dawson’s encephalitis): This is an extremely rare complication of measles. It is a progressive degenerative disease of the central nervous system that occurs 7–10 years after a measles infection. The treatment for SSPE is mainly intraventricular interferon therapy through an Ommaya reservoir. The prognosis is poor, and it is usually fatal.

Non Epileptic attack disorder, also known as psychogenic non epileptic seizures, is a condition characterised by episodes of abnormal movement and behaviours that resemble seizures , but are not caused by electrical activity changes in the brain. It is believed that the disorder is caused by the brain’s response to overwhelming or stressful situations. In Jamila’s case, triggering conditions for her episodes may have been the absence of her mother, and the stress of her upcoming examinations. A diagnosis of generalised epilepsy is unlikely because this would require abnormal movement in all 4 limbs during an episode and a longer period of semi consciousness after. Cataplexy can also be ruled out as it does not involve a loss of consciousness which we see in Jamila’s case. Vasovagal syncope does not correspond with the history as there was no evidence of simultaneous collapse and responsiveness coupled with colour change and near spontaneous recovery when supine. A complex partial seizure may be possible in Jamila’s case, however the history of long duration, her eyes being tightly shut and the differences in presentation between the two episodes makes it less likely.

Vagus nerve lesions will affect the gag reflex since the pharyngeal muscles are innervated by it.The vagal nerve (10th cranial nerve ) is a mixed nerve carrying motor efferents and sensory afferents. The nerve conducts five distinct qualities, which are carried along general visceral efferent fibres (parasympathetic innervation of pharyngeal, laryngeal, bronchial, and gastrointestinal mucosa), general visceral afferent fibres (sensory information from the thoracic and abdominal viscera, the aortic body, aortic arch), special visceral afferent fibres (carry the taste of the epiglottal region), general somatic afferent fibres (carry sensation from the external auditory meatus, outer tympanic membrane, back of the ear, part of meninges, pharynx), and along special visceral efferent fibres, which innervate skeletal muscles of the pharynx and larynx. Skeletal muscles innervated by the vagal nerve include the cricothyroid, levator veli palatini, salpingopharyngeus, palatoglossal, palatopharyngeus pharyngeal constrictor, and the laryngeal muscles (except cricothyroid). Innervation of these muscles is involved during speech or opening of the larynx during breathing. Efferent parasympathetic fibres control heart rate, peristalsis, and sweating. Stimulation of the efferent parasympathetic fibres lowers heart rate or blood pressure. 80–90% of the vagal fibres are afferent, only 10–20% are efferent fibresPhysical exam of the 10th cranial nerve includes eliciting the gag reflex (The gag reflex involves a brisk and brief elevation of the soft palate and bilateral contraction of pharyngeal muscles evoked by touching the posterior pharyngeal wall.), to look if the uvula is deviated from the side of the lesion, if there is failure of palate elevation upon phonation, and evaluation of speech impairment.In case of bilateral vagal nerve lesions, heart rate and breath rate may be increased. The somatic sensory function can be assessed by testing the sensibility of the external auditory meatus.

Bilirubin encephalopathy (BE), also known as kernicterus is a preventable complication of neonatal jaundice. Bilirubin deposits in the basal ganglia, hippocampus, geniculate bodies and cranial nerve nuclei, exerting direct neurotoxic effects and causing mass-destruction of neurons by apoptosis and necrosis.The clinical features of this diagnosis have been well described and can be divided into 3 stages:Phase 1 (first few days of life): Decreased alertness, hypotonia, and poor feeding are the typical signs. Obviously, these are quite nonspecific and could easily be indicative of a multitude of neonatal abnormalities. A high index of suspicion of possible BIND at this stage that leads to prompt intervention can halt the progression of the illness, significantly minimizing long-term sequelae. Of note, a seizure is not typically associated with acute bilirubin encephalopathy.Phase 2 (variable onset and duration): Hypertonia of the extensor muscles is a typical sign. Patients present clinically with retrocollis (backward arching of the neck), opisthotonos (backward arching of the back), or both. Infants who progress to this phase develop long-term neurologic deficits. Phase 3 (infants aged >1 wk): Hypotonia is a typical sign.

The trigeminal nerve is responsible for the sensory innervation of the head, and the muscles of mastication. The nerve is divided into three branches, the ophthalmic nerve (V1) the mandibular nerve (V2) and the maxillary nerve (V3) which all exit the skull through their respective foramina. An easy way to remember these foramina is with the following mnemonic:Standing Room Only, for V1-V3 respectivelyV1- Superior orbital FissureV2- foramen RotundumV3 foramen Ovale

Clinical diagnosis of neurofibromatosis type 1 requires the presence of at least 2 of 7 criteria to confirm the presence of neurofibromatosis, type 1. Many of these signs do not appear until later childhood or adolescence, and thus confirming the diagnosis often is delayed despite a suspicion of NF1. The 7 clinical criteria used to diagnose NF1 are as follows:- Six or more café-au-lait spots or hyperpigmented macules greater than 5 mm in diameter in prepubertal children and greater than 15 mm postpubertal- Axillary or inguinal freckles (>2) – Two or more typical neurofibromas or one plexiform neurofibroma- Optic nerve glioma- Two or more iris hamartomas (Lisch nodules), often identified only through slit-lamp examination by an ophthalmologist- Sphenoid dysplasia or typical long-bone abnormalities such as pseudarthrosis- A first-degree relative (e.g., mother, father, sister, brother) with NF1

The blood-brain barrier (BBB) is a term used to describe the unique properties of the microvasculature of the central nervous system (CNS). CNS vessels are continuous nonfenestrated vessels, but also contain a series of additional properties that allow them to tightly regulate the movement of molecules, ions, and cells between the blood and the CNS.Blood vessels are made up of two main cell types: Endothelial Cells (ECs) that form the walls of the blood vessels, and mural cells that sit on the abluminal surface of the EC layer. The properties of the BBB are largely manifested within the ECs, but are induced and maintained by critical interactions with mural cells, immune cells, glial cells, and neural cells, which interact in the neurovascular unit.Astrocytes are a major glial cell type, which extends polarized cellular processes that ensheath either neuronal processes or blood vessels.This includes regulating the contraction/dilation of vascular smooth muscle cells surrounding arterioles as well as PCs surrounding capillaries. Astrocytes have been identified as important mediators of BBB formation and function because of the ability of purified astrocytes to induce barrier properties.

The patient’s clinical presentation is highly suggestive of Charcot–Marie–Tooth syndrome.It is a hereditary sensory and motor neuropathy. It is also the commonest cause of inherited peripheral neuropathy. The lower motor neuron signs are usually mild in childhood, the age of onset is very variable, and the distal weakness can take years to progress. It is not fatal and does not affect the normal life expectancy.

The central nervous system comprises of two types of cells| neurons and neuroglial cells. Glial cells are the support cells that serve a number of important functions. Three types of neuroglia comprise the mature nervous system, which are ependymal cells, microglia, and macroglia. The macroglia are of two types oligodendrocytes and astrocytes. Microglia are the neuroglial cells that serve the function of phagocytosis since they are derived from the hematopoietic stem cells and share properties with tissue macrophages. They remove the cellular debris from the site of injury or normal cellular turnover by performing scavenger function.

Autism is a neurodevelopmental disorder characterized by difficulties with social interaction, language delays, and some repetitive behaviours. Autism may be associated with some dysmorphic facial features, including macrocephaly, which denotes an abnormally large head. Macrocephaly is usually most observable during early childhood. The other features mentioned are not found to be associated with autism.

The spinal cord ends at L3 in the new-bornmigrates cephalad during childhood to end at L1 – L2 and reaches adult size by the age of 10.

Lamotrigine does not significantly increase risk of birth defects during pregnancy.

Hyperkinetic Gait is seen with certain basal ganglia disorders including Sydenham’s chorea, Huntington’s Disease and other forms of chorea, athetosis or dystonia. The patient will display irregular, jerky, involuntary movements in all extremities. Walking may accentuate their baseline movement disorder.

The clinical presentation and way the boy ‘climbs up’ his legs to get up from a supine position (Gowers’ sign) suggests proximal muscle weakness secondary to dermatomyositis.Dermatomyositis is an inflammatory myopathy that typically presents between the ages of five years and ten years. The onset is insidious, and the proximal muscle weakness and raised creatine kinase might be mistaken for muscular dystrophy. However, the systemic illness and rash are characteristic features of the condition.

Nissl body is a neuron-specific cellular structure. It is composed of rough endoplasmic reticulum and fine granules. The rough endoplasmic reticulum contains free ribosomes, and are the hub of protein synthesis. When these substances are exposed to a cresyl violet solution, they show selective-staining by turning purple-blue. In pathologic processes, they may undergo chromatolysis.

Injuries to the peroneal nerve can cause numbness, tingling, pain, weakness and foot drop. The branches of the common peroneal nerve innervate and control the muscles in the legs that lift the ankle and toes upward (dorsi flexion).

Acoustic neuroma/vestibular schwannoma is a benign slow-growing tumour. The clinical picture of the child suggests neurofibromatosis type 1 (NF1), with cafe-au-lait spots and axillary and inguinal freckling.

The lateral spinothalamic tracts carry pain and temperature sensations from the peripheries to the central nervous system.Note:The spinothalamic tract transmits impulses from receptors which measure crude touch, pain and temperature. The spinothalamic tract comprises the lateral and anterior spinothalamic tracts.The former typically transmits pain and temperature while the latter transmits crude touch and pressure. Neurones transmitting these signals will usually ascend by one or two vertebral levels in the Lissauer tract before decussating in the spinal cord itself. Neurones then pass rostrally in the cord to connect at the thalamus.

The most important test recommended among the given options is the measurement of creatine kinase levels.The child presents with a gross motor developmental delay, and multiple investigations can be undertaken to confirm the diagnosis. However, the clinching point in the given clinical scenario is the presence of a positive Gower’s sign.Gower’s sign is an excellent screening test for muscle weakness, which is typically observed as an early clinical feature of Duchenne muscular dystrophy (DMD).Creatinine kinase measurement is an easy and rapid test to aid in the diagnosis. Early diagnosis has significant implications not only for the child but for the family, particularly for genetic counselling. DMD is an X-linked recessive disorder, with an abnormal gene at the X chromosome at the Xp21 locus. It is a progressive degenerative muscular condition where muscle fibres are replaced by fat and fibrosis (i.e., become dystrophic).

Fragile X syndrome is a genetic syndrome associated with neuro-developmental problems such as learning disabilities and cognitive impairment, with many affected children having mild to moderate intellectual disability. About a third of children have features of autism spectrum disorder and ADHD which affects their communication skills and social interactions. As such, affected individuals usually have delayed speech development and poor nonverbal skills such as gaze aversion. Symptoms tend to worsen with age into adolescence as the demands on their intellect becomes greater. Pre-mutation carriers, who posses smaller genetic repeat expansions, have been found to be associated with some neurodevelopment and other medical problems.

Broca’s area is usually supplied by branches from the middle cerebral artery and thus will be spared when the anterior cerebral artery is occluded.Note:The two internal carotid arteries and two vertebral arteries form an anastomosis known as the Circle of Willis on the inferior surface of the brain. Each half of the circle is formed by:1. Anterior communicating artery2. Anterior cerebral artery3. Internal carotid artery4. Posterior communicating artery5. Posterior cerebral arteries and the termination of the basilar arteryThe circle and its branches supply the corpus striatum, internal capsule, diencephalon and midbrain.

Tension headache presents with pain that is pressing or tightening in quality, mild or moderate, and located bilaterally. It usually does not get worse with activities and may last from minutes to weeks.

Benign neonatal sleep myoclonus is a condition characterised by neonatal onset myoclonic jerks during NREM. Characteristic for this disorder is the absence of electroencephalographic findings.

Juvenile myoclonic epilepsy is an epilepsy syndrome characterized by myoclonic jerks, generalized tonic-clonic seizures (GTCSs), and sometimes, absence seizures. The seizures of juvenile myoclonic epilepsy often occur when people first awaken in the morning. Seizures can be triggered by lack of sleep, extreme fatigue, stress, or alcohol consumption. Onset typically occurs around adolescence in otherwise healthy children. The causes of juvenile myoclonic epilepsy are very complex and not completely understood. Mutations in one of several genes, including the GABRA1 and the EFHC1 genes, can cause or increase susceptibility to this condition. Although patients usually require lifelong treatment with anticonvulsants, their overall prognosis is generally good.

The most probable diagnosis in this patient would be Friedreich’s ataxia.Friedreich’s ataxia is also called spinocerebellar degeneration. It is an autosomal recessive condition. The onset of ataxia is around ten years of age. Intelligence is preserved. Cerebellar impairment, distal muscle weakness, pes cavus, hammer-toes and progressive kyphoscoliosis are present. Deep tendon reflexes are absent, particularly the ankle jerk. Loss of vibration and position sense occurs because of degeneration of the posterior columns. Hypertrophic cardiomyopathy can occur with progression to congestive cardiac failure.Other options:- Ataxia Telangiectasia: ataxia develops earlier, around two years of age, with loss of ambulation by adolescence. Nystagmus is present. Telangiectasia becomes evident by mid-childhood and is found on bulbar conjunctiva, over the bridge of the nose and on the ears. These children have an increased risk of developing lymphoreticular malignancies.- Abetalipoproteinemia: begins in childhood with steatorrhea and failure to thrive. Neurological symptoms appear in late childhood. These include ataxia, retinitis pigmentosa, peripheral neuritis, abnormalities in position and vibration sense, muscle weakness and mental retardation. Vitamin E is undetectable in serum in these patients.- Acute cerebellar ataxia: occurs in children of 1-3 years of age and is a diagnosis of exclusion. It often follows acute viral infections like varicella, coxsackievirus or echovirus by 2-3 weeks. It is an autoimmune response to a viral agent affecting the cerebellum. Prognosis is excellent with complete recovery present. Very small numbers have long term sequelae like ataxia, incoordination, speech disorder and behavioural problems.- Acute labyrinthitis: It is difficult to differentiate acute labyrinthitis from acute cerebellar ataxia in a toddler. It is associated with middle ear infections, vertigo and vomiting.

Benign intracranial hypertension is characterized by an elevation of the CSF pressure that is not caused by hydrocephalus or any space-occupying lesion. The cause is most likely the decreased absorption of CSF into the dural sinuses. The main symptoms are headache and visual abnormalities. It can lead to blindness if not managed on time. The most important risk factors for BIH are female gender and obesity. The causes of BIH include iron deficiency anaemia, sarcoidosis, Lyme disease, SLE, polycythaemia vera, chronic kidney disease, meningitis, and sleep apnoea.

Absence epilepsy is the most common type of generalized childhood epilepsies. It is mainly idiopathic, but 10-40% of the cases have a positive family history. It is characterized by frequent absence seizures and periods of unconsciousness. The hallmark of absence epilepsy on EEG is the bilaterally synchronous 2–4 Hz spike and wave discharges (SWDs). The average age of onset is around 4-8 years, being more prevalent among girls. Treatment resistance is not common.