57  Basic Neruroscience

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Published

June 9, 2026

57.1 Introduction

Understanding paediatric neurology begins with grasping the fundamentals of the nervous system’s anatomy and physiology. The nervous system in children is dynamic and continuously developing, exhibiting distinct features compared to that of adults.

  1. Structure and Development
    • The nervous system comprises the central nervous system (CNS)—brain and spinal cord—and the peripheral nervous system (PNS)—cranial and spinal nerves.
    • Neural tube development begins in the third week of gestation, giving rise to the brain and spinal cord.
    • Myelination, the process of forming the myelin sheath around neurons, continues from the prenatal stage into adolescence. In children, the degree of myelination affects neurological function and should be taken into consideration during assessments.
  2. Brain Regions and Functions
    • Cerebrum: Higher functions like cognition, voluntary movement, and perception.
    • Cerebellum: Coordination, balance, and motor control.
    • Brainstem: Regulates vital functions like respiration, heart rate, and consciousness.
    • Spinal cord: Conveys messages between the brain and the rest of the body.
  3. Peripheral Nervous System
    • Consists of motor, sensory, and autonomic nerves.
    • Motor neurons control muscle activity, while sensory neurons transmit information like pain, temperature, and proprioception.
    • Autonomic nerves regulate involuntary functions (e.g., heart rate, digestion).
  4. Neurotransmitters
    • Acetylcholine, dopamine, GABA, and glutamate play crucial roles in neural signalling.
    • Imbalances are implicated in various neurological disorders like epilepsy, movement disorders, and developmental conditions.

57.2 Pathological Processes in Neurology

Paediatric neurological diseases result from a variety of underlying mechanisms:

  1. Congenital Disorders
    • Neural tube defects (NTDs), e.g., spina bifida and anencephaly, due to folate deficiency in pregnancy. cy.
    • Cerebral palsy (CP): A group of permanent movement disorders from non-progressive disturbances in the developing foetal or infant brain.
  2. Genetic and Metabolic Disorders
    • Neurocutaneous syndromes: e.g., Tuberous Sclerosis and Neurofibromatosis.
    • Inborn errors of metabolism: Can cause neurodegeneration or developmental delay (e.g., phenylketonuria, Tay-Sachs disease).
  3. Infectious Causes
    • Meningitis, encephalitis, and brain abscesses are common in low-resource settings.
    • Causative agents include Neisseria meningitidis, Streptococcus pneumoniae, Herpes Simplex Virus, and Plasmodium falciparum (cerebral malaria).
  4. Inflammatory and Autoimmune Conditions
    • Acute disseminated encephalomyelitis (ADEM): Post-infectious or post-vaccination immune response.
    • Guillain-Barré Syndrome (GBS): Acute polyneuropathy causing weakness, often post-infection.
  5. Epilepsy and Seizure Disorders
    • Febrile seizures are common in Ghanaian children aged 6 months to 5 years.
    • Epilepsy can be idiopathic, structural, metabolic, or secondary to infection or trauma.
  6. Trauma
    • Head injury from road traffic accidents or falls is a leading cause of morbidity.
    • May result in skull fractures, intracranial haemorrhage, or brain oedema.
  7. Tumours
    • Paediatric CNS tumours include medulloblastoma, astrocytoma, and ependymoma.
    • Present with increased intracranial pressure, focal deficits, or seizures.

57.3 Neurological Signs and Symptoms in Children

Children may not accurately describe their symptoms, so observation and parental history are crucial.

  1. Seizures
    • Generalized (tonic-clonic, absence) or focal.
    • Observe the duration, type, postictal state, and presence of triggers (fever, sleep deprivation).
  2. Developmental Delay
    • Failure to achieve motor, cognitive, language, or social milestones.
    • Global developmental delay affects multiple domains.
  3. Headache
    • Can result from infection (meningitis), intracranial pressure, or tension.
    • Red flags: morning headache, vomiting, visual changes, altered consciousness.
  4. Ataxia and Gait Abnormalities
    • Unsteady gait or coordination problems can suggest cerebellar disease or vestibular dysfunction.
    • Sudden onset may indicate infection, tumor, or intoxication.
  5. Altered Consciousness
    • Ranges from drowsiness to coma.
    • Common causes: CNS infection, trauma, metabolic disturbances (e.g., hypoglycemia), or seizures.
  6. Motor Weakness and Paralysis
    • May be upper motor neuron (spasticity, brisk reflexes) or lower motor neuron (flaccidity, fasciculations).
    • Acute flaccid paralysis is notifiable (e.g., poliomyelitis, GBS).
  7. Sensory Disturbances
    • Less commonly reported in young children.
    • May include numbness, tingling, or loss of proprioception.
  8. Abnormal Movements
    • Includes tremors, chorea, dystonia, or tics.
    • Seen in conditions like Sydenham chorea (post-streptococcal), dystonic CP, or genetic syndromes.

57.4 Localization Along the Neuro-axis

Understanding where a lesion is located helps narrow the differential diagnosis.

  1. Cerebral Cortex
    • Lesions cause hemiparesis, seizures, or language deficits.
    • Can result from ischemia, trauma, infection, or malformations.
  2. Basal Ganglia
    • Involved in movement control.
    • Disorders cause involuntary movements (e.g., chorea, dystonia).
  3. Brainstem
    • Cranial nerve deficits (e.g., facial palsy), eye movement abnormalities, and vital sign instability.
    • Lesions are often life-threatening.
  4. Cerebellum
    • Ataxia, dysmetria, and intention tremor.
    • Tumours or infections like cerebellitis are common culprits.
  5. Spinal Cord
    • Motor and sensory level deficits, reflex changes, and incontinence.
    • Trauma or transverse myelitis is a common cause.
  6. Peripheral Nerves
    • Symmetrical weakness, absent reflexes, and distal sensory loss.
    • Seen in GBS or hereditary neuropathies.
  7. Neuromuscular Junction
    • Fluctuating weakness, especially ocular and bulbar muscles.
    • Example: Myasthenia Gravis.
  8. Muscle
    • Proximal weakness and hypotonia.
    • Seen in muscular dystrophies, myopathies, and metabolic muscle diseases.

57.5 Basic Neurological Investigations

Timely and appropriate investigations help confirm clinical suspicion.

  1. Neuroimaging
    • CT scan: Good for acute trauma or haemorrhages. Widely available in Ghana, but it has been linked to radiation exposure.
    • MRI: Better for soft tissue detail, congenital malformations, or tumours. Less accessible but ideal for subacute and chronic conditions.
  2. Electroencephalography (EEG)
    • Assesses the brain’s electrical activity.
    • Useful in seizure evaluation, epilepsy classification, and encephalopathy.
  3. Lumbar Puncture
    • Essential for evaluating CNS infections.
    • CSF analysis helps differentiate bacterial, viral, or tuberculous meningitis.
    • Ensure no signs of raised intracranial pressure before performing.
  4. Blood Tests
    • CBC, electrolytes, blood glucose, renal/liver function, malaria test.
    • Metabolic screening for inborn errors if available.
  5. Nerve Conduction Studies (NCS)/Electromyography (EMG)
    • Evaluate peripheral nerve and muscle function.
    • Useful in GBS, neuropathies, and myopathies.
  6. Genetic Testing
    • For suspected inherited or syndromic conditions.
    • May be limited in availability and affordability.

57.6 Basic Neurological Procedures

These are diagnostic and sometimes therapeutic.

  1. Lumbar Puncture (Spinal Tap)
    • Performed in suspected meningitis, encephalitis, or to measure intracranial pressure.
    • Atraumatic technique is important. Avoid in cases of suspected elevated ICP or spinal deformities.
  2. EEG Application
    • Involves placing electrodes on the scalp using the 10-20 system.
    • Should be interpreted by trained personnel.
  3. Neuroimaging Requests
    • Clinicians should provide clear clinical information and suspected diagnosis when requesting CT/MRI.
    • Sedation may be required in children for MRI.
  4. Muscle Biopsy
    • Used in diagnosing myopathies.
    • Requires sterile technique and histopathological expertise.
  5. Botulinum Toxin Injections
    • Used for spasticity in conditions like CP.
    • Requires experience and is often performed under sedation.
  6. CSF Shunt Insertion
    • Performed by neurosurgeons in hydrocephalus.
    • Ventriculoperitoneal (VP) shunt is common. Risks include infection and obstruction.

57.7 Final Notes for Medical Students in Ghana

  • Paediatric neurological disorders are common, and early recognition is crucial for better outcomes.
  • Focus on comprehensive history-taking and detailed neurological examination.
  • Understand the developmental context: some signs that are abnormal in adults are normal in infants (e.g., primitive reflexes).
  • Pay attention to public health issues like malaria, meningitis, malnutrition, and trauma, which are common in Ghana and major contributors to paediatric neurological morbidity.
  • Always consider preventable causes—promote antenatal care, immunizations (e.g., against polio, Hib, pneumococcus), good nutrition, and road safety.
  • Collaborate with neurology, paediatrics, radiology, and rehabilitation teams when managing neurological cases.