AN UNSTEADY CHILD
History
Toby is a 4.5-year-old boy referred to children’s outpatients by his GP with a history of apparent stiffness in his neck. About 6 weeks previously he complained of a ‘dizzy head’ and became reluctant to walk home after school. Subsequently he seemed to find it difficult to look upwards but seemed fine when looking from side to side. He has also been rubbing his head and crying. In the past 3 weeks Toby has had several episodes of vomiting and at the time holds his neck in pain. There have been no other gastrointestinal symptoms nor any fevers and there has been some improvement with paracetamol. Toby has become increasingly clumsy and has had several unexpected falls even when sitting. Having walked up stairs independently, he now wants to hold the rail or someone’s hand and no longer runs with confidence. He has fallen off his tricycle twice and no longer wants to ride it. Toby is the youngest of three children and has no significant past medical or family history. He had chickenpox 3 years ago. Up to now his development has been normal and he is fully immunized.
Examination
Toby appears a generally healthy boy with his height and weight on the 25th centiles and his head circumference on the 50th centile. There is no cervical lymphadenopathy and passive movements of his neck are normal, although he is reluctant to look up to the ceiling. His pulse is 88 beats/min and his blood pressure is 85/60 mmHg. There are no murmurs, and examination of the respiratory and abdominal systems is unremarkable. There are no neurocutaneous markers. There is no nystagmus and external ocular movements are normal. Fundoscopy is very difficult because he screws up his eyes, but a brief glimpse of the right fundus suggests blurred disc margins. The remainder of the cranial nerves appear normal. He has a broad-based, unsteady gait and cannot walk heel to toe. However, muscle bulk, tone, power and reflexes are normal in both arms and legs. He is very unsteady when standing with his eyes shut. He tries very hard with the finger–nose test but misses both every time, nor can he touch his nose accurately with his eyes shut. He can pick up small objects without a problem.
Questions
• What movement disorder do these symptoms and signs describe?
• Where is the pathology likely to be located and what complication has arisen?
• What investigation does he need?
Medicine
Toby has symptoms and signs of ataxia – the inability to make smooth, accurate and coordinated movements. Observation during play is the key to much of the neurological examination in a child. It is crucial to take account of the developmental stage of the child – a broad-based, unsteady gait is normal for a child who is just starting to walk but not in a previously confident 4-year-old. Other tests of ataxia include the heel–shin test and dysdiadochokinesia, but he is probably too young for these to be interpretable. Make these formal parts fun and most children will very happily do their best. Remember that, by definition, all tests for movement disorders require the ability to move; hence tone and power must be assessed. Similarly he must be able to see to do the coordination tests. Ataxia is usually due to disorders of the cerebellum and/or the sensory pathways in the posterior columns of the spinal cord. The neck pain, rubbing of his head in distress and vomiting are highly suggestive of raised intracranial pressure (ICP). Unfortunately, this is frequently missed in children because they are poor at localizing pain and the symptoms are relatively non-specific and common. Fundoscopy is notoriously difficult in children because they don’t cooperate and you may only get the briefest glimpse. Hypertension and bradycardia are usually late signs when the child is obtunded. The classic early morning headache and effortless vomiting of adults with raised ICP is less common in children. The cerebellum is therefore the most likely location for the pathology, with the raised ICP being due to hydrocephalus secondary to obstruction of the fourth ventricle. It could be due to a congenital anomaly of the cerebellum, such as the Dandy–Walker syndrome or a Chiari malformation, but his symptoms are relatively recent. Vomiting is a major feature of acute cerebellar ataxia following a viral illness such as chickenpox, but the onset is sudden and often severe with nystagmus and dysarthria and the other symptoms and signs of raised ICP are often absent. A space-occupying lesion is most likely in our case. In children, two-thirds of brain tumours are located in the posterior fossa compared with one-third in adults. Toby needs an urgent MRI (or CT) scan.
The MRI scan (Fig. 52.1) shows a vermian midline posterior fossa tumour with hydrocephalus. At posterior craniotomy, as much tumour as possible was resected and the hydrocephalus resolved without him needing a ventriculoperitoneal shunt. Histology confirmed a medulloblastoma, a primitive neuroectodermal tumour (PNET), which is the most common malignant brain tumour of childhood. Medulloblastomas frequently spread through the leptomeninges and patients require cerebrospinal fluid analysis. Treatment recognizes this risk and usually includes craniospinal irradiation. In recent years prognosis has improved to 70–80 per cent with the introduction of additional intensive systemic chemotherapy.
KEY POINTS
• Raised intracranial pressure in children frequently presents with non-specific symptoms.
• Two-thirds of childhood brain tumours are located in the posterior fossa.
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