What could be causing this child’s tics and obsessive behaviour?

Case of the month: In the latest in our series on unusual cases, Dr Peter Bagshaw asks why this child suddenly developed tics and obsessive behaviour. Post your answers below!

Details of the case have been changed to ensure anonymity

Abbi is a shy 11-year-old who recently started secondary school. She had seemed to be settling in well apart from frequent colds and sore throats.

However, her mother brought her to see the GP, concerned that for the past two weeks she had become unusually clingy, and seemed to have developed facial tics and to have become obsessive in her behaviour, lining up her toys in a perfect line and becoming very fussy over food.

Her mother was concerned that she was being bullied at school, though Abbi denied this. There was no previous history of anxiety or behavioural problems, though Abbi’s father was prone to mild anxiety and depression

The GP found no other obvious abnormalities other than the tics, which consisted of frequent blinking of both eyes. He suggested Abbi was probably experiencing stress from the change of school. He considered referral to CAMHS but felt she would be unlikely to meet the criteria for acceptance, so simply reassured them both.

A week later, the mother returned in great distress. Abbi’s mental health had deteriorated dramatically. She was now sleeping in her parents’ bed because of horrific nightmares. Her school performance had plummeted, and her teacher reported she was ‘withdrawn and not herself’. Her obsessive behaviour and fears had escalated, and her mother was concerned there might be a physical cause for her symptoms, perhaps a brain tumour. Examination was again normal, with no neurological signs or fever; her chest and throat were clear.

In view of the dramatic deterioration, the GP phoned the local child psychiatrist who, to his surprise, recommended an urgent paediatric referral.

Why was an urgent referral required? What could be the diagnosis? Post your suggestions in the comments below. Answer to be revealed in the coming weeks!