Bobble-head doll syndrome (BHDS) is a rare neurological condition which causes involuntary ‘bobbing’ or repetitive anterior-posterior movement of the head, resembling that of a bobble-head doll. This rare condition affects young children, around 3 years of age and thus far, fewer than 60 cases have been reported in the literature.
What are the Clinical Characteristics/Symptoms of BHDS?
The primary symptom of BHDS is the bobbing of the head and sometimes shoulders at a frequency of 2-3 times per second. These are involuntary and the affected individual is often unaware that these movements are occurring.
Although the bobbing movement is involuntary, performing simple mental tasks such as arithmetic or spelling can temporarily halt the movement. However, once the mental task is complete, bobbing resumes almost immediately. Furthermore, bobbing of the head also stops during sleep.
What Causes BHDS?
The exact cause of BHDS is still unknown, however, one classical pathological hallmark of BHDS is that of the presence of large cystic lesions within the third ventricle. Cerebrospinal fluid (CSF) accumulates in the third ventricle (hydrocephalus).
The cystic lesions can directly impede access to various periventricular structures causing a build-up of CSF in the third ventricle. The cysts themselves may press against key motor nuclei within the brainstem and the thalamus, which may cause of the symptoms of BHDS.
Diagnosis is definitively made with neurological examination and neuroimaging (e.g. MRI) to reveal cystic lesions compressing the third ventricle, causing hydrocephalus. If the remainder of the nervous system remains normal, in structure, then a diagnosis can be made.
How is BHDS Treated?
There are several treatment strategies that target cystic lesions and the build-up of CSF within the third ventricle.
Surgical removal of a cyst from the third ventricle can cause full recovery of BHDS symptoms in as many as half of all patients. Cysts within the third ventricle obstruct clearance pathways for CSF (such as the foramen of Monro), and consequently lead of BHDS.
Another successful strategy is the implantation of a ventriculo-peritoneal shunt to reduce intracranial pressure (caused by CSF build-up). The reduction of pressure within the enlarged third ventricle will stop thalamic and brainstem nuclei being compressed therefore completely halting all symptoms of BHDS.
Treatment strategy will depend on the size and location of the cyst, or the amount of intracranial pressure due to CSF accumulation. The prognosis depends on how early a diagnosis is made, and late interventions may not completely cure the symptoms of BHDS. Therefore, early diagnosis is critical in the hope of complete recovery of all symptoms.
Sources
- Reddy et al, 2014. J Pediatr Neurosci. 9(2):175-77 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4166848/
- rarediseases.info.nih.gov/diseases/9731/bobble-head-doll-syndrome
