Spasmus nutans is an acquired form of nystagmus that occurs in children typically within the first 2 years of life. It presents as a clinical triad of 1) nystagmus 2) head bobbing 3) torticollis. The current theory holds among researchers that head bobbing and torticollis are compensatory mechanisms that improve vision by reducing the frequency and asymmetry of the nystagmus.
In most cases, spasmus nutans is a benign idiopathic disorder, however studies with monozygotic twins have also revealed a possible familial component. Usually the disorder disappears by age 3 or 4. There are rare cases that spasmus nutans is associated with chiasmal or suprachiasmal lesions in the brain thus warranting neuroimaging on babies diagnosed with this disorder. Furthermore, this condition has also been associated with retinal dystrophies such as congenital stationary night blindness which can be confirmed by Electroretinography.
The diagnosis can be made if all 3 components of the triad are present. If associated with a intracranial tumor or retinal dystrophy, neuroimaging and ERG can help confirm these findings.
Nystagmus is usually bilateral and characterized by high frequency, small amplitude (shimmering) nystagmus. It has also been described as monocular, asymmetric, and occasionally intermittent. Furthermore, it can be horizontal, vertical, rotatory and variable in different gaze positions. Some form of head bobbing and neck posturing is also present. Warning signs to look for that might warrant a more hasty referral for brain MRI would be any evidence of optic nerve dysfunction such as optic disc pallor or relative afferent pupillary defect. While it would be ideal to be able to determine whether a patient with spasmus nutans has associated CNS disease based on the eye and head movements alone, studies have indicated that there is no difference between the patients with spasmus nutans with and without CNS lesions. This once again confirms that the differentiation must be made on the basis of neuroimaging.
As previously discussed, the diagnosis of spasmus nutans warrants neuroimaging, usually MRI, as this is generally more sensitive in revealing pathology in anterior visual pathway i.e. optic nerve glioma than CT scan. Also, electroretinography (ERG) should be considered in children with spasmus nutans and clinical signs of a retinal dystrohy such as myopia or paradoxical pupils.
- SN-like nystagmus (condition where children have nystagmus, head nodding and abnormal head position similar to SN but symptoms are associated with low vision)
- Optic nerve hypoplasia
- Congenital stationary night blindness
- Bardet-Biedl syndrome
- Neurologic diseases
- Optic pathway glioma (chiasmal)
- Arachnoid cyst
- Opsoclonus-myoclonus syndrome
- Diencephalic syndrome
- Idiopathic infantile nystagmus
- Empty sella
Besides the aforementioned neuroimaging and ERG (as clinician deems fit), there are no other management strategies as this is a self-limited condition. Obviously, it is important to treat the underlying CNS lesion.
Very good. Long term follow up studies have shown that good visual acuity can be expected in patients with spasmus nutans. However, often subclinical nystagmus persists until at least ages 5 to 12.
- Basic and Clinical Sciences Course (BCSC): Pediatric Ophthalmology and Strabismus. Spasmus Nutans, 2013-2104: 324.
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- Gottlob I, Zubcov AA, Wizov SS, Reinecke RD. Head nodding is compensatory in spasmus nutans. Ophthalmology. 1992 Jul;99(7):1024-31.
- Gottlob I, Zubcov A, Catalano RA, Reinecke RD. Koller HP, Calhoun JH, Manley DR. Signs distinguishing spasmus nutans (with and without central nervous system lesions) from infantile nystagmus. Ophthalmology. 1990 Sep;97(9):1166-75.