Neuronal intranuclear hyaline inclusion disease (NIID) is a slowly progressive neurodegenerative disease characterized by eosinophilic hyaline intranuclear inclusions in the central and peripheral nervous system, and also in the visceral organs.
On this page:
Epidemiology
Originally considered as primarily a pediatric disease, neuronal intranuclear hyaline inclusion disease has been increasingly recognized to be a heterogeneous disease with highly variable clinical manifestations, and ante-mortem diagnosis has been difficult. Nevertheless, since the usefulness of skin biopsy and brain MRI for the diagnosis of NIID has been described, the number of NIID diagnoses has increased, in particular adult-onset NIID 4.
Clinical presentation
The clinical presentation of patients with NIHID can be varied and includes 1-3:
pyramidal tract signs
extrapyramidal signs including parkinsonism
abnormal ocular movements and oculogyric crises
generalized cognitive degeneration and behavioral changes
-
peripheral neuropathy
severe muscle atrophy and weakness
sensory impairment in the distal limbs
-
autonomic neuropathy
episodic intestinal pseudo-obstruction
urinary and fecal incontinence
cardiomyopathy: reported but uncommon
epilepsy: reported but uncommon
The diagnosis can be made using peripheral nerve biopsy (e.g. sural nerve) 1 or myenteric plexus biopsy (e.g. rectal biopsy) 2,3.
Pathology
Neuronal intranuclear hyaline inclusion disease is characterized by accumulation of eosinophilic intranuclear inclusions which can be found widely within both the central and peripheral nervous system including sympathetic and myenteric ganglion neurons, dorsal root ganglion neurons, and spinal motor neurons 1-3.
It is believed to be due to abnormal proteolysis, although the exact mechanism has as yet not been established 2,3.
The intranuclear inclusions fluoresce under ultraviolet light and are composed of uniform, fine straight filaments haphazardly arranged 3.
Radiographic features
MRI
Conventional brain MRI findings of patients with neuronal intranuclear hyaline inclusion disease strongly resemble those seen in fragile X-associated tremor/ataxia syndrome (FXTAS), including symmetric white matter involvement in combination with hyperintense changes of the middle cerebellar peduncles 4. Although not invariably present, only NIID typically presents on DWI with highly characteristic band-like and symmetric hyperintense changes of the corticomedullary junctions 4-6. This imaging feature is considered a strong indicator of NIID, while symmetric high signal changes on T2/FLAIR in the cerebellar hemispheres and along the cerebellar vermis are occasional ancillary findings 7.
Cortical contrast enhancement with corresponding edema and high signal on DWI has been found in a subset of patients with a younger age of onset, shorter duration of disease, and a higher incidence of a headache than those without enhancement. The enhanced lesions were selectively spread along the surface of posterior cortex and were clinically associated with encephalopathy-like episodes 6,8.
Treatment and prognosis
NIID is slowly progressive and has no proven therapy.
Differential diagnosis
Clinically the differential diagnosis includes 3: