Unusual sites of primary dystonia in adults: A series of three patients
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.226456
Source of Support: None, Conflict of Interest: None
Dystonia is a hyperkinetic movement disorder characterized by involuntary sustained or intermittent contractions leading to twisting or abnormal postures. Adult onset focal dystonia usually begins in the craniocervical or brachial region with the most common one being spasmodic torticollis, blepharospasm and spasmodic dysphonia. The spread of dystonia to other parts of the body is dependent upon the age of onset and the site of involvement. Action dystonia with onset in the legs or arms manifesting before the age of 26 years has a strong propensity to become generalized. On the other hand, dystonia starting in the cranial and cervical regions in an adult tends to remain focal. The lower extremity is rarely involved in adult onset primary dystonia whereas it is commonly affected in childhood onset cases. When dystonia affects the lower limb at onset in adults, it usually has a secondary cause inclusive of Parkinson's disease, stroke, trauma, paroxysmal dystonia, etc. The other unusual and rare dystonia in adults is idiopathic axial dystonia which presents with truncal stiffness and lumbar hyperlordosis. With this background, we report two patients of adult onset primary foot dystonia and one patient of axial dystonia who presented to our institute. We also exhibit the videos of their dytonia.
A 57-year old male patient presented with curling of his right foot for the last 5-6 years. This would occur on walking and standing. There was no history of intake of dopamine antagonists and his family history was negative. Examination showed inversion and plantar flexion of the right foot and toes. The foot dystonia disappeared on backward walking [Video 1]. Rest of the neurological examination was normal with no evidence of Parkinson's disease. Dystonia did not affect any other parts of the body. Extensive testing to rule out secondary causes of dystonia including ceruloplasmin, parathyroid hormone (PTH) levels and magnetic resonance imaging (MRI) of the brain was normal. Genetic testing for DYT 1 (dystonia 1 gene) was negative. He showed only marginal effect with drugs (levodopa and trihexiphenidyl) with no relief with botulinum toxin injection that was tried once. Carbamazepine was also tried thinking of paroxysmal kinesigenic dystonia but showed no effect.
A 65-year old female patient presented with difficulty in walking of a 3-year duration. She described it as an involuntary movement of her right leg on walking. Examination revealed both proximal and distal involvement in the form of right hip flexion, hip abduction, foot plantar flexion and flexion of the toes on walking [Video 2]. She was under follow up of an orthopaedician. MRI lumbosacral spine showed mild disc bulge at L4-L5. She was initially diagnosed as having stress fracture of a metatarsal bone of the right foot and was treated with a plaster but had no relief in her pain. Later, she even underwent total knee replacement at some other hospital with no improvement being evident postoperatively. Again, the family history was negative. All the pertinent investigations to rule out secondary causes of dystonia came out to be normal. Genetic testing was not carried out because of financial constraints. She showed a mild relief with baclofen.
A 55-year old male patient presented with stiffness of muscles of the lower back after walking for a few steps for the last 1.5 years. Examination revealed spasm of the paraspinal muscles with exaggerated lumbar lordosis which improved on backward walking ([Video 3]: Pre-treatment). Possibility of stiff person syndrome versus axial dystonia was considered. He was initially tried on levodopa 125 mg thrice daily for one month with no relief. His contrast enhanced computed tomography (CECT) of the chest and abdomen, and whole body fludeoxyglucose positron emission tomography (FDG PET) was normal. Serum anti-glutamic acid decarboxylase (GAD) antibody, anti-transglutaminase (TTG) and human leucocyte antigen (HLA) B27 came out to be negative. Paraneoplastic antibody panel was sent to rule out localized stiff person syndrome but it was negative. He showed significant response with anticholinergics (trihexiphenidyl) [[Video 4]: Post-treatment].
We report two patients of adult onset primary lower limb dystonia without any evidence of a secondary etiology. Various secondary causes of dystonia include structural lesions, Wilson disease, dopa responsive dystonia, tardive dystonia, hypoparathyroidism, etc. There are a few reports or case series of primary adult onset foot dystonia in the literature.,, In both our patients, there was action dystonia which differentiates it from psychogenic dystonia in which dystonia is usually fixed. There was not even spread of dystonia to other parts of the body. This contrasts with childhood onset foot dystonia which is almost always generalized.
Adult onset foot dystonia is commonly seen in the setting of parkinsonism and may even herald its onset. However, the long duration of the illness with no signs of parkinsonism in both our patients on examination, argues against it. One caveat is that we have not done dopaminergic imaging in our patients. Lastly, it is important to create awareness about this rare entity as it may prevent unnecessary surgeries, as was seen in our second patient.
Dystonia involving the truncal musculature is usually secondary to a neurodegenerative etiology or is a manifestation of the tardive syndrome. Idiopathic truncal dystonia involves involuntary contractions and postures of the paraspinal, abdominal or chest muscles. It is an uncommon condition which affects men in their fifth decade of life. The largest series has been reported by Bhatia et al., that described the features of axial dystonia in 18 patients. Ehrlich and Frucht described seven cases of idiopathic truncal dystonia in their retrospective case series. Idiopathic truncal dystonia is usually considered refractory to oral medications and may require botulinum toxin or even deep brain stimulation., However, our patient showed a dramatic response to oral anticholinergic drugs. This may be due to the presence of a milder severity of dystonia in our patient.
Stiff person syndrome can mimic axial dystonia, which we ruled out in our patient. Balint et al., have succinctly reported the differentiating features between these two similar conditions. The major difference is that stiffness is more constant in stiff person syndrome when compared to axial dystonia in which there is clearly a mobile element to the trunk stiffness.
To conclude, adult onset focal dystonia usually begins in the craniocervical or the brachial regions. Foot and truncal muscles are uncommonly involved in the manifestations of adult onset focal dystonia.
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