|Year : 2020 | Volume
| Issue : 2 | Page : 99-105
Clinical spectrum of focal dystonias: Experience from a tertiary care center
Rupesh Prasad, Deepika Joshi, Vijay N Mishra, Rameshwar N Chaurasia, Abhishek Pathak
Department of Neurology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
|Date of Submission||26-Mar-2020|
|Date of Decision||31-May-2020|
|Date of Acceptance||22-Jun-2020|
|Date of Web Publication||28-Jul-2020|
Prof. Deepika Joshi
Department of Neurology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh.
Source of Support: None, Conflict of Interest: None
BACKGROUND: There is a paucity of literature in patients with focal dystonia from our country with certain differences in the clinical characteristics as compared to the Western population. OBJECTIVES: The aim of this study was to evaluate the clinical spectrum of patients with focal dystonia attending the neurology outpatient department and of admitted patients in neurology ward of a tertiary care hospital. MATERIALS AND METHODS: All consecutive patients of focal dystonia from October 2017 to September 2019, fulfilling the inclusion criteria were enrolled. Patients were subjected to a detailed history and thorough examination as per a predesigned pro forma. RESULTS: Of a total of 88 patients with focal dystonia, 62.5% were male. Majority of the focal dystonia (51.1%) had late adulthood onset (>40 years). Writer’s cramp was the most common type of focal dystonia (n = 38; 43.2%), but in patients older than 40 years, focal cranial dystonias (n = 28 of 43, 65.1%) were the most common. Oromandibular dystonia and blepharospasm had significantly older mean age of onset compared to focal upper limb (57.0 ± 14.05, 44.9 ± 13.83 vs. 31.5 ± 17.67; P < 0.001, P = 0.032, respectively). Most of the focal dystonias were isolated (87.5%, n = 77) and idiopathic (66%). Among the acquired causes, drugs were the most common (n = 9; 10.1%), followed by perinatal birth insult (n = 4; 4.5%). All of the drug-induced focal dystonias were oromandibular. CONCLUSION: Focal dystonia was more prevalent in males, and it had an earlier age of onset by a decade as compared to the Western population. Writer’s cramp was the most common type of focal dystonia, but in patients older than 40 years, cranial dystonias were the most common. In patients presenting with oromandibular dystonia, a drug history should be carefully sought.
Keywords: Cranial dystonia, drug-induced dystonia, focal dystonia, oromandibular dystonia, writer’s cramp
|How to cite this article:|
Prasad R, Joshi D, Mishra VN, Chaurasia RN, Pathak A. Clinical spectrum of focal dystonias: Experience from a tertiary care center. Ann Mov Disord 2020;3:99-105
|How to cite this URL:|
Prasad R, Joshi D, Mishra VN, Chaurasia RN, Pathak A. Clinical spectrum of focal dystonias: Experience from a tertiary care center. Ann Mov Disord [serial online] 2020 [cited 2022 Dec 7];3:99-105. Available from: https://www.aomd.in/text.asp?2020/3/2/99/291077
| Introduction|| |
Dystonia is a hyperkinetic movement disorder in which there is an abnormal posture of twisting nature or repetitive patterned movement or tremulous movement, which is often initiated or worsened by voluntary action. These may be associated with an overflow of muscle contraction. If only one body region is affected then it is called as focal dystonia. Previous epidemiological studies have shown the prevalence of primary focal dystonia (PFD) in the range 30 to 732 of 100,000 in the general population. Scanty literature,, is available regarding the clinical profile of focal dystonia in the Indian population, which has revealed certain differences from the Western literature. This study aimed to evaluate the clinical profile of focal dystonia at a tertiary care referral center.
| Materials and Methods|| |
This prospective observational study was conducted in the department of neurology at a tertiary care university hospital in the Eastern region of India. All the consecutive patients with dystonia were recruited from the period of October 2017 to September 2019.
During the study period, a total of 88 patients with focal dystonia were included irrespective of the cause. A detailed history and examination followed by relevant investigations were carried out in all the patients. We classified dystonia according to the consensus update on phenomenology and classification of dystonia. Both Axis 1 and Axis 2 classification schemes were applied. Dystonia was considered familial if at least one other family member in a three-generation pedigree had symptoms, suggestive of dystonia, tremor, or Parkinsonism More Details.
We analyzed the clinical characteristics of idiopathic focal dystonia separately to compare with previous studies, as previous studies were done on PFD. Investigations were performed as per patient requirement. We could not perform a genetic analysis because of financial constraints.
Data were statistically analyzed using the Statistical Package for the Social Sciences (SPSS) IBM SPSS Statistics for Windows, Version 23.0 (Armonk , New York, USA), and Microsoft Office Excel statistical software programs. Comparative analysis was performed using the chi-square test or Fisher’s exact tests for categorical variables and unpaired Student’s t test for continuous variables.
| Results|| |
A total of 88 patients of focal dystonia were included, among them 62.5% (n = 55) were males and 37.5% (n = 33) were females. The mean age of onset was 39.86 ± 18.6 years; in males, it was 40.5 ± 18.9 years, and in females, it was 38.8 ± 18.3 years without significant difference between them (P = 0.69). The mean duration of illness was 3.65 ± 5.70 years, and it was comparable between both males and females (4.2 ± 6.2 years vs. 2.8 ± 4.7 years, respectively; P = 0.28). Upper limb dystonia was the most common (n = 42, 47.7%), followed by blepharospasm (n = 23, 26.1%), oromandibular (n = 16, 18.2%), lower limb dystonia (n = 3, 3.4%), and 2 (2.3%) patients each of cervical and laryngeal dystonia.
Types of focal dystonia
Characteristics of different types of focal dystonia are shown in [Table 1]. It was found that there were no significant differences in the distribution of different types of focal dystonia between male and female patients (P = 0.085). Patients with oromandibular dystonia were older at the time of onset as compared to focal upper limb (P < 0.001) and lower limb dystonia (P = 0.032). Patients with blepharospasm were also significantly older than patients with focal upper limb dystonia at the time of onset (P = 0.026). The mean duration of illness was significantly different between different types of focal dystonia (P = 0.046).
Different age-group distributions of focal dystonia are shown in [Figure 1]. We can see that most of the patients with focal dystonia had late adulthood onset (51%).
The prevalence of different types of focal dystonia in the different age-groups is shown in [Figure 2]. We observed that with increasing age-group, the prevalence of focal upper limb dystonia decreases and that of blepharospasm and oromandibular dystonia increases.
|Figure 2: Distribution of different types of focal dystonia in different age groups|
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Focal dystonia was persistent in 48.9% (n = 43), action specific in 47.7% (n = 42), and paroxysmal in 3.4% (n = 3). Types of action-specific dystonia were writer’s cramp (90.5%, n = 38), lingual, and laryngeal dystonia (4.75%, n = 2) each. The majority of upper limb focal dystonias were the writer’s cramp (90.5%). We also found that writer’s cramp was overall the most common type of focal dystonia, which constituted 43.2% of all focal dystonias.
Clinical characteristics of writer’s cramp: Approximately 76.3% (n = 29) of patients with writer’s cramp were male, and 23.7% (n = 9) were females. Regarding the occupational history of patients with writer’s cramp, three female patients were housewives and six were students. Among male patients of writer’s cramp, eight were university students, six were in clerical jobs, five were shopkeepers and farmers each, four were teachers, and one was a policeman. Therefore, 6.6% of females and 62.1% of male patients with writer’s cramp were associated with some profession, which required more writing work. Mean age at onset was 31.5 ± 17.2 years, but in males, the onset occurred at 36.1 ± 16.6 years and in females, at 16.7 ± 8.5 years with significant difference (P = 0.002). The mean duration of illness was 5.7 ± 7.6 years, whereas in males, the duration of illness was 5.7 ± 7.6 years, which was comparable with females (5.5 ± 7.9 years; P = 0.94).
Focal dystonias were isolated in 87.5% (n = 77), that is, there were no other movement disorders or other neurological and systemic features other than tremors. Focal dystonias were combined with other movement disorders in 3.4% (n = 3) of cases. Another associated movement disorder was tic in one case and parkinsonism in two cases.
Focal dystonia was associated with other neurological (besides movement disorder) or systemic features in 9.1% (n = 8) of cases. Among other systemic or neurological features, four had hemiplegia, one had seizure, one had psychiatric feature, one had mental retardation, and one had Kayser-Fleischer ring More Details (K-F ring) hepatomegaly, and portal hypertension.
Tremor was present in 41% (n = 36) of cases. Among different types of focal dystonia, 73.1% (n = 31) of upper limb dystonia had tremor, whereas 13% (n = 3) of blepharospasm and 12.5% (n = 2) of oromandibular dystonia had tremor but none of the cervical dystonia patients had tremor, and this difference was significant (P < 0.001).
Distribution of tremor (ipsilateral vs. bilateral postural) in focal upper limb dystonia (writer’s cramp vs. nonwriter’s cramp) is shown in [Table 2]. The tremor was present in 73.7% of the writer’s cramp and in 75% of nonwriter’s cramp upper limb dystonia.
In both blepharospasm and oromandibular dystonia, patients had bilateral upper limb postural tremor.
When patients were classified according to associated dystonia then we found that 17 patients (19.3%) had dystonic tremors, 5 patients (5.7%) had tremors with dystonia, and 14 patients (15.9%) had combined dystonic tremors + tremors with dystonia.
The etiology of focal dystonia is shown in [Figure 3]. Most of the focal dystonias were idiopathic (69.3%). Of 61 idiopathic cases, three had clinical features suggestive of Paroxysmal kinesigenic Dystonia (PKD).
Etiological classification of focal upper limb dystonia
Among 42 patients of focal upper limb dystonia, 78.6% (n = 33) were idiopathic, and among them, 96.9% had writer’s cramp [Table 3]. Approximately 75% of nonwriter’s cramp focal upper limb dystonia were secondary, and among them, Tuberculous meningitis (TMB), birth insult, and Young onset Parkinson’s disease (YOPD) were the cause in one patient each. Magnetic resonance imaging (MRI) of brain of the patient of TBM showed chronic infarct in the right caudate and putamen. Among patients of writer’s cramp, 84.2% (n = 32) were idiopathic, whereas vascular insult, post-encephalitic, and Wilson’s disease were the causes in one patient each, and birth insult was the cause in three cases. In the patient with vascular insult, the non-contrast computed tomography (NCCT) of brain showed bilateral lentiform nucleus bleed with right thalamus lacunar infarct. Patient of post-encephalitis sequelae was not investigated with an MRI at the onset of disease; however, their current MRI study was normal.
Etiological classification of blepharospasm
Among patients with blepharospasm, 78.3% (n = 18 of 23) patients were idiopathic, three patients had a history of eye surgery, and one patient had a history of head trauma and conjunctivitis each. The causal association of eye surgery, conjunctivitis, and head trauma in these cases is uncertain because in them, symptoms were persistent even after the improvement of events.
Etiological classification of oromandibular dystonia
Approximately 56.3% (n = 9) of 16 patients with oromandibular dystonia had a history of drug intake, 37.5% (n = 6) patients were idiopathic, whereas one patient had a history of post-Herpes Zoster Virus (HZV) infection, in whom the symptom was persistent even after the cure of infection.
Etiological classification of cervical, laryngeal, and lower limb dystonia
Only two patients had focal cervical dystonia, and among them, one had a history of vascular insult with right thalamic bleed and one had a history of head trauma but a causal relationship cannot be established for head trauma as their imaging reports were not available. Of two patients with focal laryngeal dystonia, one was idiopathic and one had a history of vascular insult with multiple area infarcts. All three patients of lower limb dystonia were of paroxysmal dyskinesia. Family history was positive in only 9.1% (n = 8) of cases.
Comparison of idiopathic and secondary focal dystonia
There was no significant difference with respect to the age of onset and mean duration of illness between males and females in both idiopathic and secondary focal dystonia (in idiopathic, P = 0.96 and 0.46, respectively, and in secondary, P = 0.49 and 0.44, respectively) [Table 4] and [Table 5].
|Table 5: Characteristics of different focal dystonias of idiopathic and secondary etiology|
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The prevalence of different types of focal dystonias in idiopathic and secondary cases is shown in [Figure 4]. The most common idiopathic focal dystonia was focal upper limb dystonia (54.1%, n = 33), but oromandibular dystonia was the most common secondary focal dystonia (37%, n = 10).
|Figure 4: Distribution of different types of focal dystonias among idiopathic and secondary case|
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In idiopathic cases, focal upper limb dystonia started at a significantly early age than focal oromandibular dystonia (P = 0.007).
The mean age of onset was not significantly different between idiopathic and secondary cases of different types of focal dystonias (P = 0.43, 0.90, and 0.08 for upper limb dystonia, oromandibular dystonia, and blepharospasm, respectively).
The duration of illness was also not significantly different between idiopathic and secondary cases of different types of focal dystonias (P = 0.15, 0.26, and 0.50 for upper limb dystonia, oromandibular dystonia, and blepharospasm, respectively).
| Discussion|| |
In this study, we found that focal dystonia was more prevalent in males; they constituted 62.5% of total cases. Even in idiopathic cases, 62.1% were males. This finding was similar to the previous Indian studies, where the male population constituted the majority of PFD, ranging from 76.8% to 79.1%. But in the Western literature,, females comprised the majority (59.2%–69.2%) of the focal dystonia cases. The reason for the low prevalence of dystonia in females in our cohort as compared to the Western studies could be due to less healthcare-seeking behavior of women in the rural area, low literacy rate, and ignorance about the condition.
Previous institution-based study from India had found that the mean age of onset of focal dystonia was the fourth decade, similar to our study. But in the Western studies,, dystonia started one decade later, that is, in the fifth decade. The reason for early onset in the Indian population than the Western population could be a difference in their genetic makeup.
In our study, upper limb dystonia was the most common type of focal dystonia both in total dystonia cases and in idiopathic cases (47.7% and 54.1%, respectively). Literature search carried out revealed that the previous studies from India,,, also found upper limb dystonia as being the most common type of focal dystonia with frequency ranging from 32% to 65.8% of total focal dystonia cases. This finding was different from the findings in the Western studies,, where cervical dystonia was the most common type of PFD with frequency ranging from 50% to 74% of total focal dystonia. The difference may be due to a difference in the genetic makeup of our patients, or possibly an ignorance by the patients, as cervical dystonia interferes less with the occupation than upper limb dystonia.
In our study, there was a significant difference [Figure 2] in the types of focal dystonia between patients older and younger than 40 years at onset (P = 0.01). In patients younger than 40 years, the upper limb dystonia was the most common type (n = 28 of 43, 65.1%), which is similar to the finding in the previous study. But we found that patients, who were aged more than 40 years at the onset, had focal cranial dystonia (oromandibular + blepharospasm) as the most common type of focal dystonia (n = 28 of 45, 62.22%).
Types of focal dystonia
Similar to previous studies,,, the writer’s cramp was more frequent in males and the mean age of onset was in the fourth decade. We also found that in females, the writer’s cramp had early onset than males (P = 0.002). This result was also consistent with the findings in the previous study.
Western literature had reported that blepharospasm was more prevalent in females, and they constituted 68.7%–80% of total cases., But the previous Indian studies, had reported male predominance in blepharospasm with frequency ranging from 56.25% to 70% of males in blepharospasm cases. Our findings are also different than Western studies as we found that focal blepharospasm was almost equally prevalent between males and females both in total and idiopathic focal blepharospasm. This difference between Indian and Western studies may be due to less outdoor activity in females as unemployment is more prevalent among females than males or maybe less healthcare-seeking behavior in females due to more illiteracy than males. The mean age of onset of focal blepharospasm was in the fifth decade for both total and idiopathic cases, which were similar to previous studies.,,,
We found that focal oromandibular dystonia was equally prevalent in males and females if we consider total cases irrespective of etiology, but in idiopathic focal oromandibular dystonia, females outnumbered the males with male:female ratio of 2:4. But Western literature had reported oromandibular dystonia to be more prevalent in females as they constituted 68.5%–68.8% of total cases., This difference may be due to less proportion of idiopathic cases in our study. The idiopathic cases were only 37.5% of the total oromandibular dystonia in our study, whereas in their studies, it was 63%–71%. In our study, the mean age of onset of oromandibular dystonia was in the sixth decade for both total and idiopathic focal oromandibular dystonia, which is consistent with previous studies.,
Tremor was present in 41% (n = 36) of cases, which was not different than previous studies from India where it was reported in 35.6%–42.1% of patients with focal dystonia.,
Most of the focal dystonias were idiopathic (69.3%), which is consistent with the previous study. Among acquired causes, drugs were the most common cause (n = 9, 10.1%) followed by perinatal birth insult (n = 4, 4.5%). All of the drug-induced focal dystonias were oromandibular.
Among focal cranial dystonia, etiology was different for upper cranial and lower cranial dystonia as we found that blepharospasm was most commonly idiopathic (78.3%), whereas focal oromandibular dystonia was most commonly acquired (62.5%). In oromandibular dystonia, the most common acquired cause were drugs (90%).
| Conclusion|| |
In this hospital-based tertiary care center study, focal dystonia was the most prevalent in males, and the age of onset was much early compared to the Western population. Writer’s cramp was the most common type of focal dystonia. Drug-induced dystonia was the most common acquired cause of dystonia in our patients, and all drug-induced cases were oromandibular dystonia.
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Conflicts of interest
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]