Femur Fractures in 5 Individuals With Pantothenate Kinase-associated Neurodegeneration: The Role of Dystonia and Suggested Management.

BACKGROUND: Pantothenate kinase-associated neurodegeneration (PKAN) is a rare, neurodegenerative disorder that manifests with progressive loss of ambulation and refractory dystonia, especially in the early-onset classic form. This leads to osteopenia and stress on long bones, which pose an increased risk of atraumatic femur fractures. The purpose of this study is to describe the unique challenges in managing femur fractures in PKAN and the effect of disease manifestations on surgical outcomes. METHODS: A retrospective case review was conducted on 5 patients (ages 10 to 20 y) with PKAN with a femur fracture requiring surgical intervention. Data regarding initial presentation, surgical treatment, complications, and outcomes were obtained. RESULTS: All patients were non-ambulatory, with 4 of 5 patients sustaining an atraumatic femur fracture in the setting of dystonia episode. One patient had an additional contralateral acetabular fracture. Postoperatively, 4 of the 5 patients sustained orthopaedic complications requiring surgical revision, with 3 of these secondary to dystonia. Overall, 4 required prolonged hospitalization in the setting of refractory dystonia. CONCLUSION: Femur fractures in PKAN present distinct challenges for successful outcomes. A rigid intramedullary rod with proximal and distal interlocking screws is most protective against surgical complications associated with refractory dystonia occurring during the postoperative period. Multidisciplinary planning for postoperative care is essential and may include aggressive sedation and pain management to decrease the risk of subsequent injuries or complications. LEVEL OF EVIDENCE: Level IV.

Deep Brain Stimulation (DBS) with Subthalamic Nucleus (STN) as Target for Pediatric Patients with PKAN.

OBJECTIVE: Dystonia in pantothenate kinase-associated neurodegeneration (PKAN) is progressive despite medication. Deep brain stimulation (DBS) was reported to effectively provide symptom relief. No consensus exists in candidate and target selection for DBS. We aimed to demonstrate effectiveness of subthalamic DBS (STN-DBS) placement in pediatric patients with PKAN. METHODS: We reviewed consecutive series of pediatric patients diagnosed with PKAN and treated with STN-DBS from 2016 to 2019 in our institution. Each case was described in detail. Preoperative and postoperative Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) were assessed to evaluate functional improvement at follow-up. RESULTS: Seven pediatric patients were included. Mean age of initial onset was 0.6 ± 0.5 years and presentation to clinics was 6.6 ± 1.3 years. Mean preoperative BFMDRS was 73.3 ± 3.5. Following STN-DBS, for mean follow-up duration of 13.0 ± 10.7 months, mean BFMDRS was 37.3 ± 12.6, translating to score improvement of 36.0 ± 12.9 (P < 0.001), and percentage improvement of 49.0 ± 18.0%. CONCLUSIONS: This case series demonstrated that STN-DBS is an effective symptom-based treatment for pediatric patients with PKAN.

Redesigning therapies for pantothenate kinase-associated neurodegeneration.

Pantothenate kinase-associated neurodegeneration (PKAN) is an incurable rare genetic disorder of children and young adults caused by mutations in the PANK2 gene, which encodes an enzyme critical for the biosynthesis of coenzyme A. Although PKAN affects only a small number of patients, it shares several hallmarks of more common neurodegenerative diseases of older adults such as Alzheimer's disease and Parkinson's disease. Advances in etiological understanding and treatment of PKAN could therefore have implications for our understanding of more common diseases and may shed new lights on the physiological importance of coenzyme A, a cofactor critical for the operation of various cellular metabolic processes. The large body of knowledge that accumulated over the years around PKAN pathology, including but not limited to studies of various PKAN models and therapies, has contributed not only to progress in our understanding of the disease but also, importantly, to the crystallization of key questions that guide future investigations of the disease. In this review, we will summarize this knowledge and demonstrate how it forms the backdrop to new avenues of research.

Clinical course of patients with pantothenate kinase-associated neurodegeneration (PKAN) before and after DBS surgery.

INTRODUCTION: Pantothenate kinase-associated neurodegeneration (PKAN) is a rare autosomal recessive disorder with a progressive clinical course. In addition to symptomatic therapy, DBS has been increasingly recognized as a potential therapeutic strategy, especially in severe cases. Therefore, we wanted to report our experience regarding benefits of DBS in five PKAN cases in 3-year follow-up study. METHODS: Five genetically confirmed PKAN patients from Serbia underwent GPi-DBS. To assess clinical outcome, we reviewed medical charts and applied: Schwab and England Activities of Daily Living Scale (S&E), EQ-5D questionnaire for quality of life, Patient Global Impression of Improvement (GPI-I), Functional Independence Measure (FIM), Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS), Barry Albright Dystonia Scale (BAD). Patients were evaluated in five visits: at the disease onset, 5 years after the onset, before surgery, 6 months and 14-36 months after the surgery. Improvement of 20% was accepted as significant. RESULTS: Overall, dystonia significantly improved after GPi-DBS at 6 and 14-36 months postoperatively, when assessed by the BFMDRS and BAD. However, two patients failed to improve considerably. Four patients reported improvement on GPI-I, while one remained unchanged. Three patients reported significant improvement, when assessed with S&E and FIM. EQ-5D showed the most prominent improvement in the domains of mobility and pain/discomfort. CONCLUSION: Three out of our five patients experienced beneficial effects of the GPi-DBS, in up to 36 months follow-up. Two patients who had not reached significant improvement had longer disease duration; therefore, it might be reasonable to recommend GPi-DBS as soon as dystonia became disabling.

Deep brain stimulation for pantothenate kinase-associated neurodegeneration: A meta-analysis.

BACKGROUND: Pantothenate kinase-associated neurodegeneration is a rare autosomal-recessive disorder, characterized by progressive neurodegeneration associated with brain iron accumulation. DBS has been trialed to treat related movement disorders, particularly dystonia. The objective of this study was to determine the outcome and safety of DBS for pantothenate kinase-associated neurodegeneration. METHODS: We performed a meta-analysis using independent participant data (n = 99) from 38 articles. Primary outcome was change in movement and disability scores of the Burke-Fahn-Marsden Dystonia Rating Scale 1 year postoperatively. Secondary outcomes were response rate and complications. RESULTS: Patients with classic-type (n = 58) and atypical-type (n = 15) pantothenate kinase-associated neurodegeneration were operated on at a median age of 11 and 31 years, respectively (P < 0.001). GPi was primarily targeted (n = 87). Mean dystonia movement score improved 1 year following GPi-DBS (-26%; 95% confidence interval, -37% to -15%), particularly in atypical versus classic cases (-45% vs -16%; P < 0.001). At least 30% improvement was observed in 34% of classic versus 73% of atypical cases (P = 0.04). Higher preoperative score and atypical type predicted larger improvement. GPi-DBS improved dystonia disability score in atypical (-31%; 95% confidence interval, -49% to -13%) but not classic (-5%; 95% confidence interval, -17% to 8%) cases. Prevalence of surgical infections (6%) and hardware failure (7%) was similar to other dystonia etiologies. Two patients died within 3 months. There was insufficient data to describe outcome > 1 year following GPi-DBS or with other DBS targets. Overall, small sample sizes limited generalizability. CONCLUSIONS: This meta-analysis provides level 4 evidence that GPi-DBS for pantothenate kinase-associated neurodegeneration may improve dystonia movement scores in classic type and atypical type and disability scores in atypical type 1 year postoperatively. © 2019 International Parkinson and Movement Disorder Society.

A therapeutic approach to pantothenate kinase associated neurodegeneration.

Pantothenate kinase (PANK) is a metabolic enzyme that regulates cellular coenzyme A (CoA) levels. There are three human PANK genes, and inactivating mutations in PANK2 lead to pantothenate kinase associated neurodegeneration (PKAN). Here we performed a library screen followed by chemical optimization to produce PZ-2891, an allosteric PANK activator that crosses the blood brain barrier. PZ-2891 occupies the pantothenate pocket and engages the dimer interface to form a PANK•ATP•Mg2+•PZ-2891 complex. The binding of PZ-2891 to one protomer locks the opposite protomer in a catalytically active conformation that is refractory to acetyl-CoA inhibition. Oral administration of PZ-2891 increases CoA levels in mouse liver and brain. A knockout mouse model of brain CoA deficiency exhibited weight loss, severe locomotor impairment and early death. Knockout mice on PZ-2891 therapy gain weight, and have improved locomotor activity and life span establishing pantazines as novel therapeutics for the treatment of PKAN.

Deep brain stimulation in the globus pallidus compensates response inhibition deficits: evidence from pantothenate kinase-associated neurodegeneration.

Fronto-striatal loops are important for many cognitive control processes, like response inhibition, and it has been suggested that the globus pallidus is of particular importance for these processes. In the current study, we investigate the effect of deep brain stimulation in the GP on response inhibition processes by means of neurophysiological (EEG) methods. We perform a case-control study in neuroaxonal dystrophy pantothenate kinase-associated neurodegeneration (PKAN) using single-case statistics. We control the signal-to-noise ratio of the EEG data. The data show that disease-related changes in the globus pallidus lead to dysfunctions in response inhibition processes. Dysfunctions in the GP seem to affect controlled, but not automatized behavior as evidenced by an increased rate of false alarms and attenuation of inhibition-related neurophysiological correlates. With respect to controlled behavior in terms of response inhibition, it seems that pre-motor subprocesses and not evaluation subprocesses are affected. Deep brain stimulation in the globus pallidus seems to be able to compensate the effects of disease-related changes in this structure and normalizes response inhibition performance and their electrophysiological correlates in PKAN.

Deep brain stimulation as treatment for dystonic storm in pantothenate kinase-associated neurodegeneration syndrome: case report of a patient with homozygous C.628 2 T > G mutation of the PANK2 gene.

Pantothenate kinase-associated neurodegeneration (PKAN) syndrome is an autosomal-recessive neurodegenerative disease that causes progressive generalized dystonia. Currently, the disorder remains pharmacologically intractable. Herein we report the first case in which deep brain stimulation helped to relieve dystonic storm in a patient with PKAN syndrome who had homozygous c.628 2 T > G mutation of the PANK2 gene. A 10-year-old boy with PKAN disease presented with dystonic storm and was admitted to the emergency department. Examination revealed generalized dystonia and impaired breathing due to involvement of the respiratory muscles. The patient underwent surgery for bilateral globus pallidus internus deep brain stimulation. The patient showed marked response to treatment.

Pantothenate kinase-associated neurodegeneration in Korea: recurrent R440P mutation in PANK2 and outcome of deep brain stimulation.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the mutation status of PANK2 among Korean patients with pantothenate kinase-associated neurodegeneration (PKAN) and to document the outcome of pallidal deep brain stimulation (DBS). METHODS: Direct sequencing and deletion/duplication analysis of PANK2 were conducted in 12 patients (11 unrelated) with PKAN, diagnosed on the basis of extrapyramidal dysfunction and the 'eye-of-the-tiger sign' on brain magnetic resonance imaging (MRI). Pallidal DBS was conducted in four patients, and the outcomes were measured using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). RESULTS: A PANK2 mutation was identified in both alleles in all patients. The most prevalent mutation was c.1319G>C (p.R440P) in 8/22 mutated alleles (36%). An intragenic deletion ranging from exons 2 to 4 was found in one allele (1/22, 4.5%) using deletion/duplication analysis. The outcome of pallidal DBS was favorable in two patients with atypical PKAN and moderate severity of dystonia. However, two patients with typical PKAN and relatively severe symptoms showed variable responses. CONCLUSIONS: The c.1319G>C (p.R440P) mutation appears to be a founder genotype among Korean patients with PKAN. Furthermore, this study provides additional data for the recent international effort to evaluate the efficacy of pallidal DBS in the treatment of patients with PKAN.

Cognitive functioning in children with pantothenate-kinase-associated neurodegeneration undergoing deep brain stimulation.

AIM: To examine the cognitive functioning of young people with pantothenate-kinase-associated neurodegeneration (PKAN) after pallidal deep brain stimulation (DBS). PKAN is characterized by progressive generalized dystonia and has historically been associated with cognitive decline. With growing evidence that DBS can improve motor function in adults and children with PKAN, there is now the opportunity to study the cognitive profiles of these patients over time. METHOD: We present a case series of seven children (mean age 11 y 7 mo, SD 3 y 2 mo) undergoing bilateral pallidal DBS for the management of severe PKAN-associated dystonia. We administered standardized measures of intellectual ability and memory where possible, before DBS and 1 to 4 years after DBS. RESULTS: No cognitive decline was observed and scores improved in all but one child (whose dystonia could not be adequately controlled owing to multiple medical problems). In line with a stabilization or reduction in their dystonia, all but one child was able to tolerate longer assessment sessions and complete either the same or a greater number of subtests. INTERPRETATION: These findings suggest that apparent cognitive impairments may reflect difficulties in accessing cognition owing to severity of dystonia. Intellectual decline previously associated with PKAN may have been overestimated.

Deep brain stimulation as a mode of treatment of early onset pantothenate kinase-associated neurodegeneration.

We report a case of a young girl with early onset pantothenate kinase-kssociated neurodegeneration (PKAN) whose initial clinical manifestation was ataxia at the age of 2.5 years. Subsequently the patient presented to us with refractory severe dystonia resulting in essentially complete loss of motor control. She had a mutation in PANK2 gene consisting of an aminoacid change of Alanine to Valine in exon 5 (A382V). After Globus Pallidus deep brain stimulation (DBS) at the age of 11 years, the patient regained useful motor function and speech with a marked decrease in the severity of the dystonia. The patient's condition gradually returned to her pre-DBS status when the device had to be removed 3 months later due to infection. Our case is the sixth case with classical PKAN that was treated by Globus Pallidus stimulation, the fifth one to have a favorable response to it and the only one in whom response was proven by the inadvertent removal of the DBS device due to infection. In addition, our case had a novel mutation and novel clinical features (onset with ataxia, occurrence of early seizure activity) on top of her other symptoms that were otherwise typical of early onset disease.

Pallidal stimulation for pantothenate kinase-associated neurodegeneration dystonia.

Pantothenate kinase-associated neurodegeneration is associated with generalised dystonia and cognitive deterioration. Limited evidence suggests that pallidal deep brain stimulation improves physical functioning. This is a report of the assessment and treatment of a severely affected patient in whom pallidal deep brain stimulation improved both physical and psychosocial functioning. Implications for treatment are briefly discussed.

Off-period dystonia in Parkinson's disease but not generalized dystonia is improved by high-frequency stimulation of the subthalamic nucleus.

STN-HFS is well known to improve patients with IPD. Because off-period dystonia mimics focal or generalized dystonia of other causes, we proposed bilateral STN-HFS to some patients with generalized dystonia. The aim of this study was to compare the efficacy of STN stimulation on off-period dystonia and generalized dystonia. From a larger series of patients with IPD, we selected 22 patients based on the presence of severe preoperative off-period dystonia rated > or = 3 in least one limb on a severity score ranging from 0 to 4. Four patients with generalized dystonia (Hallervorden-Spatz disease, n = 3; primary, n = 1) underwent bilateral STN-HFS. Dystonia of the four limbs was rated on video recordings in all patients before surgery and 3 months after surgery. In IPD, bilateral STN stimulation reduced the severity of off-period dystonia by 70% on the four limbs (preoperative mean severity score = 2.03 +/- 1.49; postoperative mean severity score = 0.60 +/- 0.78). In contrast, bilateral STN-HFS had no effect on generalized dystonia (preoperative mean severity score = 3.25 +/- 0.77; postoperative mean severity score = 3.12 +/- 0.62). Despite clinical similarities between off-period dystonia in Parkinson's disease and generalized dystonia in certain cases, the effect of chronic bilateral STN-HFS differs. STN stimulation is highly effective in off-period dystonia of IPD, whereas it does not improve generalized dystonia. The pathophysiologic mechanisms underlying dystonia in these two disorders are still unknown. Assuming that the mechanism of action of STN-HFS is similar regardless of the cause of dystonia, our findings suggest that the STN is not similarly involved in off-period dystonia of IPD and others dystonias.

Unraveling the Hallervorden-Spatz syndrome: pantothenate kinase-associated neurodegeneration is the name.

PURPOSE OF REVIEW: After the recent discovery of the major genetic defect in neurodegeneration with brain iron accumulation (NBIA, formerly Hallervorden-Spatz syndrome), this heterogeneous group of disorders can now be differentiated by clinical, radiographic, and molecular features. RECENT FINDINGS: Disease caused by mutations in the gene encoding pantothenate kinase 2 (PANK2) is characterized by dystonia and pigmentary retinopathy in children or speech and neuropsychiatric defects in adults, in concert with a specific pattern on MRI of the brain. This virtually pathognomonic radiographic abnormality, called the eye-of-the-tiger sign, comprises hyperintensities within a hypointense medial globus pallidus on T2-weighted images. This disorder is called pantothenate kinase-associated neurodegeneration (PKAN) and accounts for most patients diagnosed with NBIA. Pantothenate kinase is essential to coenzyme A biosynthesis, and PANK2 is targeted to mitochondria, a feature that distinguishes it from the three other human pantothenate kinase homologs. Hypotheses of PKAN pathogenesis are based on the predictions of tissue-specific coenzyme A deficiency and the accumulation of cysteine-containing enzyme substrates, which may chelate iron and lead to the cardinal disease feature of basal ganglia iron accumulation. SUMMARY: Recent insight into the biochemical basis of PKAN has led to novel ideas for rational therapies. Investigations are under way to enable testing of promising compounds, first in animal models of disease and then in human patients. Identification of the genetic basis for the major form of NBIA has allowed more accurate clinical delineation of the specific diseases that compose this group, a new molecular diagnostic test for PKAN, and hypotheses for treatment of this neurodegenerative disorder.

Pantothenate kinase-associated neurodegeneration (Hallervorden-Spatz syndrome).

The arguments over the nomenclature of the syndrome are reviewed. Ethical considerations favour replacing the present eponyms with the title of panthothenate kinase-associated neurodegeneration (PKAN), now that more is known about the cause of the condition. The symptoms and signs of the syndrome are described, and these can present from infancy to adult life. Dystonia, involuntary movements and spasticity are prominent causes of disability. If the onset is delayed the presentation can be unusual. Tests that can help in diagnosis are reviewed, especially the "eye of the tiger" revealed by magnetic resonance imaging scanning. Death usually occurs about 10 years after the onset, but the course may be more prolonged. The findings on autopsy are also considered, with the typical findings of iron pigment deposits and axonal spheroids. Then the causes are discussed. Once the responsible gene PANK2 had been discovered on chromosome 20 it was found that this encoded for pantothenate kinase which is essential for the synthesis of coenzyme A from pantothenate; and this is integral to fatty acid synthesis and energy metabolism. Also this can lead to a concentration of cysteine in the basal ganglia, and then to an accumulation of iron in these areas. The cysteine-iron complex will result in tissue damage by promoting oxidative stress, as in some other neurodegenerative diseases. The syndrome of PKAN can therefore be identified as a disorder of pantothanate, vitamin B5, metabolism. Infantile neuroaxonal dystrophy is briefly described as there have been suggestions that it is a variety of PKAN, but the evidence is in favour of the two diseases being separate entities. There may as yet be no specific treatment for this syndrome, but much can be done to help these children. Drugs may be needed to control epilepsy, and when dystonia is severe it may be possible to alleviate this by medical or surgical means. Also there will be other problems needing expert management, such as the provision of alternative means of communication if dysarthria is marked. The hope for the future is that now the cause has been found it will be possible to use methods such as antioxidative therapy and gene induction procedures.

[Neurodegeneration with brain iron accumulation, type-I (NBIA-I) (formerly Hallervorden-Spatz, disease). Par I: clinical manifestation and treatment]. / Zwyrodnienie osrodkowego ukladu nerwowego z odkladaniem sie zelaza w mózgu, typu pierwszego (dawniej choroba Hallervordena-Spatza). Czesc i--obraz kliniczny oraz leczenie.

This is a rare syndrome, most likely of several genetically determined neurodegenerative disorders with similar pathogenesis. Two forms of the disease are distinguished: familial occurring in about 50% of cases and sporadic with about 15% of cases in which parental consanguinity is found. Clinically, NBIA-1 is characterised by a slow progression of extrapyramidal symptoms and progressive dementia, mostly in children. Relentlessly progressive course is obvious, but the progress may be very slow, taking sometimes several dozen of years. Four subtypes of the disease have been thus far distinguished: early childhood, late childhood, adult onset and with protracted course. The clinical diagnosis of NBIA-1 is only probable because specific abnormalities have not as yet been detected in laboratory investigations. However, NBIA-1 should be suspected, if extrapyramidal symptoms are observed, such as dystonia, choreoathetosis, muscular rigidity, moreover dementia, retinal degeneration and/or optic nerve atrophy and characteristic magnetic resonance imaging (so called "the eye-of-the tiger" sign). At present, only comprehensive symptomatic treatment is possible.