Restless legs syndrome in hereditary spastic paraparesis

This study was designed to investigate the prevalence and determinants of the association of restless legs syndrome (RLS) and hereditary spastic paraparesis (HSP). Therefore, 132 patients with HSP were evaluated concerning the symptoms of RLS by a standardized questionnaire. RLS was supposed when patients met all of the established four essential criteria of RLS defined by the International RLS Study Group. In addition, we studied the relationship between RLS and age at HSP symptom onset and evaluated the severity of RLS symptoms. Out of 59 responses, RLS was found in 27 HSP patients (15 male, 12 female) so that RLS was more frequent in the total HSP group (20.5%; 27/132) than in previous population-based studies (about 11%). In all 27 patients, the diagnosis of RLS was established based on an additional personal interview. The probability to develop RLS did not increase with higher age. Age at onset of HSP symptoms in the HSP group with RLS (27.7 +/- 12.6 years) and the HSP group without RLS (37.0 +/- 16.9 years) differed significantly (p = 0.04). Most of the patients with RLS showed a moderate and severe grade on the RLS severity score. Only 8 patients had previously been diagnosed to have RLS and were on medication. The data of this screening for RLS provided evidence that patients with HSP are particularly susceptible to develop RLS. Consequently, special emphasis should be put on the diagnosis criteria of RLS in HSP patients.     

Investigation of mitochondrial function in hereditary spastic paraparesis

Following the association of hereditary spastic paraparesis (HSP) with mutation in the paraplegin gene (SPG7) and mitochondrial dysfunction, we wished to investigate whether mitochondrial dysfunction might be associated with other forms of HSP. Five cases of HSP caused by mutation in the spastin gene (SPG4) and nine cases with HSP with mutation in the spastin and paraplegin genes excluded (non-SPG4/SPG7), were investigated for mitochondrial dysfunction. Muscle tissue from the HSP groups and a control group was analysed histochemically and spectrophotometrically for mitochondrial dysfunction. A significant decrease in mitochondrial respiratory chain complexes I and IV was demonstrated in the non-SPG4/SPG7 group. No abnormality was detected in the SPG4 group. We therefore conclude that there is evidence for mitochondrial dysfunction in non-SPG4/SPG7 HSP. There is no evidence for mitochondrial dysfunction in the pathogenesis of spastin-related HSP.     

Transcranial magnetic stimulation study in hereditary spastic paraparesis

The motor-evoked potentials and the cortical excitability by transcranial magnetic stimulation (TMS) were studied in a family with chromosome 2p linked (due to mutations in spastin) and in a family with chromosome 16q linked (due to mutations in paraplegin) hereditary spastic paraparesis (HSP), in order to evaluate the utility of these techniques in identifying the subgroups of the disease. Central motor conduction time and motor treshold to TMS were abnormal in some members of both families; the intracortical inhibition was reduced only in the affected members of the family with chromosome 2p linked HSP, even though the neurological symptoms were sometimes similar and also when clinical features reflecting cortical dysfunction were absent. The motor cortex is differentially involved in the often clinically indistinguishable forms of HSP, and TMS may help in the differential diagnosis.     

Botulinum toxin injection in patients with hereditary spastic paraparesis

In an open label study, we analyzed the efficacy of botulinum toxin injection at the lower limbs of patients with hereditary spastic paraparesis (HSP). Fifteen patients who showed disabling spasticity with no or poor effect of oral treatment were recruited consecutively. Botulinum toxin was injected (400 U; Botox^®) into the spastic muscles identified by clinical examination (equinus, varus, and pathological hip adduction). Patients were regularly assessed from the first day to the fifth month: spasticity (Ashworth), motor strength, range of movements, Functional Ambulation Categories (FAC), gait parameter, Rivermead Motor Assessment, self-analysis of benefit and satisfaction. We observed a moderate and significant ( P  < 0.05) reduction of ankle plantar flexor and hip adductor spasticity, with a partial increase in the range of the active and passive motion at the ankle and in gait velocity. At an individual level, six of 15 patients showed an increase in gait velocity. The FAC and RMA did not change. Patients often reported partial improvement in foot position and lower limb propulsion, and fair satisfaction. In conclusion, botulinum toxin injection can be effective in HSP patients with relatively ancient spasticity. This technique can be introduced into the therapeutic panel, which also includes physiotherapy, oral treatment and baclofen pump.     

Clinical and genetic update of hereditary spastic paraparesis

Hereditary spastic paraparesis is a group of inherited neurological diseases characterized by underlying wide genetic heterogeneity. It should be suspected if there is a positive familial history, a common genetic alteration (i.e. SPG4, the most overall frequent form), or association with other signs, such as cerebellar ataxia (i.e. SPG7), early cognitive impairment or even cognitive deficit (i.e. SPG11), or peripheral neuropathy (i.e. SACS). The natural history is known for certain genetic subgroups, with genotype-phenotype correlations partially explaining childhood or late onset. However, the search for genetic modifying factors, in addition to the causal pathogenic variant or environmental influencers, is still needed. Novel approaches to provide etiological treatment are in the pipeline for SPG11. Symptomatic treatments are available but would benefit from randomized controlled trials.     

Functional changes of the cortical motor system in hereditary spastic paraparesis

Background – Hereditary spastic paraparesis (HSP) is a heterogeneous group of disorders characterized by progressive bilateral lower limb spasticity. Functional imaging studies in patients with corticospinal tract involvement have shown reorganization of motor circuitry. Our study investigates functional changes in sensorimotor brain areas in patients with HSP. Methods – Twelve subjects with HSP and 12 healthy subjects were studied. Functional magnetic resonance imaging (fMRI) was used to measure brain activation during right‐hand finger tapping. Image analysis was performed using general linear model and regions of interest (ROI)‐based approach. Weighted laterality indices (wLI) and anterior/posterior indicies (wAI and wPI) were calculated for predefined ROIs. Results and discussion – Comparing patients and controls at the same finger‐tapping rate (1.8 Hz), there was increased fMRI activation in patients’ bilateral posterior parietal cortex and left primary sensorimotor cortex. No differences were found when comparing patients and controls at 80% of their individual maximum tapping rates. wLI of the primary sensorimotor cortex was significantly lower in patients. Subjects with HSP also showed a relative increase in the activation of the posterior parietal and premotor areas compared with that of the primary sensorimotor cortex. Our findings demonstrate an altered pattern of cortical activation in subjects with HSP during motor task. The increased activation probably reflects reorganization of the cortical motor system.     

Hand muscles corticomotor excitability in hereditary spastic paraparesis type 4

Transcranial magnetic stimulation (TMS) studies on the pathways to the upper limbs have revealed inconsistent results in patients harboring mutations in SPAST/SPG4 gene, responsible for the commonest form of hereditary spastic paraplegia (HSP). This paper is addressed to study the corticomotor excitability of the pathways to the upper limbs in SPG4 subjects. We assessed the corticomotor excitability of hand muscles in 12 subjects belonging to 7 unrelated SPG4 families and in 12 control subjects by stimulus–response curve [input–output (I–O) curve]. All the parameters of the recruitment curve (threshold, V50, slope and plateau) did not differ significantly from those of the controls. Presence of upper limb hyper-reflexia did not influence the results of I–O curve. Considering the multiplicity of possible genes/loci accounting for pure HSPs, performing TMS analyses could be helpful in differential diagnosis of pure HSPs in the absence of other clinical or neuroimaging tools.     

Three novel mutations in 20 patients with hereditary spastic paraparesis

Hereditary spastic paraparesis (HSP) constitutes both genetic and clinically heterogeneous group of upper motor neuron diseases. Half of the individuals with autosomal dominant (AD) HSP have mutations in SPAST, ATL1, and REEP1 genes. This study was conducted to elucidate the genetic etiology of patients with the pure type AD-HSP diagnosis. The patient group consisted of 23 individuals from 6 families in Turkey. In the first step of work, Sanger sequencing (SS) was performed in ATL1, SPAST, and REEP1 genes and the second phase whole-exome sequencing (WES) was performed following SS analysis for the patients with no detected mutations in these genes. The results of this study revealed that in ATL1, 6 patients have previously reported c.776C?>?A mutation and 6 patients have novel c.470 T?>?C mutation. In SPAST, 3 patients have novel c.1072G?>?C mutation and 2 patients have novel c.1099-1G?>?C mutation. WES was performed in three patients, who had no detected mutation in these genes with SS analysis. In this approach, as previously reported c.1859 T?>?C mutation in KIAA0196 was detected, and it was confirmed with the patient’s relatives by SS. In three of patients, no HSP-associated variant could be identified in SS and WES. With this study, the molecular genetic etiology in 20 of 23 (87%) individuals that were included in this study with the utilization of SS and WES was elucidated. Utilization of SS and WES methods have enabled the identification of genetic etiology of HSP further with appropriate genetic counseling that was provided to the patients.     

Infantile hereditary spastic paraparesis due to codominant mutations in the spastin gene

The authors describe an infant with a severe spastic paraparesis caused by two codominant mutations of the spastin gene. This highlights the multiple molecular mechanisms that are likely to be involved in the molecular pathology of SPG4 and illustrates the importance of complete screening of the spastin gene in affected individuals, particularly if the index case has an unusual phenotype.     

Clinical and pathologic findings in hereditary spastic paraparesis with spastin mutation

OBJECTIVE: To describe a family with chromosome 2p-linked hereditary spastic paraparesis (HSP) associated with dementia and illustrate the cerebral pathology associated with this disorder. BACKGROUND: HSP comprises a heterogeneous group of inherited disorders in which the main clinical feature is severe, progressive lower limb spasticity. Nongenetic classification relies on characteristics such as mode of inheritance, age at onset, and the presence or absence of additional neurologic features. Several loci have been identified for autosomal dominant pure HSP. The most common form, which links to chromosome 2p (SPG4), has recently been shown to be due to mutations in spastin, the gene encoding a novel AAA-containing protein. RESULTS: The authors report four generations of a British family with autosomal dominant HSP in whom haplotype analysis indicates linkage to chromosome 2p. In addition, a missense mutation has been identified in exon 10 of the spastin gene (A1395G). Dementia was documented clinically in one member of the family, two other affected family members were reported to have had late onset memory loss, and a younger affected individual showed evidence of memory disturbance and learning difficulties. Autopsy of the demented patient confirmed changes in the spinal cord typical of HSP and also demonstrated specific cortical pathology. There was neuronal depletion and tau-immunoreactive neurofibrillary tangles in the hippocampus and tau-immunoreactive balloon cells were seen in the limbic and neocortex. The substantia nigra showed Lewy body formation. The pathologic findings are not typical of known tauopathies. CONCLUSIONS: The authors confirm that chromosome 2p-linked HSP can be associated with dementia and that this phenotype may be associated with a specific and unusual cortical pathology.     

X-linked adrenoleukodystrophy presenting as autosomal dominant pure hereditary spastic paraparesis

We present a family in which an initial clinical diagnosis of autosomal dominant pure hereditary spastic paraparesis (HSP) was made on the basis of a three generation pedigree in which both males and females presented with a spastic paraparesis. Subsequent biochemical and genetic analysis revealed that the family was in fact affected by the adrenomyeloneuropathy subtype of X-linked adrenoleukodystrophy. In the family described, both males and females were affected by a spastic paraparesis, and there was no male to male transmission, consistent with both autosomal dominant and X-linked inheritance. This report illustrates the importance of assaying very long chain fatty acids (VLCFAs) in any HSP family where there is no male to male transmission.     

Long-term results of selective dorsal rhizotomy for hereditary spastic paraparesis

Pure hereditary spastic paraparesis usually presents with progressive weakness and spasticity of the legs, which is similar to spastic cerebral palsy. In this study selective dorsal rhizotomy (SDR) was performed to improve the spasticity of pure hereditary spastic paraparesis and the long-term results were followed. A series of four patients with pure hereditary spastic paraparesis diagnosed by a multidisciplinary team received SDR. The dorsal rootlets from the L2 to S1 levels were selectively resected under electrophysiological monitoring. The patients were followed up for more than 2 years to evaluate the outcome of surgery. There was a significant reduction in muscular spasm after SDR. Standing and walking stability were improved in all patients which led to improvement in walking posture and longer walking distance without assistance. No urinary retention, cerebrospinal fluid leak, surgical infection or kyphosis occurred. For severe pure hereditary spastic paraparesis, SDR can reduce muscle spasm and improve standing and walking stability. These results were stable throughout follow-up. SDR performed at the level of the conus medullaris through a laminectomy from T12 to L1 or L1 to L2 requires a shorter incision, laminectomy of fewer segments, and has a shorter operation time than the usual method (laminectomy from L2 to S1). Intraoperative electrophysiological monitoring is helpful to discriminate abnormal rootlets and protect sphincter function.     

Age-related cognitive decline in hereditary spastic paraparesis linked to chromosome 2p

OBJECTIVES: To investigate whether cognitive decline is part of the phenotype of SPG4-linked hereditary spastic paraparesis (HSP) and to determine whether cognitive changes are present in haplotype carriers before the onset of paraparesis. BACKGROUND: The major locus for "pure" autosomal dominant HSP is the SPG4 locus on chromosome 2p. Cognitive impairment linked to this locus has been described in two families. METHODS: The authors identified 19 families with "pure" autosomal dominant HSP. Five had linkage to the SPG4 locus (maximum lod score for D2S2374: 5.99 at zero recombination in four smaller families and 3.86 at zero recombination in the largest family). Haplotype construction identified a disease haplotype for all families; 41 individuals carried this haplotype (30 affected by HSP, 11 unaffected). All haplotype carriers and 41 matched controls underwent Cambridge Cognitive (CAMCOG) examination. Nonparametric significance tests were used comparing total and subset scores. RESULTS: Haplotype carriers affected by HSP had lower total CAMCOG scores than control subjects (85.86/107 versus 96.2/107; p < 0.0005). The subsets of orientation, memory, language expression, and comprehension were also significantly lower. Ten individuals had scores < or =80/107, indicating mild dementia. Unaffected haplotype carriers had mean total CAMCOG scores lower than control subjects (91.82/107 versus 98. 09/107; p = 0.016). In both groups cognitive decline was age-dependent and scores diverged from control subjects from age 40. All SPG4-linked families showed the effect. CONCLUSION: Mild, age-related cognitive impairment is a feature common to these families. It illustrates variable phenotypic expression at this locus and may be the first manifestation of the disease gene in individuals as yet unaffected by paraparesis.     

The prevalence of "pure" autosomal dominant hereditary spastic paraparesis in the island of Ireland.

OBJECTIVES: Hereditary spastic paraparesis (HSP) is clinically and genetically heterogeneous. "Pure" autosomal dominant (AD) HSP is most common and eight genetic loci are identified to date. Previous studies have included autosomal recessive and sporadic cases in prevalence calculations. This study aimed to determine the prevalence and features of pure ADHSP in the island of Ireland. METHODS: Index cases were identified from a 5 year survey of all adult and paediatric neurologists, clinical geneticists, hospital records, and hospital inpatient enquiry system data in Ireland, north and south. Families were examined by two neurologists and classified as affected or unaffected according to specific criteria. The prevalence date was set at 1 June 2000 and the midyear population estimate for the previous year was 5.436 million. RESULTS: Eighty two patients with pure ADHSP and a further 12 obligate carriers from 19 families were identified. In total 69 patients with pure ADHSP were alive and resident in Ireland at the prevalence date. Twenty nine per cent of these were asymptomatic but with signs of paraparesis. CONCLUSIONS: The prevalence of ADHSP in Ireland to estimated to be 1.27/100 000 population. The high proportion of asymptomatic cases and obligate carriers means that this condition is likely to be underdiagnosed.     

Autosomal recessive hereditary spastic paraparesis with thin corpus callosum; report of two sisters.

OBJECTIVES: To describe the clinical, cognitive, neurophysiological and radiological features of autosomal recessive hereditary spastic paraparesis (ARHSP) with thin corpus callosum. PATIENTS AND METHODS: Two sisters with spastic paraparesis. RESULTS: MRI brain scans demonstrated thinning of the corpus callosum. The clinical features were progressive spastic paraparesis beginning in the second decade, dysarthria, minor dystonia and chorea, distal weakness and cognitive impairment with frontal dysfunction. Motor compound action potentials are reduced and EMG demonstrated minor chronic denervation. Magnetic stimulation studies demonstrated increased threshold consistent with pyramidal system axonal loss. CONCLUSIONS: AHRSP with thinned corpus callosum is a distinct clinical and genetic entity that may occur in non-Japanese individuals.     

Paraplegin gene analysis in hereditary spastic paraparesis (HSP) pedigrees in northeast England

OBJECTIVE: To identify the frequency and characterize the phenotype of paraplegin mutations in the hereditary spastic paraparesis (HSP) population in the northeast of England. BACKGROUND: HSP is a disorder that shows both clinical and genetic heterogeneity. To date, 13 loci have been associated with an HSP phenotype, with the causative gene having been identified in four of these. Two autosomal genes have been identified, paraplegin and spastin, and two X-linked genes have been identified, L1CAM (cell adhesion molecule) and proteolipid protein. METHODS: Thirty HSP pedigrees from the northeast of England were analyzed for mutation in each of the 17 exons of the paraplegin gene. RESULTS: A single family with a paraplegin mutation was identified in which the paraplegin mutation co-segregates with an HSP phenotype in an apparent dominant manner. The authors also describe frequent polymorphism in the paraplegin gene in both the HSP and control populations. CONCLUSION: Mutations in the paraplegin gene are not a common cause of HSP in the northeast of England. The phenotype of the paraplegin-related HSP family described had several striking features including amyotrophy, raised creatine kinase, sensorimotor peripheral neuropathy, and oxidative phosphorylation defect on muscle biopsy.     

Magnetic resonance investigation of the upper spinal cord in pure and complicated hereditary spastic paraparesis

Neuropathological studies of hereditary spastic paraparesis (HSP) have described axonal loss involving corticospinal and somatosensory tracts in the spinal cord. This MRI-based study was intended to investigate in vivo diameter alterations of the spinal cord in HSP, including both pure HSP (p-HSP, n = 20) and complicated HSP (c-HSP, n = 10). Standard MRI examinations of the cervical and thoracic spinal cord in HSP patients and a control group (n = 54) were analyzed by standardized spinal cord planimetry. In HSP patients, significant atrophy of the upper spinal cord compared to controls was observed at p < 0.001 both at the cervical and at the thoracic level. Myelon diameters at both levels were also significantly reduced in the two HSP subgroups in an additional comparison with age-matched subgroups of controls each, but p-HSP and c-HSP groups themselves did not differ. Marked atrophy of the upper spinal cord seems to be associated with HSP, assumedly due to the central-distal axonopathy. However, the differences between p-HSP and c-HSP could not be visualized by structural MRI at spinal cord level.