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Hereditary spastic paraplegias can be classified based on the symptoms; mode of inheritance; the patient’s age at onset; the affected genes; and biochemical pathways involved.
Clinical diagnosis is conducted on individuals with age onset between late teens and late forties who show the initial characteristics for the recessive autosomal cerebellar ataxia.
The following tests are performed:
- MRI brain screening for cerebellum atrophy.
- Molecular genetic testing for SYNE-1 sequence analysis.
- Electrophysiologic studies for polyneurotherapy
- Neurological examination
Prenatal diagnosis and preimplantation genetic diagnosis (PGD) can be performed to identify the mothers carrying the recessive genes for cerebellar ataxia.
Although HSP is a progressive condition, the prognosis for individuals with HSP varies greatly. It primarily affects the legs although there can be some upperbody involvement in some individuals. Some cases are seriously disabling while others are less disabling and are compatible with a productive and full life. The majority of individuals with HSP have a normal life expectancy.
Different types of ataxia:
- congenital ataxias (developmental disorders)
- ataxias with metabolic disorders
- ataxias with a DNA repair defect
- degenerative ataxias
- ataxia associated with other features.
Neuroimaging like MRI is important. However, there was considerable intrafamilial variability regarding neuroimaging, with some individuals showing normal MRI findings. Early individual prognosis of such autosomal recessive cerebellar ataxias is not possible from early developmental milestones, neurological signs, or neuroimaging.
While the clinical picture may point towards the diagnosis of the Roussy–Lévy syndrome, the condition can only be confirmed with absolute certainty by carrying out genetic testing in order to identify the underlying mutations.
Diffuse, symmetric white matter abnormalities were demonstrated by magnetic resonance imaging (MRI) suggesting that Behr syndrome may represent a disorder of white matter associated with an unknown biochemical abnormality.
In 1993, Peter James Dyck divided HSAN I further into five subtypes HSAN IA-E based on the presence of additional features. These features were thought to result from the genetic diversity of HSAN I (i.e. the expression of different genes, different alleles of a single gene, or modifying genes) or environmental factors. Molecular genetic studies later confirmed the genetic diversity of the disease.
Diagnosis is suspected clinically and family history, neuroimaging and genetic study helps to confirm Behr Syndrome.
The diagnosis of HSAN I is based on the observation of symptoms described above and is supported by a family history suggesting autosomal dominant inheritance. The diagnosis is also supported by additional tests, such as nerve conduction studies in the lower limbs to confirm a sensory and motor neuropathy. In sporadic cases, acquired neuropathies, such as the diabetic foot syndrome and alcoholic neuropathy, can be excluded by the use of magnetic resonance imaging and by interdisciplinary discussion between neurologists, dermatologists, and orthopedics.
The diagnosis of the disease has been revolutionized by the identification of the causative genes. The diagnosis is now based on the detection of the mutations by direct sequencing of the genes. Nevertheless, the accurate phenotyping of patients remains crucial in the diagnosis. For pregnant patients, termination of pregnancy is not recommended.
HSAN I must be distinguished from hereditary motor and sensory neuropathy (HMSN) and other types of hereditary sensory and autonomic neuropathies (HSAN II-V). The prominent sensory abnormalities and foot ulcerations are the only signs to separate HSAN I from HMSN. HSAN II can be differentiated from HSAN I as it is inherited as an autosomal recessive trait, it has earlier disease onset, the sensory loss is diffused to the whole body, and it has less or no motor symptoms. HSAN III-V can be easily distinguished from HSAN I because of congenital disease onset. Moreover, these types exhibit typical features, such as the predominant autonomic disturbances in HSAN III or congenital loss of pain and anhidrosis in HSAN IV.
Genetic testing is necessary to identify the syndrome. The DNA test is necessary sometimes because symptoms may not be sufficient to definitely diagnose this condition.
In diagnosing autosomal dominant cerebellar ataxia the individuals clinical history or their past health examinations, a current physical examination to check for any physical abnormalities, and a genetic screening of the patients genes and the genealogy of the family are done. The large category of cerebellar ataxia is caused by a deterioration of neurons in the cerebellum, therefore magnetic resonance imaging (MRI) is used to detect any structural abnormality such as lesions which are the primary cause of the ataxia. Computed tomography (CT) scans can also be used to view neuronal deterioration, but the MRI provides a more accurate and detailed picture.
Brain MRI shows vermis atrophy or hypoplasic. Cerebral and cerebellar atrophy with white matter changes in some cases.
The inheritance pattern is autosomal recessive. The disorder is caused by a mutation in the SGCG on chromosome 13. The mutation of the SACS gene causes the production of an unstable, poorly functioning SACSIN protein. It is unclear as to how this mutation affects the central nervous system (CNS) and skeletal muscles presenting in the signs and symptoms of ARSACS.
Between this condition and NF-1 an important difference is the absence of tumor growths (Lisch nodules and neurofibromas which are common in NF-1) in LS.
The symptoms of Legius syndrome and NF-1 are very similar, this is the reason why the two are easily confused. A genetic test is often the only way to make sure a person has LS and not NF-1,
the similarity of symptoms stem from the fact that the different genes affected in the two syndromes code for proteins that carry out a similar task in the same reaction pathway.
Prenatal screening is not typically done for FHM, however it may be performed if requested. As penetrance is high, individuals found to carry mutations should be expected to develop signs of FHM at some point in life.
There is no known prevention of spinocerebellar ataxia. Those who are believed to be at risk can have genetic sequencing of known SCA loci performed to confirm inheritance of the disorder.
Physical therapy is the predominant treatment of symptoms. Orthopedic shoes and foot surgery can be used to manage foot problems.
There is no known prevention of spinocerebellar ataxia. Those who are believed to be at risk can have genetic sequencing of known SCA loci performed to confirm inheritance of the disorder.
Most patients begin to use a wheelchair for movement around age 30-40. Death usually occurs in their 60s, but some have been reported to live longer.
To gain a better understanding of the disease, researchers have retrospectively reviewed medical records of probands and others who were assessed through clinical examinations or questionnaires. Blood samples are collected from the families of the probands for genetic testing. These family members are assessed using their standard medical history, on their progression of Parkinson's like symptoms (Unified Parkinson's Disease Rating Scale), and on their progression of cognitive impairment such as dementia (Folstein Test).
In terms of a cure there is currently none available, however for the disease to manifest itself, it requires mutant gene expression. Manipulating the use of protein homoestasis regulators can be therapuetic agents, or a treatment to try and correct an altered function that makes up the pathology is one current idea put forth by Bushart, et al. There is some evidence that for SCA1 and two other polyQ disorders that the pathology can be reversed after the disease is underway. There is no effective treatments that could alter the progression of this disease, therefore care is given, like occupational and physical therapy for gait dysfunction and speech therapy.
40 cases were diagnosed in northern Italy between 1940 and 1990. The gene frequency for this autosomal recessive condition was estimated at 1 in 218. In 1989, 16 cases on EOCA were diagnosed in children with a mean onset age of 7.1 In 1990, 20 patients affected by EOCA were studied. It was found that the ataxia of this study's participants affected the pyramidal tracts and peripheral nerves.
Standard MRI scans have been performed on 1.5 Tesla scanners with 5 mm thickness and 5 mm spacing to screen for white matter lesions in identified families. If signal intensities of the MRI scans are higher in white matter regions than in grey matter regions, the patient is considered to be at risk for HDLS, although a number of other disorders can also produce white matter changes and the findings are not diagnostic without genetic testing or pathologic confirmation.
The long-term prognosis of Costeff syndrome is unknown, though it appears to have no effect on life expectancy at least up to the fourth decade of life. However, as mentioned previously, movement problems can often be severe enough to confine individuals to a wheelchair at an early age, and both visual acuity and spasticity tend to worsen over time.