Hirosei Horikawa

Spinocerebellar ataxia type 6 Molecular and clinical features of 35 Japanese patients including one homozygous for the CAG repeat expansion

Spinocerebellar ataxia type 6 (SCA6) is a newly classified autosomal-dominant cerebellar ataxia (ADCA) associated with CAG repeat expansion. We screened 111 patients with cerebellar ataxia for the SCA6 mutation. Of these, 35 patients were found to have expanded CAG repeats in the SCA6 gene, indicating that second to SCA3, SCA6 is the most common ADCA in Japan. Expanded alleles ranged from 21 to 29 repeats, whereas normal alleles had seven to 17 repeats. There was no change in the CAG repeat length during meiosis. The age at onset was inversely correlated with the repeat length. The main clinical feature of the 35 patients with SCA6 was slowly progressive cerebellar ataxia; multisystem involvement was not common. The 35 patients included nine cases without apparent family history of cerebellar ataxia. The sporadic cases had smaller CAG repeats (21 or 22 repeats) and a later age at onset (64.9 ± 4.9 years) than the other cases with established family history. We also identified one patient who was homozygous for the SCA6 repeat expansion. The homozygote showed an earlier age of onset and more severe clinical manifestations than her sister, a heterozygote carrying an expanded allele with the same repeat length as the homozygote. This finding suggests that the dosage of the CAG repeat expansion plays an important role in phenotypic expression in SCA6.

CAG repeat expansions in patients with sporadic cerebellar ataxia

CAG repeat expansions cause spinocerebellar ataxia type 1 (SCA1), SCA2, SCA3, SCA6 and dentatorubral‐pallidoluysian atrophy (DRPLA). So far these expansions have been examined mainly in ataxia patients with a family history. However, some sporadic cases with SCA have recently been reported. To elucidate the frequency and characteristics of sporadic SCAs, we screened 85 Japanese ataxia patients without a family history for the SCA1, SCA2, SCA3, SCA6 and DRPLA mutations. As a result, 19 patients (22%) were found to have expanded CAG repeats. Among sporadic SCAs, the SCA6 mutation was most frequently observed. The sporadic SCA6 patients had smaller CAG repeats and a later age of onset than SCA6 patients with an established family history. We also identified one father‐child pair in which intermediate sized CAG repeats expanded into the SCA2 disease range during transmission. These findings suggest that patients with ataxia even without a family history should be examined for a CAG repeat expansion.

The relationship between trinucleotide repeat length and phenotypic variation in Machado-Joseph disease

Trinucleotide repeat expansion in the Machado-Joseph disease (MJD) gene has been found in 26 patients from 20 unrelated Japanese families. Expanded alleles had 68 to 84 repeats, whereas normal alleles had 14 to 37 repeats. The age of onset was inversely correlated with the repeat length. To evaluate in detail the relationship between the repeat length and clinical features, we subdivided the 26 patients into three groups on the basis of the repeat length (group 1, 78 repeats or more; group 2, 74 to 77 repeats; group 3, 73 repeats or less). Group 1 and group 2 had common features of spasticity, hyperreflexia, Babinski sign, bulging eyes, facial myokymia and extrapyramidal signs as well as cerebellar ataxia and ophthalmoplegia. It should be noted that group 1 showed more prominent pyramidal and extrapyramidal signs than group 2. In contrast, group 3 showed hypotonia, hyporeflexia and sensory disturbance in addition to cerebellar ataxia and ophthalmoplegia. These findings suggest that the repeat length plays an important role in phenotypic variation. DNA analysis for the MJD mutation was clearly useful for making an accurate diagnosis in patients without bulging eyes, facial myokymia, dystonia or marked spasticity.

Isolated inflammatory myopathy with rimmed vacuoles presenting with dropped head

We describe an unusual case of inflammatory myopathy with rimmed vacuoles associated with dropped head syndrome. Muscle biopsy in our patient revealed variations in fiber size with fiber necrosis and regeneration, accompanied by many rimmed vacuoles and areas of endomysial cell infiltration. Electron microscopy demonstrated autophagic vacuoles and tubulofilamentous inclusions. This myopathy can cause dropped head syndrome in a subgroup of patients.

Clinical analysis and outcomes of amyotrophic lateral sclerosis with demyelinating polyneuropathy

Abstract Abnormalities of both motor and sensory nerve action potentials, similar to those found in demyelinating polyneuropathy, may occur in patients with amyotrophic lateral sclerosis (ALS). We analyzed the clinical features of unusual ALS patients with demyelinating polyneuropathy (DPN) to delineate the characteristics and outcomes of this rare condition. We reviewed three ALS patients with DPN who were confirmed to meet the electrophysiological nerve conduction criteria for DPN among 157 patients with ALS. At the initial neurological examination, one patient had both subjective sensory symptoms and abnormal results of sensory examinations, and one patient had sensory symptoms. Motor weakness of the limbs was present in all patients, and fasciculation was present in two patients. Anti-GalNAc-GD1a IgG antibodies were evident in one. Sural nerve biopsy showed a moderate, marginal reduction in myelin thickness, and teased fiber analysis revealed segmental demyelination and remyelination, but axonal degeneration was found in one patient. The mean interval from disease onset to respiratory failure or death in our three patients and seven previously documented ALS patients with DPN was 43.1 ± 18.7 months. Our findings suggest that survival in ALS with DPN is similar to that in classic ALS.

Preoperative Low-Dose Steroid Can Prevent Respiratory Insufficiency After Thymectomy in Generalized Myasthenia Gravis

Background: Postoperative respiratory insufficiency (PRI) in myasthenia gravis (MG) often occurs within several days after thymectomy and remains problematic. In limited studies reporting that preoperative steroids prevented PRI in patients with MG, high doses of steroids were used and detailed information on the use of steroids is limited. Because high-dose steroids significantly increase the risk of adverse effects, we studied 37 patients with generalized MG to investigate whether low-dose steroids might prevent PRI. Methods: The low-dose steroids were started orally, and the dose was gradually increased to the maximum level (30 mg/day). Immediately before thymectomy, patients received the maximum dose of oral steroids daily. PRI was defined as the development of restrictive dysfunction requiring mechanical ventilation within 3 days after thymectomy and total postoperative mechanical ventilation support time of >24 h. Results: The rate of PRI in the low-dose steroid use group was significantly lower than that in the no-steroid use group. The postoperative stay in the intensive care unit was shorter in the steroid use group. Conclusions: Extended thymectomy is a well-accepted surgical treatment for selected patients with MG. However, PRI remains problematic. Our results suggest that not only preoperative high-dose steroid treatment, but also low-dose steroid treatment can prevent PRI.

Paradoxical Gait at a Narrowed Entrance in a Patient with Hoehn-Yahr Stage III Parkinson’s Disease

Recently, we studied fallers and non-fallers with Hoehn-Yahr stage III Parkinson’s disease (PD) using a path that suddenly narrowed, which we originally designed and produced. A risk of future falls was suggested to be related to slow gait with freezing (SGF) elicited by a fear of falling before arrival at a narrowed entrance or while walking on a narrow path, as well as to the Unified Parkinson’s Disease Rating Scale part II score, associated with SGF. In the same study, we had faller patients walk on a path that narrowed in a straight-line fashion to determine whether SGF could be improved. In one patient, who showed a unique paradoxical gait, SGF resolved. We describe this patient in the hope that our experience will provide potential clues to effective ways to prevent future falls in patients with Hoehn-Yahr stage III PD. To prevent gait instability elicited by fear of falling in patients with Hoehn-Yahr stage III PD, it might be useful to remove narrowed entrances.

Upper motor neuron involvement and conventional diffusion weighted imaging

Dear SirA 58-year-old female had symmetric spasticity,hyperreflexia, extensor plantar responses, spasticdysarthria, and pseudobulbar symptoms. The uppermotor neuron involvement had progressed graduallyover more than five years, leading to weakness in allfour limbs and pseudobulbar symptoms, requiring apercutaneous endoscopic gastrostomy. Denervationpotentials were not detectable on needle electro-myography. Primary lateral sclerosis was diagnosedclinically. Cranial magnetic resonance imagingshowed hyperintensity along the corticospinal tracts(CST) on fluid-attenuated inversion recovery(FLAIR) (Figure 1A) and T2-weighted images,with high signal intensity in the CST on diffusion-weighted imaging (DWI) (Figure 1B).High signal intensity was evident in the CST onDWI, extending from the precentral gyrus andpassing through the centrum semiovale, periventri-cular white matter, internal capsule, and brainstem.A single case of amyotrophic lateral sclerosis inwhich motor tract degeneration was highlightedmildly on DWI of recent lesions has been documen-ted (1). FLAIR images showed that abnormalitiesextended beyond the CST and were therefore notdiagnostic (1), whereas DWI images in our patientshowed abnormalities restricted to the CST. Becausechanges on DWI may be related to T2 abnormalities(‘T2 shine-through’), it would have been helpful ifsome FLAIR images had been obtained at the samelevels as the DWI images, thereby confirming uppermotor neuron disease.Reference

Cerebral Sinus and Venous Thrombosis Associated with von Willebrand Factor, Independently of Factor VIII

Background and purpose Previous studies have linked procoagulant factor VIII (F VIII) to an increased risk of venous thrombosis, whereas the relation between plasma von Willebrand factor (VWF) and venous thrombosis remains poorly understood. Elevated VWF levels are frequently found in patients with cerebral sinus and venous thrombosis (CSVT), always in association with high F VIII levels. We describe a patient with CSVT accompanied by elevated VWF levels without high F VIII levels. Case description A 23-year-old healthy man who had headache noticed difficulty in moving the right hand. On the following day, he lost consciousness and had partial seizures of the right hand. After regaining consciousness, weakness of the right extremities developed. The cranial angiogram confirmed occlusion of the superior sagittal sinus. The levels of VWF and F VIII were 238% and 101.9 IU/dl, respectively. We performed balloon percutaneous transluminal angioplasty and mechanical thrombectomy, leading to successful recanalization of the intracranial sinuses. VWF levels were decreased along with radiographic improvement, independently of F VIII. Conclusion VWF may contribute to CSVT and that inhibition of VWF activity potentially has a role in the future treatment of pathological conditions related to venous thrombosis.