A new method to define cutoff values in nerve conduction studies for carpal tunnel syndrome considering the presence of false-positive cases.

BACKGROUND: Nerve conduction studies (NCS) are useful tools for diagnosing carpal tunnel syndrome (CTS). Establishing the normal values is the first step required for utilizing NCS for diagnosis. Previous epidemiological studies demonstrated the presence of fairly large number of false-positive subjects regarding NCS among control population, which has not been properly considered in past studies. This study proposed a new method to address this issue. METHODS: Non-diabetic 144 CTS patients were retrospectively enrolled using clinically defined inclusion criteria. Controls consisted of 73 age-matched volunteers without hand symptoms. Six NCS parameters were evaluated including peak-latency difference by the thumb method (thumbdif) and that by the ring-finger method (ringdif). The Youden index of the receiver operator characteristic curve was used both to judge the sensitivity of a parameter and to identify false-positive cases that were thought to have subclinical median neuropathy at the wrist. The linear function of six parameters was constructed, and the coefficient for each parameter was variously changed. RESULTS: When the Youden index took on the maximum value, seven control subjects (10%) were identified as false-positive and were excluded from the calculation of normal values. The most sensitive parameter before exclusion was thumbdif, whereas ringdif became the most sensitive after exclusion. The cut-off value for ringdif was 1.15 ms before exclusion, but was 0.37 ms after exclusion. CONCLUSION: This method can be widely applied to solve the statistical problem when the gold standard is lacking, and the outside reference standard is not completely reliable.

Oculopharyngeal muscular dystrophy associated with dementia.

We report genetically confirmed heterozygote oculopharyngeal muscular dystrophy (OPMD) accompanied by dementia, suggesting a possible causal association between OPMD and dementia. The proband first noticed bilateral ptosis, dysphagia, and proximal dominant muscle weakness in the lower extremities at age 53. Ten years later, she was found to have dementia with a score of 10/30 on the mini-mental state examination (MMSE). On PABPN1 gene analysis, the GCN repeat was expanded 17 times in one allele. In addition, the proband's younger brother exhibited myopathy and dementia. To our knowledge, this is the first report of genetically confirmed heterozygote OPMD associated with dementia.

[A case of elderly-onset sarcoid myopathy with features resembling polymyositis].

A 75-year-old woman was admitted with a history of acute muscle weakness of her legs for two weeks. Physical examination showed no abnormal findings. Neurological examination revealed symmetrical proximal muscle weakness of legs with muscle pain on grasping. Laboratory data showed normal serum creatine kinase level and marked increases in the levels of serum ACE and soluble interleukin 2. Electromyography showed no myopathic changes. MRI T2 weighted imaging (T2WI) imaging for femoral skeletal muscle demonstrated scattered high and low intensity signals. Muscle biopsy from the right rectus femoris muscle showed granuloma with giant cells of Langhans. She was given a diagnosis of sarcoid myopathy, and motor weakness and abnormal intensity signals on T2WI in this patient were dramatically improved with oral administration of prednisolone (40 mg/day).

[Case of juvenile myoclonic epilepsy misdiagnosed as simple partial seizure for more than 60 years].

A 77-years-old woman was admitted to our hospital due to uncontrolled myoclonus and generalized seizure. Since the age of 17, she has been suffering from myoclonic jerks and partial convulsions in her right arm. Administration of several unknown anticonvulsants had not alleviated her condition. She was able to spend her life without a handicap, except for the symptoms described above. She has been experiencing psychological stress since the age of 50, which has resulted in worsening of her symptoms, and she was prescribed phenytoin, carbamazepine, and phenobarbital, which were also ineffective. When a generalized convulsive attack occurs, she shows rapid muscle twitches in her right arm and her consciousness is clear. She also has cerebellar ataxia in her extremities. Brain magnetic resonance imaging (MRI) showed obvious cerebellar atrophy, and an electroencephalogram revealed a diffuse spike and wave complexes. A surface electromyogram (EMG) confirmed myoclonus in both arms. We diagnosed her as having juvenile myoclonus epilepsy and initiated sodium valproate monotherapy, which relieved the symptoms. The observed cerebellar ataxia might be due to long-term administration of phenytoin. When a neurologist encounters an intractable seizure without loss of consciousness, surface EMG is useful for diagnosing this treatable disease.

[Late-onset leukoencephalopathy without hypertension in a case of young-adult-onset alopecia and spondylosis: a variant of CARASIL?].

We report herein a 61-year-old man with diffuse leukoencephalopathy, subcortical infarcts and cervical and lumbar spondylosis. Medical history included baldness and lumbar spondylosis at young-adult onset. His parents were consanguineous (cousin). He had been experiencing severe lumbago since 20-years-old, with hair loss starting around the same time. He noticed dysarthria and gait disturbance at 59-years-old. He was admitted to our hospital at 61-years-old with aggravation of gait disturbance. On admission, no abnormalities were evident on physical examination except for diffuse baldness. Neurological findings included mild dementia, bilateral hyperreflexia, paraparesis, right Babinski's sign, and pseudobulbar palsy. Blood pressure was normal. T2-weighted imaging of the brain revealed diffuse high-intensity in the periventricular white matter and subcortical infarcts in the brainstem and bilateral basal ganglia. Marked lumbar deformations were observed on spinal MRI. Clinical features in this case met the criteria for cerebral autosomal recessive arteriopathy with subcortical infarctions and leukoencephalopathy (CARASIL), apart from late onset of cerebral infarction.

[Pure amnesia due to the right capsular genu infarction].

A 77-year-old right-handed woman was admitted to our hospital with memory disturbance. Neurological examination was normal except for amnesia. Neuropsychological tests showed severe impairments in verbal and visual memories. Brain MRI revealed a fresh lacunar infarction in the genu of the right internal capsule. Decreased perfusion in the right thalamus and frontal lobe on (99m)Tc-ECD SPECT was attributable to disconnection of the thalamo-cortical tract by infarction. We consider that the patient's amnesia in this case was induced by infarction of the capsular genu, which includes some fibers from the anterior and inferior thalamic peduncles. Our findings demonstrated that lacunar infarction in the genu of the right internal capsule caused severe and persistent amnesia.