Case report: A patient with brachio-cervical inflammatory myopathy was misdiagnosed as flail arm syndrome.

Brachio-cervical inflammatory myopathy (BCIM) is a rare inflammatory myopathy characterized by dysphagia, bilateral upper limb atrophy, limb-girdle muscle weakness, and myositis-specific antibody (MSA) negativity. BCIM has a low incidence and is commonly associated with autoimmune diseases. We present a case report of a 55-year-old man with progressive upper limb weakness and atrophy, diagnosed with flail arm syndrome (FAS). The initial electromyography revealed extensive spontaneous muscle activity and increased duration of motor unit potentials (MUPs). During follow-up, evidence of myogenic damage was observed, as indicated by a decreased duration of MUPs in the right biceps muscle. Laboratory and genetic testing ruled out hereditary or acquired diseases. Negative serological antibodies for myasthenia gravis. Hereditary or acquired diseases were ruled out through laboratory and genetic testing. Whole-body muscle magnetic resonance imaging (MRI) showed extensive edema and fat replacement in the bilateral upper limbs, scapular, and central axis muscles, while the lower extremities were relatively mildly affected. Muscle biopsy revealed numerous foci of inflammatory cells distributed throughout the muscle bundle, with predominant CD20, CD138, and CD68 expression, accompanied by a light infiltration of CD3 and CD4 expression. The muscle weakness improved with the combination of oral prednisone (initially 60 mg/day, tapered) and methotrexate (5 mg/week) treatment.

Clinical and serological insights into paraneoplastic brachial amyotrophic diplegia.

BACKGROUND: Brachial amyotrophic diplegia (BAD) is typically linked to a neurodegenerative etiology such as amyotrophic lateral sclerosis (ALS). Clinical and serological characterizations of paraneoplastic neurologic syndromes resembling BAD are limited. METHODS: A retrospective chart review of patients with BAD-like presentations was conducted. Clinical/paraclinical features of paraneoplastic BAD and neurodegenerative BAD cases were compared. RESULTS: Between 2017 and 2023, 13 cases of BAD were identified, of these 10 were neurodegenerative BAD (ALS variant), and 3 cases associated with paraneoplastic autoimmunity. An additional paraneoplastic BAD case diagnosed in 2005 was included. LUZP4-IgG was detected in all four paraneoplastic cases, with coexisting KLHL11-IgG in three cases and ANNA1 (anti-Hu)-IgG in one case. Out of the four paraneoplastic cases, two patients had seminoma, while the remaining two had limited cancer investigation. Three patients exhibited bi-brachial weakness as the initial symptom before the onset of brainstem symptoms or seizures. Compared to BAD patients with a neurodegenerative etiology, a higher proportion of paraneoplastic cases had ataxia (75% vs 0%, p = 0.011). Other clinical features only detected in the paraneoplastic BAD group were vertigo (n = 2), hearing loss (n = 2) and ophthalmoplegia (n = 2). Electrodiagnostic studies in these patients revealed cervical myotome involvement, supportive of motor neuronopathy. All paraneoplastic cases but none of the neurodegenerative BAD cases exhibited inflammatory cerebrospinal fluid (CSF) findings (lymphocytic pleocytosis and/or supernumerary oligoclonal bands; p = 0.067). Despite the administration of immunotherapy and/or cancer treatment, none of the paraneoplastic patients reported clinical improvement. DISCUSSION: BAD or bi-brachial neurogenic weakness is a rare phenotypic presentation associated with paraneoplastic autoimmunity. Co-existing features of brainstem dysfunction or cerebellar ataxia should prompt further paraneoplastic evaluation. Common serological and cancer associations among these cases include LUZP4-IgG and KLHL11-IgG, along with testicular germ cell tumors, respectively.

The flail-arm syndrome: the influence of phenotypic features.

Objective: The flail-arm syndrome (FAS), one of the Amyotrophic lateral sclerosis (ALS) phenotypes, is characterized by slow progression and predominantly lower motor neuron (LMN) involvement with proximal upper limb (UL) weakness. We aim to characterize the clinical features, progression and survival of FAS associated with distal or proximal onset and presence or absence of upper motor neuron signs (UMN) signs at diagnosis. Methods: Data from 704 ALS patients was analyzed. Of the 190 patients with UL onset; 134 were excluded as not respecting the published criteria for FAS. The included patients were divided into four groups according to distal/proximal onset and presence/absence of UMN signs. Results: 56 FAS patients (8% of the population), median age at onset 59.9 years (Q1/Q3, 50.3-68.1), 75% men, were studied. Distal onset with UMN signs occurred in 37.5%, distal onset without UMN signs in 28.6%, proximal onset with UMN signs in 8.9% and proximal onset without UMN signs in 25%. Age of onset, sex, fasciculations at onset, diagnostic delay, progression rate, time to respiratory involvement and survival were similar among the four groups. Sex ratio was more balanced in patients with UMN signs (p = 0.032) and survival was shorter (69.5 months, 95% CI: 55.4-110.4 vs 152.6 months, 95% CI: 69.0-177.3; p = 0.035). The Cox regression identified rate of progression (p < 0.001) and UMN signs (p = 0.003) as independent predictors of shorter survival. Conclusions: Distal or proximal onset had no influence on clinical characteristics and prognosis but UMN signs at diagnosis are a negative prognostic predictor.

Radio Electric Asymmetric Conveyer (REAC) Neurobiological Stimulation Treatments in Dysfunctional Motor Behavior in Flail Arm Syndrome: A Case Report.

Flail arm syndrome (FAS) is a variant of amyotrophic lateral sclerosis (ALS) that manifests itself with the progressive loss of motor control of the upper limbs starting from the proximal part. Both electrophysiological and magnetic resonance studies have shown that functional alterations in the subcortical structures, cerebellum, and cortex are present in this pathology. These alterations appear to play a significant component in determining cognitive, motor, and behavioral effects. To try to modulate these alterations, in this case report, we used three noninvasive and specific neuromodulation treatments of the Radio Electric Asymmetric Conveyer (REAC) technology. The Neuro Postural Optimization (NPO), the Neuro Psycho Physical Optimization (NPPO), and the Neuro Psycho Physical Optimization Cervico-Brachial (NPPO-CB) with the aim of improving motor control, depression, anxiety, and stress. At the end of the treatment cycle that lasted five consecutive days, the patient regained the ability to raise his arms, a capacity he had lost for several months. This case demonstrates that REAC neurobiological modulation treatments aimed at improving dysfunctional neuropsychomotor behavior (DNPMB) can be useful in highlighting and reducing these components, allowing for better evaluation of the real neurodegenerative damage and determination of a better quality of life for these patients.

Involvement of cortico-efferent tracts in flail arm syndrome: a tract-of-interest-based DTI study.

BACKGROUND: Flail arm syndrome is a restricted phenotype of motor neuron disease that is characterized by progressive, predominantly proximal weakness and atrophy of the upper limbs. OBJECTIVE: The study was designed to investigate specific white matter alterations in diffusion tensor imaging (DTI) data from flail arm syndrome patients using a hypothesis-guided tract-of-interest-based approach to identify in vivo microstructural changes according to a neuropathologically defined amyotrophic lateral sclerosis (ALS)-related pathology of the cortico-efferent tracts. METHODS: DTI-based white matter mapping was performed both by an unbiased voxel-wise statistical comparison and by a hypothesis-guided tract-wise analysis of fractional anisotropy (FA) maps according to the neuropathological ALS-propagation pattern for 43 flail arm syndrome patients vs 43 'classical' ALS patients vs 40 matched controls. RESULTS: The analysis of white matter integrity demonstrated regional FA reductions for the flail arm syndrome group predominantly along the CST. In the tract-specific analysis according to the proposed sequential cerebral pathology pattern of ALS, the flail arm syndrome patients showed significant alterations of the specific tract systems that were identical to 'classical' ALS if compared to controls. CONCLUSIONS: The DTI study including the tract-of-interest-based analysis showed a microstructural involvement pattern in the brains of flail arm syndrome patients, supporting the hypothesis that flail arm syndrome is a phenotypical variant of ALS.

Upper Motor Neuron Signs in the Cervical Region of Patients With Flail Arm Syndrome.

Objective: We investigated upper motor neuron (UMN) signs in the cervical region in a Chinese clinic-based cohort of patients with flail arm syndrome (FAS) by clinical examination and neurophysiological tests such as triple stimulation technique (TST) and pectoralis tendon reflex testing. Methods: A total of 130 consecutive FAS patients from Peking University Third Hospital underwent physical examination and neurophysiological tests at baseline and 3 months, 6 months, 9 months, and 12 months later. Pyramidal signs, pectoralis tendon reflex and TST results were evaluated to estimate the function of cervical spinal UMNs. Results: At the first visit, weakness of the bilateral proximal upper limbs was found in 99 patients, while weakness of a single proximal upper limb was found in 31 patients. There were 49 patients with tendon hyperreflexia, 42 patients with tendon hyporeflexia and 39 patients with tendon areflexia. All except 4 of the patients had brisk pectoralis tendon reflex. The UMN score of the cervical region was 1.7 ± 0.4, and the lower motor neuron score of that region was 3.5 ± 0.3. The TSTtest/TSTcontrol amplitude ratio was 65.7 ± 7.5%. The latency of quantitative detection of the pectoralis tendon reflex was 7.7 ± 1.2 ms. In the follow-up study, the UMN score and the TSTtest/TSTcontrol amplitude ratio decreased, while the lower motor neuron score increased, and the latency of quantitative detection of the pectoralis tendon reflex remained steady. Conclusion: Although the signs of cervical spinal UMN dysfunction in patients with FAS were often concealed by muscle atrophy in the progression of the disease, TST and pectoralis tendon reflex could reveal it.

Twelve-month duration as an appropriate criterion for flail arm syndrome.

Objectives: To analyze the clinical features of flail arm syndrome (FAS) in a large Chinese clinic-based cohort, and to discuss whether it is proper to use a course of 12 months from symptoms onset as the criterion for FAS. Methods: This cohort study included patients with FAS or upper-limb-onset amyotrophic lateral sclerosis (UL-ALS) who visited Peking University Third Hospital between 2003 and 2013. Patients with FAS were diagnosed according to Wijesekera's definition, and patients fulfilling all the diagnostic criteria of FAS except that the course of disease was less than 12 months were defined as "FAS-type ALS". Group differences were analyzed using parametric and nonparametric tests as appropriate. Survival was analyzed using the Kaplan-Meier method and a Cox regression model. Results: One thousand nine hundred and thirty-five patients with ALS were recruited in the database, including 131 patients with FAS or FAS-type ALS and 767 with UL-ALS. The prognosis of FAS was significantly better than that of UL-ALS (p = 0.024) and FAS-type ALS (p < 0.0005), and the survival of patients with FAS-type ALS was worse than that of UL-ALS (p = 0.002). The difference in survival between those with proximal FAS (pFAS) and distal FAS (dFAS) (p = 0.188) was not significant. Conclusion: Since the prognosis of FAS-type ALS was significantly worse than that of FAS, our data suggest that a FAS subphenotype can be established after 12 months from first symptoms. It is important to note that FAS-type ALS phenotype may carry a worse prognosis than that of patients with UL-ALS.

Comparison between upper limb onset classic amyotrophic lateral sclerosis and flail-arm syndrome / 西安交通大学学报(医学版)

Objective: To investigate the clinical and electrophysiological characteristics of upper limb onset classic amyotrophic lateral sclerosis (ALS) and ALS variant flail-arm syndrome (FAS) so as to provide reference for differential diagnosis and prognosis. Methods: We recruited 120 upper limb onset classic ALS and 18 FAS patients from Neurology Department of The First Affiliated Hospital of Xi'an Jiaotong University between January 2013 and December 2018. The clinical and electrophysiological characteristics and survival were compared between the two groups. Results: Compared with those in upper limb onset classic ALS, FAS patients' diagnostic level was lower (P<0.001), diagnostic delay time was longer (15 mon vs. 11 mon; Z=-2.749, P=0.005), progression rate was slower (0.33 vs. 0.64; Z=-3.055, P=0.002), and time from the first region to the second was longer (33 mon vs. 8 mon; Z=-4.852, P<0.001). FAS patients were as likely to have single lateral upper limb onset as those with upper limb onset classic ALS, but the proportion of patients with bilateral upper limbs onset in FAS group was higher than that in the upper limb onset classic ALS group (33.3% vs. 8.3%; χ2=7.261, P=0.007), the proportion of proximal upper limb being more severely affected was higher in FAS group (55.6% vs. 18.3%; χ2=8.856, P=0.003). The proportion of FAS patients with high upper limb reflex or pathologic sign was lower (11.1% vs. 72.5%; χ2=25.759, P<0.001). Compared with upper limb onset classic ALS, FAS group's ratio of compound muscle action potential (CMAP)abductor pollicis brevis/CMAPabductor digiti minimi was higher, but without statistical significance; needle electrode electromyographic results were similar between the two groups. Survival time of FAS patients was longer than that of patients with upper limb onset classic ALS (53 mon vs. 22 mon; Z=-4.421, P<0.001), and FAS diagnosis itself was an independent prognostic factor of lower death risk compared with the diagnosis of upper limb onset classic ALS (HR=0.174, 95% CI: 0.061-0.496, P=0.001). Conclusion: Although natural histories of FAS and upper limb onset classic ALS are different, their EMG performance is similar. Characteristics including bilateral arms onset, proximal symptoms being severer than distal ones, lower motor neuron findings being more prominent have some implications for diagnosis of FAS.

Flail arm syndrome patients exhibit profound abnormalities in nerve conduction: an electromyography study.

Flail arm syndrome (FAS) is a rare degenerative disease of the nervous system and a variant of amyotrophic lateral sclerosis (ALS). In the current study, we sought to further delineate electromyographic changes in sensory and motor conduction of the median nerve in four FAS patients and also described one representative case of FAS in a 63-year old Chinese male patient who was admitted because of aggravating limb myasthenia for three months. Electromyography showed that FAS patients exhibited variable electromyographic changes in sensory conduction of the median nerve. Abnormal conduction velocity of the sensory nerve in bilateral median nerves was observed in one patient but normal in two other patients. Two patients had a marked reduction in median sensory nerve action potential amplitude. In addition, one patient showed significant reduction in the conduction velocity and motor nerve action potential amplitude. The latency of motor conduction of bilateral median nerves was markedly prolonged. Furthermore, the incidence rate of the F wave in the right median nerve ranged from 5% to 100%. Furthermore, all four patients exhibited abnormalities in needle electromyography in at least three regions of the four regions examined with massive denervations in large and widened motor units and diminished recruitment of motor units, indicating the simultaneous presence of both acute denervation and chronic nerve regeneration. In conclusion, this is the first detailed study of electromyographic changes in FAS and the findings help improve clinicians' understanding of this disease and differentiating the diagnoses of FAS from ALS.

Atypical Motor Neuron Disease variants: Still a diagnostic challenge in Neurology.

Motor neuron disease (MND) represents a wide and heterogeneous expanding group of disorders involving the upper or lower motor neurons, mainly represented by amyotrophic lateral sclerosis (ALS), primary lateral sclerosis, progressive muscular atrophy and progressive bulbar palsy. Primary motor neuronopathies are characterized by progressive degenerative loss of anterior horn cell motoneurons (lower motor neurons) or loss of giant pyramidal Betz cells (upper motor neurons). Despite its well-known natural history, pathophysiological and clinical characteristics for the most common MND, atypical clinical presentation and neurodegenerative mechanisms are commonly observed in rare clinical entities, so-called atypical variants of MND-ALS, including flail-leg syndrome, flail-arm syndrome, facial-onset sensory and motor neuronopathy (FOSMN), finger extension weakness and downbeat nystagmus (FEWDON-MND) and long-lasting and juvenile MND-ALS. Herein, we provide a review article presenting clinical, genetic, pathophysiological and neuroimaging findings of atypical variants of MND-ALS in clinical practice.

Electrophysiological characteristics of the split hand syndrome in amyotrophic lateral sclerosis and the variant / 中华神经科杂志

Objective To study the electrophysiological characteristics of hands muscle of upper limb onset amyotrophic lateral sclerosis (UL-ALS), and the variant-flail arm syndrome (FAS) for diagnosis and differential diagnosis. Methods We chose 55 UL-ALS and 12 FAS patients as the cases, 20 cervical spondylotic amyotrophy (CSA) patients as the case controls, and 20 healthy volunteers as the normal controls from January 2013 to March 2018 in the Third Central Hospital of Tianjin. Conventional nerve conduction studies of the median nerve and ulnar nerve were performed in all the patients. The main analysis was done in the compound muscle action potential (CMAP) recorded on the abductor pollicis brevis (APB) and abductor digiti minimi (ADM) and the ratio of the two. Results The ratio of CMAPAPB/CMAPADM of ALS was 0.59 (0.25, 0.79), which was depressed obviously compared with FAS (1.02 (0.92, 1.18), Z=-4.440, P=0.000), CSA (1.88 (1.42, 3.19), Z=-5.902,P=0.000) and the normal controls (0.96 (0.88, 1.15), Z=-5.416, P=0.000). The low ratio of CMAPAPB/CMAPADM (<0.6) was encountered in 40％(23/55) ALS patients, 0 CSA patient and 1/12 FAS patients. An absent APB CMAP and an abnormally low APB/ADM CMAP amplitude ratio (<0.25) were observed only in 25.4％ (14/55) ALS patients. The area under receiver operating characteristic curve in patients of UL-ALS was 0.911 (P=0.000), and in FAS was 0.518 (P=0.559). Using a cut-off value of CMAPAPB/CMAPADM=0.7 for diagnosing ALS yielded 85.5％sensitivity and 95.0％specificity. Conclusion The split hand syndrome is not specific for ALS; however, the low APB/ADM CMAP amplitude ratio may help predict prognosis and can be the diagnostic marker for ALS.

Chiari type I malformation with cervicothoracic syringomyelia subterfuge as flail arm syndrome.

Chiari type I malformation with cervicothoracic syringomyelia although very common in clinical practice usually in children can progress slowly and mimic muscular dystrophies in adulthood. We present a rare adult case of Chiari type I malformation with cervicothoracic syringomyelia subterfuge as Flail arm syndrome. A 44-year-old man was diagnosed with congenital type I Chiari malformation with cervicothoracic syringomyelia about 21 years ago without surgery. His health status deteriorated over the years until 21 days prior to presentation when he had severe pain in the right knee. In his upper limbs, he had bilateral corresponding severe weakness of 0/5 proximal strength and 0/5 strength in his distal muscles. Magnetic resonance imaging (MRI) revealed an enlargement of the spinal cord from C1-C4 level with a mass that appeared hypo-dense on T1 and hyperdense on T2. Syringomyelia is a potentially serious neurologic condition that can mimic other neuromuscular disorders. Early detection and diagnosis with MRI is crucial to avoid irreversible neurological complications. We suggest that whether asymptomatic or symptomatic, decompressive surgery should be carried out to allow for free flow of cerebrospinal fluid thereby improving the quality of life for the patient.

Absence of split hand in the flail arm variant of ALS.

Flail arm syndrome (FAS), a variant of amyotrophic lateral sclerosis (ALS), has many similarities with upper limb onset ALS (UL-ALS). This study analyzed the compound muscle action potentials (CMAPs) recorded from abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles in patients presenting these two types of ALS variants, compared to normal controls. The APB/ADM CMAP amplitude ratio was lower in the UL-ALS group (mean±SEM: 0.56±0.37), consistent with a split hand, compared to the FAS (1.05±0.29) or control (1.11±0.30) groups. An abnormally reduced APB/ADM CMAP amplitude ratio (<0.6) was found in 40% of UL-ALS patients and 11% of FAS patients. However, absent CMAP in the APB or extremely low APB/ADM CMAP amplitude ratio (<0.25) were observed only in UL-ALS patients (27%) and could be used as diagnostic criteria to differentiate UL-ALS from FAS variant.

Clinical features and differential diagnosis of flail arm syndrome.

Flail arm syndrome (FAS) is a variant of motor neuron disease which is characterized by progressive, predominantly proximal weakness and atrophy of the upper limbs (UL). Because of its heterogeneous presentation and its relatively slow progression, differential diagnosis may be difficult particularly in the early stages of the disease. The aim of this study was to investigate typical clinical features of FAS with special regard to initial symptoms and differences to classical Charcot type amyotrophic lateral sclerosis (ALS). We retrospectively evaluated the clinical features of 42 FAS patients who were seen in the outpatient clinics of 4 German centers between 2000 and 2010 and compared them to 146 sex-matched control patients with classical spinal-onset ALS. FAS patients were younger (54.7 ± 9.3 versus 59.4 ± 12.2 years), male patients were predominantly affected (3.8:1 versus 1.9:1), and FAS patients showed a prolonged survival (53 versus 33 months) compared to classical ALS patients. The share of patients with initial misdiagnoses was 54.8% and led to ineffective therapy with immunoglobulins in 26%. Initial symptoms were most frequently present either in distal muscles only or in both proximal and distal muscle groups combined (76%) and showed an asymmetric distribution pattern in the majority of cases (76%). Although all patients developed symmetric and predominantly proximal UL weakness and atrophy during the course of their disease, we found that most patients initially showed asymmetric and predominantly distal distribution of symptoms. This may contribute to difficulties in differential diagnosis and to ineffective treatment regimes.

Flail arm syndrome with cytoplasmic vacuoles in remaining anterior horn motor neurons: A peculiar variant of amyotrophic lateral sclerosis.

Flail arm (FA) syndrome, a minor subtype of amyotrophic lateral sclerosis (ALS), is characterized by progressive weakness and upper girdle wasting, but the associated pathological changes remain unclear. A 59-year-old man was admitted to our hospital with a 3-year history of upper girdle weakness. Bulbar symptom and gait disturbance gradually developed, and he was clinically diagnosed with FA syndrome. After a 10-year disease course, he died of pulmonary adenocarcinoma. Neuropathological examination revealed severe motor neuronal loss in the brain stem and anterior horn of the cervical spinal cord with bilateral pyramidal tract degeneration. The histological findings were consistent with typical ALS, including Bunina bodies and Lewy body-like and skein-like inclusions. Cytoplasmic vacuoles were found in the remaining anterior horn motor neurons of the lumbar spinal cord. This is a unique autopsy case with a long-standing clinical course that suggests that FA syndrome is an atypical form of ALS.

Ventilation function disorder of flail arm syndrome / 中华内科杂志

Objective To study the features of ventilation function in patients with flail arm syndrome (FAS).Methods The clinical data of 351 patients with sporadic amyotrophic lateral sclcrosis (ALS) fron 2009 to 2013 were retrospectively reviewed.Among them,329 were classical ALS and 22 were FAS.The differences of forced vital capacity (FVC) between FAS and classical ALS were analyzed.Results The percent predicted FVC (FVC％pred) values were (88.0 ±9.5)％ in FAS and (84.3 ± 16.8)％ in classical ALS including 4 and 128 patients with abnormal FVC％ pred (＜80％) in FAS and classical ALS,respectively.The FVC％ pred levels were significantly higher in FAS subjects [(88.0 ± 9.5) ％] than in classical ALS subjects of bulb [(80.0 ± 14.8) ％] or those of upper limb [(80.8 ± 16.0) ％] onset with duration over 12 months (All P ＜ 0.05).The proportion of subjects with FVC％pred ＜ 80％ was statistically lower in FAS [18.2％ (4/22)] than in both classical ALS of upper limb onset [42.8％ (80/187);P=0.037] and classical ALS with duration over one year [48.5％ (48/99);P =0.009].Conclusions Impaired ventilation function occurs less and later in FAS than that in classical ALS of upper limb onset with duration over one year,suggesting later and less requirement for non-invasive positive pressure ventilation treatment for FAS patients.Differentiation of FAS subjects from ALS helps assess prognosis and make treatment plan for these patients.

Surgical Treatment in Cervical Myelopathy Combined with Flail Arm Syndrome / 계명의대학술지

Flail arm syndrome (FAS) is a variant of the amyotrophic lateral sclerosis also known as Lou Gehrig's disease. FAS is a kind of motor neuron disease that represents a bilateral proximal muscle wasting of upper extremities. Degenerative cervical spondylosis is a common cause of cervical myelopathy and radiculopathy. The coexistence of cervical spondylosis and motor neuron disease can cause difficulties in diagnosis and treatment. This case is a cervical spondylotic myelopathy associated with FAS who had undergone surgical treatment. After the operation, subjective symptoms of the patient was more aggravated and it may be owing to natural history of FAS. The surgical treatment must be made very carefully in cervical spondylotic myelopathy patient combined with motor neuron disease.

Comparison between Flail Arm Syndrome and Upper Limb Onset Amyotrophic Lateral Sclerosis: Clinical Features and Electromyographic Findings.

Flail arm syndrome (FAS), an atypical presentation of amyotrophic lateral sclerosis (ALS), is characterized by progressive, predominantly proximal, weakness of upper limbs, without involvement of the lower limb, bulbar, or respiratory muscles. When encountering a patient who presents with this symptomatic profile, possible diagnoses include upper limb onset ALS (UL-ALS), and FAS. The lack of information regarding FAS may make differential diagnosis between FAS and UL-ALS difficult in clinical settings. The aim of this study was to compare clinical and electromyographic findings from patients diagnosed with FAS with those from patients diagnosed with UL-ALS. To accomplish this, 18 patients with FAS and 56 patients with UL-ALS were examined. Significant differences were observed between the 2 groups pertaining to the rate of fasciculation, patterns of predominantly affected muscles, and the Medical Research Council scale of the weakest muscle. The presence of upper motor neuron signs and lower motor neuron involvement evidenced through electromyography showed no significant between-group differences.

Comparison between Flail Arm Syndrome and Upper Limb Onset Amyotrophic Lateral Sclerosis: Clinical Features and Electromyographic Findings

Flail arm syndrome (FAS), an atypical presentation of amyotrophic lateral sclerosis (ALS), is characterized by progressive, predominantly proximal, weakness of upper limbs, without involvement of the lower limb, bulbar, or respiratory muscles. When encountering a patient who presents with this symptomatic profile, possible diagnoses include upper limb onset ALS (UL-ALS), and FAS. The lack of information regarding FAS may make differential diagnosis between FAS and UL-ALS difficult in clinical settings. The aim of this study was to compare clinical and electromyographic findings from patients diagnosed with FAS with those from patients diagnosed with UL-ALS. To accomplish this, 18 patients with FAS and 56 patients with UL-ALS were examined. Significant differences were observed between the 2 groups pertaining to the rate of fasciculation, patterns of predominantly affected muscles, and the Medical Research Council scale of the weakest muscle. The presence of upper motor neuron signs and lower motor neuron involvement evidenced through electromyography showed no significant between-group differences.