A Strong Diagnosis of Weakness

A 52-year-old man presented with bilateral weakness in all extremities. He noted the gradual onset of progressive muscle weakness 6 months prior to presentation. He reported generalized fatigue and difficulty with climbing stairs and carrying heavy objects.

Initial considerations of chronic weakness and fatigue are myopathy, polyneuropathy, medications, malignancy, endocrinopathies, human immunodeficiency virus (HIV), neuromuscular junction dysfunction, and central nervous system (CNS) disorders, such as amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS). Symmetrical muscle involvement and proximal weakness make myopathy most likely. Polyneuropathy, such as chronic inflammatory demyelinating polyneuropathy (CIDP), is less likely but still possible given the slowly progressive course. The use of medications that can cause myopathy should be explored, including colchicine, steroids, and statins. Gathering further history should focus on risk factors for HIV, as well as alcohol and illicit drug use. Malignancy can cause paraneoplastic myopathy. The review of systems should include symptoms of endocrinopathies, such as thyrotoxicosis and hypothyroidism. Fluctuations in weakness and dysphagia or ocular symptoms would suggest myasthenia gravis (MG). The time course and symmetrical weakness make a central disorder, such as ALS or MS, unlikely.

His past medical history was notable for pulmonary tuberculosis diagnosed at the age of 6 years, which was treated with hospitalization and an unknown medication regimen. He was not taking medications prior to this admission. His family history was significant for diabetes mellitus in both parents. He denied sick contacts. He was sexually active with his wife. He denied the use of tobacco and illicit drugs but endorsed alcohol consumption on a daily basis over the last 32 years. He reported no fluctuation in his symptoms, muscle or joint pains, rash, fevers, chills, diaphoresis, chest pain, dyspnea, abdominal pain, diarrhea, paresthesias, weight loss, or night sweats. He had never had a colonoscopy.

Painless progressive weakness of the limbs without sensory deficit is typical of a myopathy. Though CIDP can present with only motor weakness, the majority of patients have sensory symptoms, making this less likely. Although chronic alcohol abuse can cause myopathy, it seems less likely because other neurologic complications, such as sensory polyneuropathy or ataxia, would be expected. A review of systems does not suggest a thyroid disorder or malignancy, although this does not preclude an evaluation for both. The absence of fluctuations in weakness argues against MG. Though ALS, MG, MS, and CIDP are less likely, a neurologic exam is crucial in excluding them. The hallmark of ALS is upper motor neuron (UMN) and lower motor neuron signs in the absence of sensory symptoms and signs, while global hyporeflexia would be expected in CIDP, and fatigability on repeated power testing would be expected in MG. Neurologic findings disseminated in space (neuro-anatomically) would be expected in MS.

On physical examination, the patient had a temperature of 36.9°C, heart rate of 70 beats per minute, and regular respiratory rate of 10 breaths per minute, blood pressure 130/80 mmHg, and oxygen saturation 98% while breathing ambient air. Auscultation of the heart and lungs revealed normal findings. The abdomen was soft, nontender, and without masses or organomegaly. Neurologic examination disclosed bilateral symmetric upper and lower extremity weakness with positive Gower sign. Muscle strength scores of the bilateral biceps brachii, iliopsoas, and digitis extensor were between 4 and 5 without fatigability. Grasping power was impaired. Deep tendon reflexes were preserved, and there were no UMN signs. There was no tenderness to palpation in any muscle groups. Sensory testing was normal. Skin and lymph examinations were without abnormality. The rest of the physical examination was unremarkable.

Gower sign, characteristic of but not specific to muscular dystrophy, indicates proximal muscle weakness of lower extremities, wherein hands and arms are used to walk up the body into an upright position. The exam also reveals distal weakness as shown by reduced hand grasp. Symmetrical proximal weakness of all extremities without sensory deficits suggests a myopathic process, albeit one with some distal involvement. The absence of UMN signs argues against ALS, lack of fatigability argues against MG, and the absence of CNS or sensory deficits argues against MS.