Mark E. Baratz MD, and Katharine L. Baratz
Department of Orthopedic Surgery, Allegheny General Hospital, Pittsburgh, PA
A 48-year-old man was evaluated for left arm weakness. Nine months previously he awoke and realized that he was unable to lift his head off of his pillow. His neck weakness rapidly progressed to upper-trunk weakness and bilateral arm paralysis. Within 4 days he developed respiratory distress that was sufficiently severe to require mechanical ventilation for 3 months. Within 2 weeks after the onset of symptoms he experienced partial return of function in the right hand and elbow. After 9 months of extensive therapy he had recovered little function in either shoulder or in the left upper extremity.
Examination of both shoulders showed global atrophy, weakness, and limited elevation. The left biceps, brachialis, and triceps were graded at 2 out of 5 on the scale for muscle strength. The left hand had severe intrinsic atrophy including muscles innervated by both the ulnar and median nerves. The fingers rested in a clawed position with extension contractures of the second through fifth metacarpophalangeal joints. Sensation in the hand was normal. It is rare to see an individual with acute-onset nontraumatic hand and upper-limb atrophy. Possible diagnoses include spinal muscular atrophy, Charcot-Marie-Tooth disease, syringomyelia, poliomyelitis, Parsonage-Turner syndrome, and viral-induced neuritis.
Spinal muscular atrophy is characterized by symmetric limb weakness, primarily in newborns and infants. Neonates are prone to respiratory difficulty. The lower extremity is affected to a greater extent than the upper extremity. Sensation is unaffected. The condition is transmitted as an autosomal-recessive trait, most commonly in people of Middle Eastern descent. The weakness results from degeneration of the anterior horn cells.
Charcot-Marie-Tooth disease is one of a group of hereditary motor and sensory neuropathies affecting the peripheral nerves of young adults. The onset is gradual and is characterized by leg weakness with foot drop (peroneal muscular atrophy). Intrinsic atrophy of the hand appears later in the disease process.
Syringomyelia is a condition in which cerebrospinal fluid accumulates in the central canal of the spinal cord as a result of trauma to the cord or a congenital Arnold-Chiari malformation. Pooling of the cerebrospinal fluid creates a syrinx that compresses the spinal cord. Motor function mediated by the anterior horn cells and pain and temperature fibers in the posterior horn cells are affected to a greater extent than the large-fiber sensory neurons. Muscle wasting is most notable in the upper extremity.
Poliomyelitis results from poliovirus infecting and destroying cells within the brain stem and anterior horn cells of the spinal cord. The vast majority of patients infected with poliovirus have no symptoms and only 1% develop flaccid paralysis. Paralysis generally begins within several days of the flu-like prodrome. The paralysis progresses over 2 to 3 days and then improves. Permanent paralysis is uncommon in the upper extremity.
Parsonage-Turner syndrome (brachial neuritis) is characterized by diffuse unilateral upper-extremity pain and weakness. Motor and sensory changes typically do not follow a specific nerve distribution. The symptoms and weakness generally resolve within 6 months of onset.
This patient was diagnosed with West Nile virus (WNV), a condition most commonly transmitted to human beings through the bite of an infected mosquito. Although the vast majority of infected people present without symptoms, WNV symptoms generally are classified as flu-like and include febrile illness and neurologic symptoms including confusion, headaches, and weakness. WNV-induced weakness ranges from acute flaccid paralysis to disabling fatigue. There is no treatment for WNV beyond intensive supportive therapy to prevent secondary infections and rehabilitation to counteract the effects of weakness. Li et al 1 reported on 6 patients with WNV who presented with severe asymmetric or single-limb flaccid paralysis. In 3 of these patients there were minimal encephalitic or sensory signs and the physicians linked the cause of these conditions to an abnormality of either the spinal motor neurons or their ventral roots. Kraushaar et al 2 described a case of flaccid paralysis in the right arm. This patients paralysis was linked to an abnormality in the anterior horns of the cervical spinal cord, not unlike poliomyelitis. Saad et al 3 determined that the mortality rate for patients with acute flaccid paralysis linked to WNV was approximately 22%; a rate that is influenced by the age of the patient and the extent of the initial paralysis.
Three years after contracting WNV this patient has had no improvement in the function of either shoulder or in the left hand, forearm, or brachium.
The Journal of Hand Surgery. Volume 31, Issue 1 , January 2006, Pages 150-151.