SynopsisPrimary lateral sclerosis (PLS) is characterized by insidious onset of progressive upper motor neuron dysfunction in the absence of clinical signs of lower motor neuron involvement. Patients experience stiffness, decreased balance and coordination, and mild weakness, and if the bulbar region is affected, difficulty speaking and swallowing, and emotional lability. The diagnosis is made based on clinical history, typical exam findings, and diagnostic testing negative for other causes of upper motor neuron dysfunction. EMG is normal, or only shows mild neurogenic findings in a few muscles, not meeting El Escorial criteria. Although no test is specific for PLS, some neurodiagnostic tests are supportive: including absent or delayed central motor conduction times; and changes in the precentral gyrus or corticospinal tracts on MRI, DTI or MR Spectroscopy. Treatment is largely supportive, and includes medications for spasticity, baclofen pump, and treatment for pseudobulbar affect. The prognosis in PLS is more benign than ALS, making this a useful diagnostic category.

A previously healthy 27-year-old woman developed a subacute myeloneuropathy after receiving nitrous oxide anesthesia for dental procedures. Neurologic evaluation revealed that she was vitamin B 12 deficient due to underlying pernicious anemia. Discontinuation of nitrous oxide and supplementation with vitamin B 12 resulted in dramatic clinical improvement, with near-complete normalization of her neurologic examination. This case and published reports reviewed here emphasize that favorable outcomes are possible following prompt recognition and treatment of vitamin B 12 deficiency.

Idiopathic neuropathy, now designated as chronic idiopathic axonal polyneuropathy (CIAP), is a major public health problem in the United States. The disorder affects an estimated 5-8 million Americans, comprising about one-third of patients with neuropathy, based on data from referral centers. Typically, patients develop symptoms in the sixth decade or older. The onset is insidious, with numbness, paresthesias, and pain appearing over months to years. Although strength is generally preserved, the sensory loss and pain can be disabling. The clinical approach to this condition has evolved in important ways over the years, enabling improved diagnosis and characterization of this population. Current work has focused on identifying modifiable risk factors that may be associated with idiopathic neuropathy. The results may suggest that an underlying mechanism such as oxidative stress contributes to the development of CIAP.

: Our experience supports the observation that PLS progresses more slowly than other forms of acquired motor neuron disease, particularly amyotrophic lateral sclerosis. Follow-up data suggest that patients with active denervation changes develop greater disability.

No abstract