200 Section - Electromyography clarifies diagnosis and treatment in case of Lyme meningoradiculitis

Case Diagnosis: Lyme meningoradiculitis diagnosis aided by electromyography and nerve conduction results.

Case Description: A sixty-six-year-old man was admitted to the hospital for worsening low back pain with sudden left foot drop and ascending paresthesia. The patient had recent cellulitis left lower leg. Outpatient magnetic resonance imaging of the lumbar spine showed enhancement along the cauda equina nerve roots without clumping. Physiatry was consulted to evaluate due to concern for acute inflammatory demyelinating polyneuropathy (AIDP). 
The physical exam revealed reduced sensitivity to light touch distal to the ankles bilaterally. There was left-sided weakness in ankle dorsiflexion and hallux extension. Reflexes were absent in the achilles on the left. 
EMG findings were consistent with acute bilateral lumbosacral polyradiculopathy primarily affecting the L5/S1 nerve roots, with greater involvement on the left compared to the right, with active muscle membrane irritability and denervation. EMG findings were not consistent with lumbosacral plexopathy, large fiber peripheral polyneuropathy, type 1 fiber myopathy, or primarily demyelinating processes such as AIDP. 

Discussions: Lyme meningoradiculitis, also known as Bannworth syndrome, is present in three percent of lyme cases reported in the United States. Lyme disease, caused by Borrelia bacteria transmitted through tick bite, is most prevalent in the coastal northeastern United States, but can be seen outside endemic areas. Direct hematogenous spread is an explanation for the dissemination of lyme disease, but cases of lyme meningoradiculitis are consistent with spread through peripheral nerves. Treating physicians did not initially suspect Lyme meningoradiculitis, likely due to it not being endemic to the area. 

Conclusions: Lyme diagnosis was confirmed by serology. Treatment was initiated with intravenous ceftriaxone. Exclusion of AIDP by EMG had a direct impact on treatment choice. After starting treatment, the patient had improvement of his symptoms before hospital discharge.