Elsberg syndrome: A rarely recognized cause of cauda equina syndrome and lower thoracic myelitis

Abstract

Objective: Elsberg syndrome (ES) is an established but often unrecognized cause of acute lumbosacral radiculitis with myelitis related to recent herpes virus infection. We defined ES, determined its frequency in patients with cauda equina syndrome (CES) with myelitis, and evaluated its clinical, radiologic, and microbiologic features and outcomes.

Methods: We searched the Mayo Clinic medical records for ES and subsequently for combinations of index terms to identify patients with suspected CES and myelitis.

Results: Our search yielded 30 patients, 2 diagnosed with ES and an additional 28 with clinical or radiologic evidence of CES retrospectively suspected of having ES. We classified patients in 5 groups according to diagnostic certainty. MRI and EMG confirmed that 2 had only myelitis, 5 only radiculitis, and 16 both. Two had preceding sacral herpes infection and 1 oral herpes simplex. Spinal cord lesions were commonly multiple, discontinuous, not expansile, and centrally or ventrally positioned. Lesions generally spared the distal conus. Nerve root enhancement was occasionally prominent and was smooth rather than nodular. Lymphocytic CSF pleocytosis was common. Thirteen patients (43%) had viral isolation studies, which were commonly delayed; the delay may have accounted for the low rate of viral detection. Acyclovir was administered to 6 patients. Most patients recovered with sequelae; 1 patient experienced encephalomyelitis and died.

Conclusion: ES is a definable condition likely responsible for 10% of patients with combined CES and myelitis. Radiologic findings are not entirely specific but may help in differentiating ES from some competing diagnostic considerations. We propose criteria to facilitate diagnosis.

Figure 1. Flow chart of patient selection

Interrogation of the electronic database for specific key terms highlighted in the first box returned a list of 1,035 patients. We excluded patients with an ICD code identifying NMO and MS, yielding 837 patients. Further interrogation of the database for patients with the following key terms returned 337 patients: “urinary retention” OR “paresthesia” OR “neuralgic pain” OR “constipation” OR “impotence” OR “perineal” OR “retention” OR “anus” OR “anal” OR “saddle”. After the review of individual clinical records of the remaining patients, we excluded 213 subjects who had likely or established alternative diagnoses, as listed in the figure, and only patients who were confirmed to have urinary retention and other sacral sensory symptoms were retained. Of the remaining 49 patients, 19 did not satisfy any of the levels of diagnostic certainty proposed in table 1. The remaining 30 were assigned a specific diagnostic category according to the level of suspicion for ES. ES = Elsberg syndrome; ICD = International Classification of Disease; NMO = neuromyelitis optica.

Figure 2. MRI evidence of myelitis and radiculitis in 6 patients

Patient A presents with concomitant presence of multiple and discontinuous T2 hyperintense lesions (A.a) that enhance on T1-weighted images after gadolinium injection (A.b) concomitantly with nerve roots of the cauda equina (A.b and A.c). Nerve root enhancement is prominent in 2 other patients (B.a, B.b, C.a, and C.b), with greater nerve root thickening in the latter (C.c). Two other patients had multifocal, discontinuous, T2-hyperintense lesions (D.a and E.a) as well as enhancement (D.b and E.b) in both the conus and lower thoracic cord. Finally, cord T2-hyperintense abnormality (F.a) may precede the onset of nerve root enhancement (F.b) by 26 days.