Sensory Polyradiculopathy

Abstract and Commentary

Synopsis: This condition preferentially affects large myelinated fibers of the posterior roots, may respond favorably to treatment, and may be a restricted form of chronic inflammatory demyelinating polyradiculoneuropathy.

Source: Sinnreich M, et al. Chronic Immune Sensory Polyradiculopathy: A Possibly Treatable Sensory Ataxia. Neurology. 2004;63;1662-1669.

Retrospective chart review from 1990-2002 at the Mayo Clinic revealed 15 patients with sensory ataxia due to inflammatory demyelination at the dorsal root level. Criteria for including patients in the analysis comprised a sensory syndrome in the absence of muscle weakness, normal peripheral nerve conduction study and electromyography with abnormal somatosensory evoked potentials, and neuroimaging studies of the neuraxis that excluded a compressive lesion, but were consistent with nerve root inflammation. Nerve rootlet biopsy data was available in 3 patients. All had normal or negative B12 levels, syphilis serology, thyroid function, ACE level, and ANA and ENA antibodies. Paraneoplastic antibody screen was negative in all 12 patients tested.

Among the 15 patients, 10 men and 5 women with a median age of onset of 63 years, all experienced gait ataxia, causing frequent falls in 9; 3 required wheelchair assistance. Arm ataxia was present in 7. Leg paresthesiae and dead-like numbness was experienced in all patients, with arm paresthesiae and numbness in 12 and 4, respectively. Onset was unilateral or asymmetric in 7, progressed in all with no instance of spontaneous improvement, and eventually became symmetric in 12. Examination revealed impaired position and vibration sensation in all, with absent deep tendon reflexes in 14 and impaired small fiber sensation in 10. None had weakness (by choice of inclusion criteria). Cerebrospinal fluid protein elevation was documented in 13 of 14 patients tested; values ranged from 31 to 161 mg/dL, with a median of 83 mg/dL. None demonstrated white cells or oligoclonal bands. Enlarged lumbar nerve roots were seen on MRI in 5; 3 showed enhancement with GAD. Sural nerve biopsy was normal in 2. Nerve rootlet biopsy in 3 showed decreased numbers of large myelinated fibers, with onion bulb formation and demyelinated axons in 2. Intravenous immunoglobulin alone (n = 4) or combined with intravenous steroids (n = 2) administered to the 6 most severely affected patients, resulted in striking improvement in all; 4 returned to independent ambulation. Chronic inflammatory sensory polyradiculopathy (CISP) appears to be an autoimmune mediated syndrome affecting the dorsal roots proximal to the dorsal root ganglia, and is responsive to immune modulating therapy. It is eminently treatable, and should not be overlooked.

Commentary

Chronic inflammatory sensory polyradiculopathy may have a motor equivalent. One month following a low grade fever and upper respiratory tract infection, and 12 days following maintenance chemotherapy including intrathecal methotrexate, Ara-C, and hydrocortisone, with intravenous vincristine, for acute lymphocytic leukemia (ALL) in remission, bilateral leg weakness, and areflexia developed in a 3-year-old girl (Muscle Nerve. 2002;25;106-110). Sensation was normal, as were blood studies including complete blood count, erythrocyte sedimentation rate, creatine kinase, thyroid-stimulating hormone, and blood cultures. Cerebrospinal fluid analysis showed no malignant cells or white cells, but elevated protein (107mg/dL). Lumbar MRI with GAD revealed enhancement of multiple ventral nerve roots of the cauda equina. Initial electrodiagnostic studies revealed normal sensory nerve conduction studies, low motor evoked amplitudes, absence of motor conduction block, and no spontaneous activity on needle electromyography. Empirical treatment with intravenous immunoglobulin resulted in improvement within 3 days, and independent ambulation with return of reflexes by 4 weeks. CSF remained free of malignant cells, and later needle EMG showed denervation and reinnervation. This patient’s clinical presentation, electrodiagnostic studies, CSF protein, MRI, and response to intravenous immunoglobulin are consistent with an autoimmune process affecting the ventral roots triggered by her antecedent URI or chemotherapy or both, and may be the motor equivalent of chronic inflammatory sensory polyradiculopathy. — Michael Rubin

Dr. Rubin, Professor of Clinical Neurology, New York Presbyterian Hospital-Cornell Campus, is Assistant Editor of Neurology Alert.