Elsevier

Surgical Neurology

Volume 69, Issue 3, March 2008, Pages 266-273
Surgical Neurology

Technique
Dorsal root ganglionectomy for the diagnosis of sensory neuropathies. Surgical technique and results

https://doi.org/10.1016/j.surneu.2007.01.057Get rights and content

Abstract

Background

Inflammatory diseases stand out among sensory neuronopathies because, in their active phase, they can be treated with immunosuppressive agents. Immunosuppressive therapy may present severe adverse effects and requires previous inflammatory activity confirmation. Sensory neuronopathies are diagnosed based on clinical and EMG findings. Diagnostic confirmation and identification of inflammatory activity are based on sensory ganglion histopathological examination. We describe the surgical technique used for dorsal root ganglionectomy in patients with clinical/EMG diagnosis of sensory neuronopathies.

Methods

The sensory ganglion was obtained from 15 patients through a small T7-T8 hemilaminectomy and foraminotomy to expose the C7 root from its origin to the spinal nerve bifurcation. In 6 patients, the dural cuff supposed to contain the ganglion was resected en bloc; and in 9 patients, the ganglion was obtained through a longitudinal incision of the dural cuff and microsurgical dissection from the ventral and dorsal roots and radicular arteries. All ganglia were histopathologically examined.

Results

No ganglion was found in the dural cuff in 2 patients submitted to en bloc removal, and the ganglion was removed in all patients who underwent microsurgical dissection. All but 2 patients that had ganglion examination presented a neuronopathy of nerve cell loss, 3 with mononuclear inflammatory infiltrate. These patients underwent immunosuppressive therapy, and 2 of them presented clinical improvement. No surgical complications were observed.

Conclusions

Microsurgical dorsal root ganglionectomy for diagnosing inflammatory sensory ganglionopathies was effective and safe. Although safe, en bloc resection of the proximal dural cuff was not effective for this purpose.

Introduction

Sensory neuropathies associated or not with an autonomic and with a small or absent motor component may be predominantly secondary to involvement of dorsal root ganglia. Subacute or chronic “polyganglioneuronopathies” [23] occurring in patients not using medications or not exposed to industrial toxic agents may be associated with carcinomas, [5], [25] with Sjögren syndrome, [1], [8], [9], [10], [12], [13], [14], [16], [17] or with monoclonal gammopathies, [4] or may be idiopathic. Idiopathic NISPs [23] are ganglionopathies of unknown nature, although there are suggestions that they may depend on an underlying autoimmune process. Information about the pathology of NISP is limited because few reports are available about autopsies or biopsies of the dorsal root ganglion. These findings include a mononuclear inflammatory infiltrate consisting of T cells of the cytotoxic/suppressor type, [9] deposits of immunoglobulin, [4] and reduced number of neurons with proliferation of satellite cells. No effective treatment exists for NISP, but a clinical improvement occurred in a patient with the use of prednisone. Clinical improvement has been reported for another patient treated with plasmapheresis. [1] There are also reports of spontaneous improvements that, paradoxically, are related to electrophysiological worsening. This fact may depend on functional improvement by adaptation of the patient to his sensory ataxia. [9] However, no controlled studies are available in which the efficacy of any treatment was confirmed. Because there are no estimates of its incidence or prevalence among nonhospital populations and because idiopathic NISP seems not to be frequent, a controlled study of this type should be multicentric.

In view of the above considerations and of the fact that sensory ataxia as well as pain may be incapacitating in patients with NISP, the neurologist, based on the pertinent medical literature and with the patient agreement, is ethically authorized to make attempts to treat with plasmapheresis, corticosteroids, and nonsteroidal immunosuppressive drugs. The doses used, the duration of the therapeutic attempt, and the combination of different types of immunosuppressive treatments mainly depend on the presence of an inflammatory process. This is determined by the detection of an inflammatory infiltrate and/or deposits of immunoglobulins in the sensory ganglia. This detection is possible only by a ganglionectomy, which, however, is an invasive procedure requiring general anesthesia. The procedure should be carried out only after the patient has been fully informed about all surgical steps and risks and only if he is willing to submit to immunosuppressive treatment. Few reports of sensory ganglion exeresis are available. Smith [22] and Osgood et al [19] have described techniques for sensory ganglion exeresis in the thoracic and lumbosacral region, respectively, for the treatment of chronic pain. Griffin et al [9] reported exeresis of a sensory ganglion in the thoracic region for histopathological examination but did not describe in detail the technique used.

The objective of this study was to describe the surgical technique used for exeresis of a dorsal root ganglion in patients with NISP diagnosed based on clinical and EMG criteria [23].

Section snippets

Materials and methods

This study was approved by the Ethical Committee of the Hospital das Clínicas, Ribeirão Preto Medical School, University of São Paulo.

Results

Table 1 presents a summary of the clinical, EMG, and histopathological findings and the surgical technique used in 15 patients submitted to ganglionectomy. No ganglion was included in the removed segment in 2 of 6 patients submitted to en bloc removal of the dural cuff. In all patients submitted to dural cuff opening, the ganglion could be well identified and removed with the dorsal root or en bloc with the ventral and dorsal roots. No surgical complications or postoperative neurological

Clinicopathological comments

Although it was not the aim of this study to analyze the clinicopathological aspects, they deserve comments. No cellular infiltrates or deposits of immunoglobulins were found in the ganglia of our patients. This may be due to the chronicity of our cases (phase without active inflammation), even considering that the disease seemed to be insidious and slowly progressive. Recently, some studies suggested that these ganglionopathies might be associated with antiglycolipid antibodies. [9], [15], [19]

Conclusions

Ganglionectomy of dorsal root ganglion using microsurgical techniques for diagnosis of the NISPs was effective and safe. Although safe, en bloc resection of the proximal dural cuff was not an effective technique for this purpose.

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