Research analyzes if decompression surgery provides pain relief to patients with two difficult to treat conditions: Chiari type 1 malformation and syringomyelia
Source: American Association of Neurological Surgeons
Author: Betsy van Die
Date: 29 April 2008
Chiari malformation is considered a congenital condition, although acquired forms of the condition have been diagnosed. A German pathologist, Professor Hans Chiari, first described abnormalities of the brain at the junction of the skull with the spine in the 1890s. He categorized these in order of severity; types I, II, III, and IV. These malformations are closely related to syringomyelia. Patients with syringomyelia and Chiari Type 1 often present with an intense, burning-type nerve pain and/or headaches, among other symptoms. The prevalence in the general population has been estimated at slightly less than one in 1000.
When cerebrospinal fluid (CSF) forms a cavity or cyst within the spinal cord, it is known as syringomyelia. This is a chronic disorder involving the spinal cord developing, expanding or extending over time. As the fluid cavity expands, it can displace or injure the nerve fibers inside the spinal cord. A wide variety of symptoms can occur, depending upon the size and location of the syrinx. Loss of sensation and pain are two of the symptoms. Syringomyelia can arise from several causes. While Chiari malformation is the leading cause, the direct link is not well understood.
Surgical treatment of Chiari depends on the type of malformation. The goal of surgery is to relieve or stop the progression of the syrinx and/or symptoms by decompressing nerve tissue and restoring normal CSF flow around and behind the cerebellum. Decompression provides more space for the brain stem, spinal cord, and descended cerebellar components. "This is a particularly challenging condition to diagnose and treat for several reasons. Many of the symptoms mimic other conditions such as fibromyalgia, and patients often go for years before receiving a proper diagnosis. While decompression surgery has proven to help some patients, there have been other cases in which the symptoms persisted, which warrants the need for in-depth outcome research," stated Kazutoshi Hida, MD, PhD, lead author of this study.
Researchers at the University of Hokkaido in Sapporo, Japan , analyzed the outcome of 66 patients with Chiari Type 1 or syringomyelia presenting with pain as one of their symptoms. The results of this study, Dysesthetic Pain in Patients with Syringomyelia and Chiari Type I Malformation, will be presented by Dr. Hida at 4:09 to 4:20 p.m. on Wednesday, April 30, 2008, during the 76th Annual Meeting of the American Association of Neurological Surgeons in Chicago. Co-authors are Yoshinobu Iwasaki, MD, PhD, and Shunsuke Yano, MD, PhD.
Since 1982, 148 patients with syringomyelia and Chiari Type I malformation have undergone surgery at the University of Hokkaido. Of these, 66 (17 men and 49 women) complained of pain preoperatively, and these patients were included in this study.
- Foramen magnum decompression (FMD) was performed on 36 patients and syringo-subarachnoid (S-S) shunting on 30 patients.
- Pain was more common in adult patients than in younger patients.
- Pain in one arm was the most frequently observed pattern in 79 per cent of patients.
- In 52 patients (78 per cent), preoperative magnetic resonance imaging (MRI) showed extension of the syrinx into the dorsolateral part of the spinal cord on the same side and level as the pain.
Postoperatively, MRI showed a reduction of the size of the syrinx in all 66 patients. Forty-six reported pain relief or improvement; 17 reported no change, and three experienced worsening of pain. In respect to pain outcome, there was no difference between patients treated with FMD and S-S shunting. "While surgery is effective in reducing the size of the syrinx, this reduction does not seem to correlate to pain relief. However, early syrinx reduction may minimize the long-term pain experienced by patients with syringomyelia."
"It is really key that patients with either of these conditions work closely with their neurosurgeons and other healthcare providers on pain management strategies, because while surgery may help, it does not always provide complete resolution of symptoms," concluded Dr. Hida.