Duration Of Symptoms Before Surgery Influences Outcome

Over the years, evidence has been building that the length of time a CM/SM patient has symptoms - symptom duration - negatively impacts their chance for a successful outcome. This makes sense intuitively, the longer the disease has to progress, the greater chance of permanent nerve or structural damage; however, not every study has supported this theory.

Now, doctors from France have published a study which seems to support the idea that symptoms duration is associated with surgical outcome. Dr. Nadine Attal, a neurologist at the Centre d'Evaluation et de Traitement de la Douleur, and her colleagues looked for predictors of improvement in sensory deficits and pain in 16 patients with syringomyelia. They published their results in the July issue of the Journal of Neurology, Neurosurgery, and Psychiatry.

Specifically, the study looked at thermal deficits (inability to feel temperature), mechanical and vibration sensory deficits, and levels of neuropathic pain, both before and after surgery. The subjects (see Figure 1) included 12 men and 4 women and included both Chiari related syringomyelia and post-traumatic syringomyelia patients. As a group, the patients had endured their symptoms for an average of 5 years.

Each subject was examined prior to surgery and 6 and 24 months after surgery. Sensory deficits were quantitatively determined using thermal stimuli, pin pricks, cottons swabs, and vibration filaments. Pain was recorded using a standard patient-reported number scale. In addition to the neurological exams, each patient underwent an MRI (at the same time periods). All the Chiari patients were treated with decompression surgery, and the area around the syrinx in the post-traumatic patients was surgically decompressed as well.

The researchers found that before surgery, every patient exhibited some level of thermal and mechanical sensory deficits. Interestingly, the deficits were similar in the Chiari patients and the post-traumatic patients. Deficits in sensing vibration were more common in the Chiari group. Eight of the patients reported suffering from neuropathic pain, which was described as a burning or squeezing sensation.

For the group as a whole, the surgery did not really improve the thermal deficits; however, a subgroup of patients did recover some or all of their temperature sensation. The doctors looked for several possible predictors of this improvement and found that in patients who had had symptoms for 2 years or less, their thermal deficits tended to improve. In contrast, in patients with symptoms duration of longer than 2 years, the thermal deficits only stabilized or even got worse.

Similarly, the researchers found that among the neuropathic pain group, the pain improved by 70% or more for the three patients who had had symptoms for less than 2 years. However, the number of patients in this group - three - is too small to draw any definitive conclusions from this result. It should also be noted that pain associated with exertion - Valsalva maneuver - was significantly improved for the group as a whole.

In an indication of the limited value of MRI's, the study found that while the syrinx collapsed completely in 12 people, there was no association between whether the syrinx shrank and whether sensory deficits or pain improved. This finding supports several research reports which have demonstrated there is no link between the general size of a syrinx and either symptoms or surgical outcome. There is some evidence, however, that the shape of a syrinx may be more important than it's size.

The authors of this study believe their work shows that Chiari related symptoms are less time sensitive than syringomyelia related symptoms. Either way, given that most published literature shows an average symptoms duration of 5+ years for patients, earlier diagnosis and treatment of CM/SM should improve outcomes and should remain an important goal for patients, advocates, and the medical community.

Figure 1
Selected Characteristics of Study Patients

Sex Age Symptom Duration (months) Syrinx Type Syrinx
M 44 120 C C2-T1
M 27 30 C C1-T12
M 31 18 C C2-T8
F 29 6 C C3-T8
M 27 18 C C1-T10
F 22 6 C C4-T12
F 46 132 C C7-T4
M 31 132 C C2-T6
F 43 30 C C2-T8
M 31 168 C C1-T12
M 39 72 C C1-T12
M 23 6 T C1-T7
M 44 60 T C1-T10
M 47 108 T C1-T12
M 55 48 T C1-L1
M 36 36 T T4-L1

Syrinx Type: C = Chiari, T=Trauma
Syrinx: C# = Cervical Vertebra; T# = Thoracic Vertebra #, L# = Lumbar Vertebra #