Treatment of Terminal Syringomyelia in Association with Tethered Cord Syndrome: Clinical Outcomes With and Without Syrinx Drainage

, , , , Department of Neurosurgery, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey

Neurosurg Focus. 2000;8(3) 

In This Article

Results

Characteristics such as age, causes of tethering, vertebral level of tethering were similar between the two treatment groups (Table 1). Despite the higher prevalence of paresis and congenital scoliosis in the group of patients who underwent an untethering-alone procedure (Group I) or of the bladder and bowel dysfunction in the patients who underwent untethering/drainage (Group II), the differences in presenting symptoms were not statistically significant. Likewise, the minimally observed differences in the mean duration of symptoms, the magnitude of the baseline neurological scores of motor function, sensory deficits, and bladder function, and the morphological characteristics of the syrinx cavities were insignificant (Table 1).

Clinical Outcome

Clinical outcomes in the 16 Group I patients (Table 2) and in the 14 Group II patients (Table 2) were evaluated at 1-year follow-up examination. In general, in patients in Group II better clinical outcomes were demonstrated than in those in Group I patients in whom untethering alone was performed (78% compared with 45%, respectively; p = 0.05); however, amelioration of motor, sensory, and urinary symptoms differed.

Motor Outcome. Of the nine patients with paresis in Group II, seven (78%) improved, one (11%) worsened, and one (11%) was unchanged, whereas of the 14 patients in Group I with paresis, improvement was attained in seven (50%), deterioration continued in one (7%), and no change was observed in six patients (43%).

Sensory Outcome. Of the 12 patients with sensory deficits in Group II, 11 (92%) improved, and one (8%) was unchanged, whereas of the 14 patients in Group I, improvement was observed in seven (50%) and no change or worsened in seven (50%).

Urinary Outcome. Of the 11 patients with incontinence in Group II, eight (70%) improved and three (27%) were unchanged, whereas of the 10 patients with incontinence in Group I, improvement was seen in three (30%) and no change was observed in seven (70%).

The differences in the improvement rates of sensory deficits and urinary dysfunction between two treatment groups were statistically significant (p = 0.036 and p = 0.05, respectively) and were large enough to be of clinical importance (95% CI 10-70 and 95% CI 12-68, respectively), in favor of the patients in Group II who underwent the combined procedure. Results of motor improvement did not reach statistical significance when the two groups were compared (p = 0.228, 95% CI -9 to 66).

Radiological Outcome

Control MR images obtained 1 year postoperatively demonstrated a reduction in syrinx size in 15 cases (50%), no change in 14 cases (47%), and enlargement in one case (3%). To evaluate the correlation between radiological and neurological outcomes, clinical responses in motor, sensory, and urinary symptoms were compared between the syrinx size-reduced and syrinx size-unchanged cases. Compared with the improvement in six of 12 cases with unchanged syrinx size, resolution of the sensory deficits was observed in 12 of 14 in whom syrinx size was reduced (p = 0.046, 95% CI 2-68). Likewise, improvement in bladder dysfunction seen in three of nine patients in whom syrinx size was unchanged, was observed in 10 of 12 patients in whom syrinx size was reduced (p = 0.019, 95% CI 10-90). However, the motor improvement rate between patients in whom the syrinx size was unchanged (five of 11) and those in whom it was reduced (nine of 12) was not significant (p = 0.214, 95% CI -5 to 69).

Subgroup Analysis

Because the response to surgery varies in each form of spinal dysraphism as a consequence of the morbid anatomy of the myelodysplastic spinal cord, clinical outcomes in syrinx-unchanged and syrinx-reduced cases were compared within the homogenous tethering subgroups. In thick filum terminale cases, improvement was attained in five of the five cases with reduced syrinx size, as compared with two of the seven cases with unchanged syrinx size (p = 0.028). Of interest, four of the five cases with unchanged clinical outcome, had distended syrinx cavities with syrinx index of more than or equal to 50%. In patients with diastematomyelia in whom the syrinx was reduced in size, a 100% improvement rate was demonstrated (six of six), whereas this rate was 50% (four of eight) in those with unchanged syrinx size (p = 0.085). In previously operated lipomyelomeningocele cases, only one of the four patients with reduced syrinx size improved, and no improvement was noted in the patient with unchanged syrinx size (p = 1.00).

There was no surgery-related mortality; however, additional neurological deficits were observed after myelotomy procedures in which small syringes (syrinx index < 40%) were treated: two patients experienced transient dysesthesia (in a dermatome corresponding to the location of their myelotomy); one patient defined saddle numbness; and in one patient bladder distention occurred. The latter patient regained bladder control within 6 weeks, and dysesthesia resolved in former cases by 4 to 6 months.

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