Kestenbaum and artificial divergence surgery for abnormal head turn secondary to nystagmus. Specific and nonspecific effects of artificial divergence

Design and efficacy of surgery for horizontal idiopathic nystagmus with abnormal head posture and strabismus

The design and efficacy of surgery for horizontal idiopathic nystagmus (HIN) with abnormal head posture and strabismus were investigated. Different surgical procedures were selected according to the angle of head turn in 44 cases of HIN with abnormal head posture and strabismus. For patients with a head turn of 15° or less, the Anderson procedure was used; the yoke muscles were recessed upon slow-phase. For patients with a head turn between 15° and 25°, the surgery was designed as a Kestenbaum 5-4-4-5 procedure. For patients with a head turn of 25° or more, the surgery was designed as a Parks 5-8-6-7 procedure. The surgery to correct the abnormal head posture was performed on the fixating eye while that to correct the deviation was then performed on the non-fixating eye at the same time. The amount of surgery of the horizontal rectus muscles on the non-fixating eye was sum of the angle of head turn and the degree of deviation, which was calculated as follows: recession/resection amount of medial and lateral rectis / 2×5 =angle of head turn ± degree of deviation. The results showed as follows: (1) Visual acuity: the visual acuity in the primary ocular position increased two lines or more in 35 patients, accounting for 79.55%. Nine patients had no or only one-line improvement, accounting for 20.45% of the entire study population; (2) The degree of deviation in the primary ocular position: 37 cases had a normal primary ocular position or the degree of deviation ≤ 8(δ) after surgery, accounting for 84.09%. Six patients had a residual degree of deviation of 8(δ)-15(δ), accounting for 13.64%. One patient had a residual degree of deviation >20(δ), accounting for 2.27% of the patients examined; (3) Abnormal head posture: 34 patients had a normal head posture or a head turn of less than 5°, accounting for 72.27%. Eight patients had a residual head turn of 5°-15°, accounting for 18.18%. Two patients had a head turn of 15°-25°, accounting for 4.55%. It was concluded that different surgical procedures based on the angle of head turn and the relationship between deviation and null zone can eliminate anomalous head posture, correct deviation, and improve vision acuity in the primary ocular position.

Surgery for the treatment of vertical head posturing associated with infantile nystagmus syndrome: results in 24 patients

BACKGROUND

The study of the clinical and electrophysiological effects of eye muscle surgery on patients with infantile nystagmus has broadened our knowledge of the disease and its interventions.

DESIGN

Prospective, comparative, interventional case series.

PARTICIPANTS

Twenty-four patients with a vertical head posture because of electrophysiologically diagnosed infantile nystagmus syndrome. The ages ranged from 2.5 to 38 years and follow up averaged 14.0 months.

METHODS

Thirteen patients with a chin-down posture had a bilateral superior rectus recession, inferior oblique myectomy and a horizontal rectus recession or tenotomy. Those 11 with a chin-up posture had a bilateral superior oblique tenectomy, inferior rectus recession and a horizontal rectus recession or tenotomy.

MAIN OUTCOME MEASURES

Outcome measures included: demography, eye/systemic conditions and preoperative and postoperative; binocular, best optically corrected, null zone acuity, head posture, null zone foveation time and nystagmus waveform changes.

RESULTS

Associated conditions were strabismus in 66%, ametropia in 96%, amblyopia in 46% and optic nerve, foveal dysplasia or albinism in 54%. Null zone acuity increased at least 0.1 logMAR in 20 patients (P < 0.05 group mean change). Patients had significant (P < 0.05) improvements in degrees of head posture, average foveation time in milliseconds and infantile nystagmus syndrome waveform improvements.

CONCLUSIONS

This study illustrates a successful surgical approach to treatment and provides expectations of ocular motor and visual results after vertical head posture surgery because of an eccentric gaze null in patients with infantile nystagmus syndrome.

Kestenbaum procedure with posterior fixation suture for anomalous head posture in infantile nystagmus

BACKGROUND

The purpose of this study was to report the effect of combining the Kestenbaum procedure with posterior fixation suture for infantile horizontal nystagmus with anomalous head posture (AHP) in children.

METHODS

Nine consecutive patients who underwent combined Kestenbaum procedure plus posterior fixation suture to the recessed muscles at the same time were retrospectively studied. All patients were orthotropic before surgery and were followed for at least 6 months. Pre- and postoperative AHP and binocular corrected visual acuity (BCVA), and ocular alignment were assessed.

RESULTS

Mean age at surgery was 4.8 +/- 1.5 years. The average follow-up was 29.7 months. The average head turn preoperatively was 27.4 degrees and postoperatively 7.2 degrees . The average net change in AHP was 24.8 degrees (P = 0.008). Seven of 9 patients (78%) achieved a residual head turn of 10 degrees or less. The average Log Mar BCVA was 0.33 preoperatively and 0.31 postoperatively (P = 0.68). Only 1 patient needed additional surgery for residual horizontal AHP. No patient developed strabismus.

CONCLUSION

Combined Kestenbaum procedure with posterior fixation suture was an effective and stable procedure in reducing AHP of the range of 20 degrees to 35 degrees in children with infantile nystagmus.

Interventions for infantile nystagmus syndrome: towards a randomized controlled trial?

A PubMed search for papers in the last 10 years on interventions for Infantile Nystagmus Syndrome (INS) reveals 18 papers on surgical or pharmacological interventions and 6 papers describing other interventions. There is only one randomized controlled trial (RCT), with all the other studies being uncontrolled trials/case series. To investigate the importance of RCTs, the data from the one RCT is re-analyzed as if it had been a case series. If only the group receiving the experimental treatment are considered, then the visual acuity was significantly better after than before treatment (paired t-test, p = 0.04). However, the control group who received a placebo treatment improved to a similar degree (p = 0.90). The literature on the placebo effect shows that it can influence objective variables and the outcome of surgical interventions. It is suggested that previous studies on interventions for nystagmus have laid an important foundation for future work in this field, which should involve RCTs.

Current treatment of nystagmus

Acquired and congenital nystagmus often causes decreased visual acuity as a direct result of the inability to maintain stable foveal vision. In addition, acquired nystagmus causes a disabling subjective sensation of movement of the visual world called oscillopsia. The eye movements themselves do not require treatment if the patient is asymptomatic. However, therapy is necessary if visual disability is present. Treatments based in pharmacologic mechanisms are preferred. There are few controlled treatment trials and therapeutic efficacy generally is sought in a trial and error approach, depending on the type of nystagmus present. Treatment with 3,4-diaminopyridine and 4-aminopyridine recently have been shown to be effective for downbeat nystagmus. Gabapentin, baclofen, and clonazepam also are useful in some patients with downbeat nystagmus. Baclofen is the therapy of choice for periodic alternating nystagmus. Gabapentin often is effective for acquired pendular nystagmus. Clonazepam and valproate also may be effective for acquired pendular nystagmus. Memantine now is available in the United States and is promising in the treatment of pendular nystagmus. Optical devices that negate the negative effects of nystagmus continue to undergo development research. These and other medical, surgical, and optical devices are potentially useful alone or in combination with other therapies.

Infantile-onset nystagmus

PURPOSE OF REVIEW

Recent studies on the various forms of infantile-onset nystagmus have advanced our understanding of these disorders. The previously described waveforms of infantile nystagmus syndrome (congenital nystagmus) may be identified in infants less than 7 months of age, including the more mature forms; the visual status of these patients may be directly correlated with their mean foveation times.

RECENT FINDINGS

Refractive errors in patients with infantile nystagmus syndrome do not follow the expected trend toward emmetropization during infancy and early childhood. A study on the torsional component of nystagmus present in most patients with infantile nystagmus syndrome found it to be generated centrally and not by peripheral or mechanical dynamics. Two psychophysical studies on patients with infantile nystagmus syndrome revealed significant differences compared with control subjects. Two different animal models imply that lack of normal visual motion during a critical period of development in infancy leads to infantile nystagmus syndrome. An electron microscopic study of the enthesis site-where the extraocular muscle tendon inserts onto the sclera-in normal individuals versus patients with infantile nystagmus syndrome revealed significant abnormalities in the latter. Significant demographic and socioeconomic differences were reported between patients with infantile nystagmus syndrome and those with spasmus nutans.

SUMMARY

New evidence supports a role for sympathomimetic modulation of infantile nystagmus syndrome. Novel surgical treatments for infantile nystagmus syndrome are also discussed.