Horizontal gaze-evoked nystagmusWallenberg syndrome is caused by an ischemia of the dorsolateral medulla oblongata, which belongs to the vascular territory of the vertebral artery or posterior inferior cerebellar artery (PICA). Like other forms of stroke, this condition should always be treated as an emergency.
Signs and Symptoms
The leading symptom of Wallenberg syndrome is acute vertigo with a tendency to fall toward the affected side. In addition there are often double vision, impaired sensation in the face and body, dysphagia, hoarseness, slurred speech or hemiataxia. The torso and extremities on the opposite side of the infarction and/or the face and cranial nerves on the same side as the infarction may be affected by sensory deficits including loss of pain and temperature sensitivity and cerebellar ataxia. Patients also often present with a Horner’s syndrome (unilateral ptosis, miosis and enophthalmus).
Observable ocular motor disorders
- Ocular tilt reaction, i.e. skew deviation/vertical divergence, head tilt, ocular torsion and a deviation of subjective visual vertical
- Nystagmus toward the non-affected side
- Hypermetric saccades to the side of the lesion, hypometric saccades towards the non-affected side
- “Lateropulsion” of vertical saccades
- Horizontal gaze-evoked nystagmus
Patient looks straight ahead: mainly horizontal spontaneous nystagmus beating to the left. Examination in darkness shows the spontaneous nystagmus to the left and the myosis on the right side with a slight ptosis, typical of right-sided Horner syndrome.
0.10 Cover test: skew deviation, left eye above the right eye, typical of one of the components of the ocular tilt reaction. 0.40 Alternating cover test shows the maximum angle of skew deviation. 0.52 Convergence reaction normal. 0.57 Looking for gaze-evoked nystagmus, looking to the right and upward. 1.08 Looking for gaze-evoked nystagmus to the left. 1.18 Looking for gaze-evoked nystagmus downwards. Showing the spontaneous nystagmus beating to the left. 1.30 Smooth pursuit: saccadic, in particular to the left. 1.40 Also vertically saccadic. 1.50 Examination of saccades: hypermetric to the right and hypometric to the left, typical finding in Wallenberg’s syndrome. 2.00 Vertical saccades: lateropulsion to the right when looking upward, typical of right-sided Wallenberg’s syndrome. 2.33 Determination of subjective visual vertical shows a clear deviation of the subjective visual vertical to the right, another component of the ocular tilt reaction to the right. 0.25 When looking straight ahead, there is a mainly torsional nystagmus upper pole beating to the right. When examining the patient with Frenzel’s glasses, the Horner syndrome on the left and the skew deviation with the left eye below the right eye can also be better seen. 0.38 This is a typical central fixation nystagmus which cannot be suppressed by visual fixation. 0.48 Cover test reveals that the left eye is below the right eye, i.e. a skew deviation. 1.00 The maximum angle of eye deviation can be identified by the alternating cover test. 1.15 There is a strong tendency of the patient to fall to the left, typical of a left-sided Wallenberg’s syndrome with strong lateropulsion.
Patient looks straight ahead: mainly horizontal spontaneous nystagmus beating to the left.
Examination in darkness shows the spontaneous nystagmus to the left and the myosis on the right side with a slight ptosis, typical of right-sided Horner syndrome.
Strupp M, et al. Central ocular motor disorders, including gaze palsy and nystagmus. J Neurol 2014, 261(2):542-558. PubMed