Ординатура / Офтальмология / Английские материалы / Clinical Neuro-ophthalmology A Practical Guide_Schiefer, Wilhelm , Hart_2007

Video 21.1

with plantar flexion and a partially supinated foot, forcing the patient’s movement of the leg into an arc that swings out to

• Pearl

Pareses of analyzed by strength testing of individual muscle groups usually allows for a rapid classification of the locus of disease to nerve root, plexus, or peripheral nerve. Additional clues are provided by accompanying disturbances of sensory function and testing of reflexes.

• Pearl

During a quick survey, or when examining patients that are only poorly cooperative, testing of pain sensation (with a needle or a toothpick) provides the most useful information.

From the topography and the quality of sensory disturbances, one can frequently reach an accurate conclusion as to the localization and etiology of the neural pathology. Typical examples are illustrated in ■ Fig. 21.7.

Clinical Testing of Reflexes

In general a minimal neurologic examination should include the most important arm and leg reflexes (■ Tables 21.13, 21.14, and 21.15), as well as testing of the presence of one of the Babinski signs. Deep tendon reflexes should be tested in positions that allow maximal relaxation of the involved muscle groups. This is most likely to be the case with the patient in the recumbent position. If muscular tension is fully excluded, and the patient still has absent or very weak deep tendon reflexes, facilitation maneuvers are often helpful, such as clenching the teeth during tests of arm reflexes and grasping both hands together while exerting maximal effort at pulling them apart (Jendrassik’s maneuver), during the testing of leg reflexes.

sensation with lesions of the contralateral cerebral hemisphere. b Loss of sensory perception in both legs with transverse damage to the spinal chord. c Glove-and-stocking pattern of sensory loss associated with a polyneuropathy

Deep tendon reflexes are variably elicitable under normal circumstances among patients in general. They can be quite weak in some patients, and lively in others. In order to identify correctly pathological weakening, care should be taken to compare one side to the other, to compare leg reflexes with those of the arm, or the arm and leg reflexes to those of the masseter. Pathological weakening of these reflexes should be diagnosed only when a clear and definite departure from normal can be detected.

Clinical Testing of Coordination – Ataxia

:Definition

Disturbances of coordination, i.e., of smoothly cooperative alternation of agonists and antagonists during the course of complex movements like walking, are in general referred to as ataxia.

Corneal reflex Oligosynaptic reflex, afferent path in the first (ophthalmic) division of the trigeminal nerve, efferent path via the facial nerve, synapses located in pontomedullary brainstem

Touch cornea with a cotton wisp that is not visible to the patient, response is a blink produced by a contraction of the orbicularis oculi

Attenuation caused specifically by lesions of the trigeminal

or facial nerve or their central synaptic connection

Abnormal rebound movement is found in patients with cerebellar dysfunction: The arm rises uncontrollably.

Unsteadiness (standing ataxia) with cerebellar disease Increasing with eyes closed, when there is also

loss of sensory afferent control (loss of proprioception and touch sensations).

Normal coordination depends on the simultaneous participation in the function of multiple neuronal systems (■ Table 21.16). Among these are the cerebral hemispheres, the cerebellum, the spinal, extrapyramidal, and vestibular systems, as well as the afferents and efferents of the peripheral nervous system.

Disturbances of Cerebellar Function

Cerebellar disorders are detected most sensitively with tests of coordination (■ Table 21.17). Important clinical signs of cerebellar dysfunction have been described in patients with multiple sclerosis with the so-called Charcot’s triad: intention tremor, nystagmus, and scanning speech.

Conclusion

When visual changes are thought to be caused by a disease process affecting the nervous system, the ophthalmologist should, as a “non-neurologist,” be able to elicit important clinical signs that will help to clarify the neurological diagnosis. This should help reduce the number of suspected disorders in the differential diagnosis, and by eliminating some possibilities, will facilitate the planning of further diagnostic procedures. This is especially important when assessing the level of urgency associated with the findings, and to participate in the strategic planning of the patient’s further care.

Further Reading

Delank HW, Gehlen W (2006) Neurologie. Thieme, Stuttgart

Duus P (2001) Neurologisch-topische Diagnostik. Thieme, Stuttgart Mumenthaler M (1993) Klinische Untersuchung und Analyse neurolo-

gischer Syndrome. Thieme, Stuttgart

Mumenthaler M (1997) Neurologische Differentialdiagnostik. Thieme, Stuttgart

Poeck K, Hacke W (2006) Neurologie. Springer, Berlin Heidelberg New York

Schenck E (1992) Neurologische Untersuchungsmethoden. Thieme, Stuttgart

Tumors Compromising the Visual Pathway

When visual loss is associated with a mass lesion, the physician in charge has to consider a large variety of aspects such as the biological nature and the location of the lesion. Is the tumor extra-axial, i.e., originating in the vicinity of the optic system and compressing it, or is it intra-axial, i.e., arising from the visual pathway itself? Is the lesion slow or fast growing? Does it threaten the patient’s life? What is the probable time course of further deficits to be expected? Can the lesion be removed completely, or does the surgery have to be limited to decompression of the visual pathways? Furthermore, the surgical accessibility and appropriate operative approach has to be considered in terms of adequate tumor exposure and minimal invasiveness with satisfying cosmetic results at the same time. Which additional imaging and electrophysiological information is available to increase the safety of the intervention?

The intention of the following chapter is to address these questions for the most frequent tumors of the orbita, anterior skull base, sellar/parasellar region, and intraparenchymal hemispheres that compromise visual function, and to introduce the required neurosurgical techniques including intraand extracranial approaches to treat these lesions.

Intraorbital Lesions

:Definition

Intraorbital tumors include optic nerve sheath meningeomas, optic nerve gliomas, cavernous hemangiomas, peripheral nerve tumors, dermoid and epidermoid cysts, osteomas, fibrous dysplasia, hemangiopericytoma, metastatic lesions, and less frequent pathologies.

!Note

Orbital tumors that are located lateral to the nerve may be resected via a lateral orbitotomy. Lesions superior to the optic nerve are removed using an orbitofrontal craniotomy. When the tumor is located below the nerve or medially, a transethmoidal or transmaxillary approach or a transconjunctival approach can be chosen.

Optic nerve sheath meningeomas (■ Fig. 22.1) may be treated with a variety of modalities, depending on the current visual status of the patient. If vision is lost completely, the tumor can be removed totally. When useful visual function is present, fractionated stereotactic radiotherapy is the method of choice (see Chap. 23). From the neurosurgical point of view a histological confirmation should precede this therapeutic option.

Fig. 22.5 CT images of a trauma patient presenting with a fracture of the orbital roof (a) with secondary visual deficit in the same side and an associated intracranial hematoma above the orbit (b). This constellation allows decompressing the orbit and evacuating the hematoma during one surgery

Anterior Skull Base Tumors

Meningiomas of the sphenoidal wing, the anterior clinoid, and the cavernous sinus may involve the optic canal and the superior orbital fissure (■ Fig. 22.6) as well as the intracranial optic nerves and optic chiasm.

!Note

Frontolateral or pterional craniotomies allow exposure and removal of these lesions with good functional outcome.

Fig. 22.6. Meningioma of the left clinoid process in axial (a) and coronal (b) planes of contrast-enhanced T1-weighted MR images. Patient positioning and skin incision behind the hairline for a frontolateral approach to remove this lesion (c)