Ptosis

Ptosis is manifested by pathological drooping of the upper eyelid, limiting the opening of the eye. It can be unilateral or bilateral and is observed in:

1. Lesions of the striated muscle that lifts the upper eyelid (m. levator palpebrae superior).
2. Damage to the nerve that innervates this muscle (the oculomotor nerve or its nucleus).
3. Apraxin for eye opening in Parkinsonism syndrome and other diseases.
4. Disruption of autonomic innervation of smooth muscle fibers of the superior tarsal muscle (Horner's syndrome).
5. False impression of ptosis (apparent ptosis) due to retraction of the eye or exophthalmos on the opposite side.

Thus, there are three possible causes of true ptosis: partial damage to the oculomotor nerve (the branch that innervates the muscle that lifts the upper eyelid) or its nucleus; damage to the sympathetic pathway (weakness of the tarsal muscle) and myopathy. Unilateral ptosis indicates the presence of a limited focal lesion of the nervous system. Bilateral ptosis is almost always a sign of diffuse muscle pathology or, much more rarely, a disease of the peripheral nervous system. The first point of the diagnostic algorithm is to determine the presence or absence of mild weakness of other external eye muscles in a patient with ptosis, the second point is to examine the width of the pupils and photoreactions. Detection of miosis with preservation of eye movements indicates the presence of Horner's syndrome in the patient and allows us to exclude damage to the third cranial nerve. Slight dilation of the pupil and weakening of the direct reaction of this pupil to light is characteristic of damage to the third cranial nerve and allows us to exclude both Horner's syndrome and myopathy. Of course, there are cases of damage to the third cranial nerve, when the parasympathetic fibers remain intact. In myopathy, in addition to ptosis, weakness of other eye muscles, facial muscles and (or) muscles of the extremities is often detected.

Naturally, this article overlaps in content to a large extent with the chapter on acute paresis of the external eye muscles. Therefore, some sections of this chapter are presented rather briefly and are intended mainly to draw attention to ptosis as a symptom that is often detected only during a medical examination and is rarely an active complaint of the patient himself. If ptosis develops gradually, some patients are not even able to say whether they had drooping eyelids (lids) from birth or whether it arose at a certain age.

A. Unilateral

1. Lesion of the oculomotor sympathetic innervation (Horner's syndrome)
2. Midbrain tegmental lesions
3. Damage to the trunk of the third nerve
4. Intraorbital tumor and pseudotumor
5. Congenital ptosis

B. Double-sided

1. Congenital
2. Myopathy
3. "Ophthalmoplegia Plus"
4. Myasthenia
5. Midbrain tegmental lesions
6. Hereditary metabolic neuropathies (Refsum disease, Bassen-Kornzweig disease)
7. Apraxia of eyelid opening (including idiopathic blepharospasm)

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Ptosis as a symptom of damage to different levels of the nervous system and muscles

A. Supranuclear level

Supranuclear level (If this level is affected, ptosis can be unilateral or bilateral).

1. Unilateral ptosis: ischemic infarction in the middle cerebral artery basin of the contralateral hemisphere (most often), tumor, arteriovenous malformation.
2. Bilateral ptosis: may be observed with unilateral (most often right-hemisphere) and bilateral hemisphere damage. Bilateral ptosis with downward gaze paralysis has been described with midbrain glioma.
3. "Ptosis" (not true) in the picture of apraxia of eyelid opening: with damage to the right hemisphere or bilateral damage to the hemispheres, with extrapyramidal disorders such as Huntington's chorea, Parkinson's disease, progressive supranuclear palsy, amyotrophic lateral sclerosis, Shy-Drager syndrome, neuroacancytosis, Wilson's disease. Dopa-sensitive apraxia of eyelid opening in the absence of any other symptoms of CNS damage has been described.
4. Psychogenic ptosis (usually manifests itself not as true ptosis, but as psychogenic blepharospasm).
5. Ptosis in the picture of Duane's syndrome. The syndrome is usually unilateral.

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B. Nuclear, root and axonal (oculomotor nerve) levels

Lesions at these levels are usually accompanied by other oculomotor disturbances (eg, mydriasis). Lesions at the nuclear level may be accompanied by bilateral ptosis.

It occurs in diseases manifested by superior orbital fissure syndrome, orbital apex syndrome, cavernous sinus syndrome, lacerated foramen syndrome and brainstem syndromes in tumors, injuries, inflammatory processes, aneurysms, hyperostoses and other diseases of the skull and brain.

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C. Synaptic and muscular levels

Synaptic and muscular levels: myasthenia, botulism, ocular myopathy, dysthyroid orbitopathy, polymyositis, intraorbital processes mechanically damaging the levator glabellar muscle, involutional ptosis in the elderly, congenital ptosis.

Intermittent ptosis with diplopia has been described in hereditary motor-sensory polyneuropathy types I and II (Charcot-Marie-Tooth amyotrophy); slowly progressive ptosis may develop in diabetes, with local damage to the levator palpebrae or smooth tarsal muscles (or both) due to local ischemia or hypoxia. Rarely, ptosis, unilateral or bilateral, may be observed in the picture of Miller Fisher syndrome.

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A. Unilateral ptosis

Horner's syndrome. This form of ptosis (paralysis of the smooth superior tarsal muscle), together with more or less pronounced miosis (paralysis of the muscle that dilates the pupil), decreased conjunctival hyperemia (vasomotor paralysis), enophthalmos (the presence of this symptom is not at all obligatory), often with impaired sweating on the upper half of the body, make up Horner's syndrome. It should be taken into account that in Horner's syndrome the difference in the width of the palpebral fissure decreases when looking upward (since the intact and strong striated m. levator palpebrae superior is activated).

Horner's syndrome may be a consequence of:

Damage to the homolateral central sympathetic pathways running between the hypothalamus, the postero-external parts of the medulla oblongata and the lateral columns of the spinal cord. The following causes always lead to Horner's syndrome, as well as other disorders of the central nervous system:

• vascular strokes, especially in the brainstem, such as:
  • Wallenberg-Zakharchenko syndrome.
  • tumors syringomyelia
  • progressive hemifacial atrophy

Lesions of the paravertebral sympathetic chain and its radicular afferents.

If a separate component of the paravertebral sympathetic chain is affected, there will be no functional disorders of the nervous system. However, if the stellate ganglion is affected, Horner's syndrome is accompanied by facial anhidrosis. Horner's syndrome is not observed when the (ventral) roots from C8 to T12 are affected (radicular disorders are detected). If the paravertebral sympathetic chain is affected immediately caudal to the stellate ganglion, isolated facial anhidrosis without Horner's symptom is observed. Possible causes are:

• tumor impact on the paravertebral sympathetic chain (often accompanied by dysfunction of the brachial plexus);
• damage to the roots or chain due to trauma (rupture of the roots with the formation of lower brachial plexopathy as a radicular syndrome C8 - T1; prevertebral hematoma);
• cluster headache, which is often accompanied by Horner's syndrome.

Damage to the midbrain tegmentum, which contains the nuclear complex of the third cranial nerve, can lead to various neurological syndromes depending on the localization of the brain lesion. In these cases, ptosis, as a symptom of damage to the third nerve, is usually accompanied by other symptoms of damage to the oculomotor nerve, as well as nearby formations of the oral sections of the brainstem. In order for damage to the midbrain tegmentum to manifest itself only as ptosis, it must be so small (for example, a small lacuna) that it affects only the nuclei and fibers going to m. levator palpebrae superior and does not affect nearby structures. Such a situation is sometimes observed with damage to small vessels of the brainstem (usually in patients suffering from arterial hypertension). In slowly developing processes affecting the nucleus of the oculomotor nerve, ptosis often appears after paresis of the external eye muscles ("the curtain falls last"). In addition, in each such case, ptosis will be accompanied by symptoms of damage to other cranial nerves and/or conductors of the brain stem (and is often bilateral).

Unilateral ptosis, as a symptom of damage to the trunk of the third nerve at the base of the brain, is also observed in the picture of the following syndromes:

Superior orbital fissure syndrome: III, IV, VI nerves + VI (first branch of the trigeminal nerve). The most common causes: pterygoid tumors, parasellar tumors, periostitis, osteomyelitis, leukemic or granulomatous infiltration in the superior orbital fissure area. Rollet's orbital apex syndrome: III, IV, VI nerves + II nerve. Causes: space-occupying processes behind the eyeball (retrobulbar).

Cavernous sinus syndrome of Bonnet {strongonnet}: III, IV, VI nerves + VIi, exophthalmos and chemosis (hyperemia and edema of the conjunctiva and eyelids). Causes: cavernous sinus tumors, carotid artery aneurysm, cavernous sinus thrombosis. Cavernous sinus lateral wall syndrome of Foix {Foix}: III, IV, VI nerves + VI (first branch of the trigeminal nerve). Causes: pituitary tumors, internal carotid artery aneurysm, purulent processes in the cavernous sinus, cavernous sinus thrombosis.

Jefferson's foramen lacerum syndrome: III, IV, VI nerves + VI. (Internal carotid artery aneurysm)

Intraorbital tumor and pseudotumor. The latter term is intended to denote enlarged (due to inflammation) extraocular muscles and sometimes other orbital contents. Orbital pseudotumor is accompanied by conjunctival injection and mild exophthalmos, retroorbital pain, which can sometimes simulate migraine or cluster headache. Ultrasound or CT of the orbit reveals an increase in the volume of orbital contents, mainly muscles, similar to what is found in dysthyroid ophthalmopathy. Both Tolosa-Hunt syndrome and orbital pseudotumor respond to treatment with corticosteroids. Orbital tumor, in addition to the above symptoms, is also accompanied by compression of the second pair and, consequently, a decrease in visual acuity (Bonnet orbital apex syndrome).

Congenital unilateral ptosis may be a manifestation of the Gunn phenomenon, which is based on pathological connections between neurons that provide for the lifting of the upper eyelid and chewing. In this case, the drooping upper eyelid (usually the left one) rises when opening the mouth or when moving the lower jaw in the direction opposite to ptosis.

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B. Bilateral ptosis

Congenital ptosis, sometimes unilateral, is present from birth, does not progress, and may be accompanied by weakness of the external eye muscles. Bilateral disorders are often familial, with a typical posture of the head tilted backwards.

Myopathy (oculopharyngeal muscular dystrophy) is characterized by late onset (in the 4th-6th decade of life) and manifests itself in damage to the extraocular muscles (including ptosis), as well as the muscles of the pharynx with impaired swallowing. There is also a form with isolated damage to only the extraocular muscles, which, gradually progressing, eventually leads to complete external ophthalmoplegia. As a rule, a certain degree of weakness of the facial muscles is also detected. Ophthalmoplegia usually occurs without double vision (ocular myopathy, or progressive external ophthalmoplegia). The diagnosis is confirmed by EMG testing. The CPK level rarely rises (if the process spreads to other striated muscles). Less often, other forms of myopathy lead to ptosis.

"Ophthalmoplegia plus" or Kearns-Sayre syndrome is characterized by progressive external ophthalmoplegia and ptosis. The syndrome is related to mitochondrial encephalomyopathies and is more often observed in sporadic cases (although there is also a familial variant of progressive external ophthalmoplegia) and, typically, is accompanied by the involvement of many organs and systems. The disease begins before the age of 20. Obligatory signs of this disease are: external ophthalmoplegia, cardiac conduction disorders, pigmentary degeneration of the retina, increased protein content in the cerebrospinal fluid. Other additional symptoms include ataxia, hearing loss, multiple endocrinopathy, and other manifestations. With the familial variant of progressive external ophthalmoplegia, manifestations of weakness in the muscles of the neck and limbs are possible.

Myasthenia. If myasthenia is suspected, a simple clinical test should be performed to detect pathological muscle fatigue - the patient is asked to perform the affected movements 30-40 times (or less) in a row. In this case, closing and opening the eyes. If this test reveals an increase in ptosis (bilateral or unilateral), then pharmacological tests should be performed. Intramuscular injections of anticholinesterase drugs (for example, prozerin) lead to the elimination of ptosis in 30 seconds - 2 minutes for a period of several minutes to half an hour. The longer the recovery period, the less typical it is for myasthenia, and should be the basis for continuing the diagnostic search.

Damage to the midbrain tegmentum at the level of the nucleus of the third nerve may be accompanied by bilateral ptosis and other symptoms of damage to the oculomotor nerves and the underlying conductors of the brainstem.

Ptosis may be a manifestation of rare hereditary metabolic neuropathies, such as Refsum disease or Bassen-Kornzweig disease. The accompanying decrease or disappearance of tendon reflexes, as well as a slowdown in the speed of excitation conduction along the nerve, indicate damage to the peripheral nerves. The search for metabolic disorders determines the success of the diagnosis.

Apraxin of eyelid opening can (rarely) imitate bilateral ptosis in patients with Parkinson's disease, Huntington's chorea and other extrapyramidal diseases (see below), including facial paraspasm (a combination of apraxia of eyelid opening and blepharospasm has been described).

Additional assistance in assessing the nosological affiliation of ptosis can be provided by the information below about its characteristics when various levels of the nervous system are affected.

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