Subclinical histopathological changes in the oculomotor nerve in diabetes mellitus

Ocular motor nerve palsy in patients with diabetes: High-resolution MR imaging of nerve enhancement

OBJECTIVE

To evaluate the extent of signal abnormality in impaired ocular motor nerves using high signal and spatial resolution MRI sequences and to discuss the involvement of inflammatory or microvascular impairment in patients with diabetic ophthalmoplegia.

METHODS

We conducted a retrospective study of 10 patients referred for acute ocular motor nerve palsy in the context of diabetes mellitus from September 15th, 2021 to April 24th, 2022. 3T MRI evaluation included diffusion, 3D TOF, FLAIR, coronal STIR and post-injection 3D T1 SPACE DANTE sequences.

RESULTS

Ten patients were included: 9 males and 1 female aged from 46 to 79 years. Five patients presented with cranial nerve (CN) III palsy, and 5 presented with CN VI palsy. Third nerve palsy was pupil-sparing in 4 patients and pupil-involved in 1 patient. Pain was associated in all patients with CN III deficiencies and in 2 patients CN VI deficiencies. In all patients, MRI sequences ruled out mass effect and vascular pathology, such as acute stroke or aneurysm. Eight patients presented with STIR hypersignals, some with enlargement of the involved nerve. The diagnosis was confirmed through a post-injection 3D T1 SPACE DANTE sequence, which showed extended enhancement along the abnormal portion of the nerve.

CONCLUSION

High-resolution MRI evaluation of diplopia in diabetic patients is used to rule out a diagnosis of acute stroke and contributes to the positive diagnosis of ocular motor nerve impairment, possibly combining the influences of inflammatory and microvascular phenomena. Dedicated MR imaging should be included in the initial diagnosis and longitudinal follow-up of patients with diabetic ophthalmoplegia.

Keeping an eye on the diabetic foot: The connection between diabetic eye disease and wound healing in the lower extremity

Diabetic eye disease is strongly associated with the development of diabetic foot ulcers (DFUs). DFUs are a common and significant complication of diabetes mellitus (DM) that arise from a combination of micro- and macrovascular compromise. Hyperglycemia and associated metabolic dysfunction in DM lead to impaired wound healing, immune dysregulation, peripheral vascular disease, and diabetic neuropathy that predisposes the lower extremities to repetitive injury and progressive tissue damage that may ultimately necessitate amputation. Diabetic retinopathy (DR) is caused by cumulative damage to the retinal mic-rovasculature from hyperglycemia and other diabetes-associated factors. The severity of DR is closely associated with the development of DFUs and the need for lower extremity revascularization procedures and/or amputation. Like the lower extremity, the eye may also suffer end-organ damage from macrovascular compromise in the form of cranial neuropathies that impair its motility, cause optic neuropathy, or result in partial or complete blindness. Additionally, poor perfusion of the eye can cause ischemic retinopathy leading to the development of proliferative diabetic retinopathy or neovascular glaucoma, both serious, vision-threatening conditions. Finally, diabetic corneal ulcers and DFUs share many aspects of impaired wound healing resulting from neurovascular, sensory, and immunologic compromise. Notably, alterations in serum biomarkers, such as hemoglobin A1c, ceruloplasmin, creatinine, low-density lipoprotein, and high-density lipoprotein, are associated with both DR and DFUs. Monitoring these parameters can aid in prognosticating long-term outcomes and shed light on shared pathogenic mechanisms that lead to end-organ damage. The frequent co-occurrence of diabetic eye and foot problems mandate that patients affected by either condition undergo reciprocal comprehensive eye and foot evaluations in addition to optimizing diabetes management.

Painful ophthalmoplegia with normal cranial imaging

Background

Painful ophthalmoplegia with normal cranial imaging is rare and confined to limited etiologies. In this study, we aimed to elucidate these causes by evaluating clinical presentations and treatment responses.

Methods

Cases of painful ophthalmoplegia with normal cranial MRI at a single center between January 2001 and June 2011 were retrospectively reviewed. Diagnoses of painful ophthalmoplegia were made according to the recommendations of the International Headache Society.

Results

Of the 58 painful ophthalmoplegia cases (53 patients), 26 (44.8%) were diagnosed as ocular diabetic neuropathy, 27 (46.6%) as benign Tolosa-Hunt syndrome (THS), and 5 (8.6%) as ophthalmoplegic migraine (OM). Patients with ocular diabetic neuropathy were significantly older (62.8 ± 7.8 years) than those with benign THS (56.3 ±12.0 years) or OM (45.8 ± 23.0 years) (p < 0.05). Cranial nerve involvement was similar among groups. Pupil sparing was dominant in each group. Patients with benign THS and OM responded exquisitely to glucocorticoid treatment with resolved diplopia, whereas patients with ocular diabetic neuropathy didn’t (p < 0.05). Patients with OM recovered more rapidly than the other groups did (p < 0.05). Overall, most patients (94.8%) recovered completely during the follow-up period.

Conclusions

Ocular diabetic neuropathy and benign THS accounted for most of the painful ophthalmoplegias in patients with normal cranial imaging. Patient outcomes were generally good.

An updated definition of stroke for the 21st century: a statement for healthcare professionals from the American Heart Association/American Stroke Association

Despite the global impact and advances in understanding the pathophysiology of cerebrovascular diseases, the term "stroke" is not consistently defined in clinical practice, in clinical research, or in assessments of the public health. The classic definition is mainly clinical and does not account for advances in science and technology. The Stroke Council of the American Heart Association/American Stroke Association convened a writing group to develop an expert consensus document for an updated definition of stroke for the 21st century. Central nervous system infarction is defined as brain, spinal cord, or retinal cell death attributable to ischemia, based on neuropathological, neuroimaging, and/or clinical evidence of permanent injury. Central nervous system infarction occurs over a clinical spectrum: Ischemic stroke specifically refers to central nervous system infarction accompanied by overt symptoms, while silent infarction by definition causes no known symptoms. Stroke also broadly includes intracerebral hemorrhage and subarachnoid hemorrhage. The updated definition of stroke incorporates clinical and tissue criteria and can be incorporated into practice, research, and assessments of the public health.

Diabetic neuropathy part 2: proximal and asymmetric phenotypes

Diabetic neuropathies consist of a variety of syndromes resulting from different types of damage to peripheral or cranial nerves. Although distal symmetric polyneuropathy is the most common type of diabetic neuropathy, many other subtypes have been defined since the 1800s, including proximal diabetic, truncal, cranial, median, and ulnar neuropathies. Various theories have been proposed for the pathogenesis of these neuropathies. The treatment of most requires tight and stable glycemic control. Spontaneous recovery is seen in most of these conditions with diabetic control. Immunotherapies have been tried in some of these conditions however are controversial.

Diabetic neuropathy part 1: overview and symmetric phenotypes

Diabetes is the most common cause of neuropathy in United States and neuropathies are the most common complication of diabetes mellitus, affecting up to 50% of patients with type 1 and type 2 diabetes mellitus. Symptoms usually include numbness, tingling, pain, and weakness. Dizziness with postural changes can be seen with autonomic neuropathy. Metabolic, vascular, and immune theories have been proposed for the pathogenesis of diabetic neuropathy. Axonal damage and segmental demyelination can be seen with diabetic neuropathies. Management of diabetic neuropathy should begin at the initial diagnosis of diabetes and mainly requires tight and stable glycemic control.

Clinical characteristics and associated comorbidities in diabetic patients with cranial nerve palsies

BACKGROUND

Cranial mononeuropathy is one of the not so common forms of diabetic neuropathy that often appears to be a serious problem from a diagnostic and therapeutic point of view.

AIM

Objective of this study was to determine the incidence, the clinical characteristics, and risk factors associated with cranial nerve palsies among persons with diabetes.

METHODS

We have performed a retrospective study of all diabetic patients with cranial nerve palsies who were hospitalized in a metabolic department over a 12-yr period.

RESULTS

During the period of the survey, a total of 8150 diabetic subjects were hospitalized and cranial nerve palsies were identified in 61 patients (0.75%). Isolated III nerve palsies accounted for the majority of patients (0.35%), with VII nerve palsies (0.21%) occurring more frequently than VI (0.15%) and multiple palsies (0.04%). Peripheral neuropathy was present in only 24% of patients. Patients with VII nerve palsies showed a tendency toward a lower coexistence of diabetic complications and cardiovascular risk factors than those with III and VI nerve palsies.

CONCLUSIONS

Cranial nerve palsies are a not common problem among patients with diabetes; diagnosis of diabetic mononeuropathy should be considered even in the absence of peripheral neuropathy; the oculomotor nerve was most frequently affected in our case report. The coexistence of diabetic complications and cardiovascular risk factors was slightly lower in patients with VII nerve palsy: this fact is compatible with the hypotesis that this event is less closely related to diabetes and metabolic factors in its pathogenesis.

Ophthalmoplegia in diabetes mellitus: a retrospective study

Ophthalmoplegia, despite being a rare entity in diabetes mellitus, is associated with great anxiety for the patients and often appears to be a serious problem from a diagnostic and therapeutic point of view. There have been few studies primarily concerned with the relative frequencies and clinical characteristics of oculomotor neuropathies in diabetic subjects. Those published have emanated largely from neurological and/or ophthalmological referral centres rather than metabolic departments. Objective of this study was to determine the incidence, the clinical characteristics and risk factors for developing ophthalmoplegia among persons with diabetes mellitus. We have performed a retrospective study of all diabetic patients with ophthalmoplegia who were seen in the Metabolic Division at "S. Biagio" Hospital, Marsala, over the 10 year period from 1998 to 2007. A detailed history and blood laboratory profile were obtained for each patient. During the period of the survey a total of 6,765 diabetic subjects were hospitalised and ophthalmoplegia was identified in 27 patients (0.40%). Isolated III nerve palsies accounted for the majority of patients (59.3%), with VI nerve palsies (29.6%) occurring more frequently than multiple palsies (11.1%). These patients had a marked comorbidity and were found to have a poorly controlled diabetes. The patients with VI nerve palsies showed a tendency toward a higher coexistence of diabetic retinopathy and cardiovascular risk factors than those with III cranial nerve palsies. Ophthalmoplegia is a serious and not common problem among patients with diabetes mellitus; the oculomotor nerve was most frequently affected in our case-report. The fact that the coexistence of diabetic complications and cardiovascular risk factors was slightly higher in patients with VI nerve palsy is compatible with the hypothesis that this ischemic event might be more closely related to diabetes and metabolic syndrome in its pathogenesis.

Retinopathy in patients with diabetic ophthalmoplegia

PURPOSE

To review the clinical characteristics, prevalence, and severity of retinopathy in diabetics with cranial nerve (CN) 3, 4, and/or 6 palsies, and to determine the relationship between type and duration of diabetes mellitus (DM), presence of retinopathy, and occurrence of CN palsy.

DESIGN

Retrospective, comparative cohort study.

PARTICIPANTS

Chart reviews of 2229 patients with CN 3, 4, and/or 6 palsies were performed at the Bascom Palmer Eye Institute (BPEI) from January 1991 through December 1997 and at the Dean A. McGee Eye Institute (DMEI) from January 1994 through July 2001. A total of 306 patients qualified for the study group. The Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) was used as a control.

METHODS

Demographic and clinical data were extracted to determine characteristics of patients with diabetic ophthalmoplegia. The subsets of data regarding type of DM and level of diabetic retinopathy in the study population were compared with the WESDR control data for statistical analysis.

MAIN OUTCOME MEASURES

The prevalence of diabetic retinopathy in patients with diabetic ophthalmoplegia.

RESULTS

Of 2229 patients at both institutions with ocular motor CN palsy, 306 (13.7%) were associated with DM. The frequency of CN involvement was 6 (50.0%), 3 (43.3%), and 4 (6.7%). There was a total of 12 patients (3.9%) with consecutive palsies and 8 patients (2.6%) with simultaneous palsies (5 unilateral and 3 bilateral). At both institutions, the prevalence of retinopathy controlling for duration of DM was lower in both insulin-dependent DM (IDDM) and non-IDDM (NIDDM) type II diabetics as compared with controls (BPEI, P = 0.009 and P = 0.005; DMEI, P = 0.004 and P = 0.29). When data from both locations were combined, the difference was even more significant (IDDM, P = 0.001 and NIDDM, P = 0.006). There were no significant differences between the two institutions in gender, type or duration of DM, age at presentation, or frequency of CN involvement.

CONCLUSIONS

Diabetic ophthalmoplegia most commonly involves CN 3 and 6, with relative sparing of CN 4. Multiple cranial nerves are affected simultaneously in 2.6% of cases, and consecutive palsies occurred in 3.9% of cases. Type II diabetics with ocular motor CN palsy have significantly less diabetic retinopathy than do controls. This may imply a different pathophysiologic mechanism for these two microvascular complications of DM.

Focal and multifocal neuropathies

The focal and multifocal neuropathies affect only a minority of patients with diabetes; however, they form a major clinical problem in terms of diagnosis, development of significant symptoms and signs, and often inadequate therapy. Diagnosis requires accurate and detailed clinical history and neurologic examination combined with targeted neurophysiologic tests, which differ considerably from those carried out in day-to-day practice. Because of their relatively infrequent occurrence, treatment is not evidence based.

Trigeminal small-fibre dysfunction in patients with diabetes mellitus: a study with laser evoked potentials and corneal reflex

OBJECTIVE

To investigate trigeminal small-fibre function in patients with diabetes mellitus.

METHODS

In 52 diabetic patients we studied the trigeminal laser evoked potentials after stimulation of the skin bordering the lower lip. In the 21 patients with the severest peripheral nerve damage we also studied the electrically evoked corneal reflex. Both responses are mediated by small myelinated afferents.

RESULTS

Laser evoked potentials had a longer mean latency and lower amplitude in diabetic patients than in normal subjects (P<0.005). The abnormality frequency of the laser evoked potentials correlated with the severity of polyneuropathy (P<0.005). In contrast, the corneal reflex was normal.

CONCLUSION

Dysfunction of small afferents of the mandibular nerve is frequent in patients with diabetic polyneuropathy. We speculate that the primary cause could be segmental demyelination.

Diabetic neuropathy

The most common form of diabetic neuropathy is chronic, distal symmetrical sensorimotor, or predominantly sensory neuropathy; the latter is invariably associated with some degree of autonomic dysfunction. There are, however, other neuropathic patterns in diabetes mellitus that are uncommon but are important to recognize, since they may mimic many other non-neurologic diseases. This article discusses a variety of forms of mononeuropathies and diabetic proximal motor neuropathy, commonly known as diabetic amyotropy.

Oculomotor nerve and muscle abnormalities in congenital fibrosis of the extraocular muscles

Congenital fibrosis of the extraocular muscles is an autosomal dominant congenital disorder characterized by bilateral ptosis, restrictive external ophthalmoplegia with the eyes partially or completely fixed in an infraducted (downward) and strabismic position, and markedly limited and aberrant residual eye movements. It has been generally thought that these clinical abnormalities result from myopathic fibrosis of the extraocular muscles. We describe the intracranial and orbital pathology of 1 and the muscle pathology of 2 other affected members of a family with chromosome 12-linked congenital fibrosis of the extraocular muscles. There is an absence of the superior division of the oculomotor nerve and its corresponding alpha motor neurons, and abnormalities of the levator palpebrae superioris and rectus superior (the muscles innervated by the superior division of the oculomotor nerve). In addition, increased numbers of internal nuclei and central mitochondrial clumping are found in other extraocular muscles, suggesting that the muscle pathology extends beyond the muscles innervated by the superior division of cranial nerve III. This report presents evidence that congenital fibrosis of the extraocular muscles results from an abnormality in the development of the extraocular muscle lower motor neuron system.