BROAD THUMBS AND TOES, AND UNUSUAL FACIAL FEATURES; A PROBABLE MENTAL RETARDATION SYNDROME.
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We investigated the mechanism involved in paraesthesia associated with sagittal split mandibular ramus osteotomy by three-dimensional computed tomography (3-D CT). Ten female patients underwent this procedure between 1988 and 1991. The inferior alveolar neuro-vascular bundles remained intact during the sagittal osteotomy in all cases. We examined the changes in the shape of the foramen mandibulae over a period of 6 months during which the transient mental nerve paraesthesia was recovered, and studied the distance from the foramen mandibulae to the spina mentalis (F-S distance) as measured on 3-D film. The postoperative 3-D CT scan showed bone resorption in front of the foramen mandibulae, and the F-S distance was shortened by an average of 2.94 mm. These findings suggest that possible causes of the paraesthesia is due to compression of the nerve trunk resulting from posterior movement of the mandibular ramus.
We describe a technique for sensory nerve conduction study of the mental nerve. A monopolar recording needle is placed near the mandibular foramen using the same approach as that for routine inferior alveolar nerve block in dentistry, and a surface reference electrode is positioned over the ipsilateral mastoid process. Sensory nerve action potentials to stimulation of the mental nerve at the chin can be reliably recorded orthodromically in normal healthy subjects. The method is simple and well tolerated and provides a useful means to evaluate mental nerve function electrophysiologically.
Patients who had uncontrolled pain with carbamazepine therapy and those who suffered adversely from its side effects were selected for this safe, simple and repeatable surgery. Pain-free periods were achieved for at least 2 years. Functional difficulty was not experienced in the affected numb areas. When it recurred, pain was less intense and was better controlled with a reduced dosage of carbamazepine. In four cases, after avulsion of the involved nerves, a suitable-sized titanium screw was inserted into the mental and infra-orbital foramina. Obturation of the foramen prevented nerve regeneration, which further prolonged the pain remission period.
In 20 subjects, we stimulated the mental nerve through needle electrodes inserted into the homonymous foramen; recording electrodes were placed on the scalp and along the jaw. Within the 1st 5 msec after the stimulus we recorded 4 constant waves, thought to reflect the afferent activity from the mandibular nerve up to the trigeminal nuclei. These waves have similar characteristics and the same high degree of reliability as those obtained after stimulation of the infraorbital and supraorbital nerves; therefore, they should be a useful complement for a complete exploration of trigeminal nerve function.
Thirteen infants with achondroplasia underwent psychometric testing as part of a comprehensive neurologic assessment. As a group, mental development was average and motor development was delayed, although a wide range of scores was obtained. Foramen magnum measurements were correlated with respiratory dysfunction, abnormal somatosensory evoked potentials, and delayed motor development. Abnormal polysomnogram outcome was associated with reduced mental capacity. In light of the reported increased frequency of respiratory dysfunction in achondroplasia, these findings warrant careful attention and further study.
BACKGROUND: The anterior mandible is generally considered a rather safe surgical area, involving few risks of damage to vital anatomic structures. Nevertheless, both neurosensory disturbances and hemorrhages have been reported after implant surgery in that particular area. PURPOSE: With the increasing demand for oral implant placement, the anatomy of the anterior mandible should receive more attention. This review will focus on the anatomic peculiarities of the anterior mandible and the related clinical implications. METHODS: The scientific evidence on the anatomic, histologic, physiologic, and clinical aspects of the neurovascularization of the anterior mandible will be reviewed. RESULTS: Surgical complications may be attributed to the existence of a mandibular incisive canal with a true neurovascular supply. Potential risks may also be related to the presence of the lingual foramen and anatomic variations, such as an anterior looping of the mental nerve. CONCLUSIONS: Preoperative radiographic planning for oral implant placement in the anterior mandible should therefore not only consider all esthetic and functional demands but should also pay particular attention to the anatomic peculiarities of this region to avoid any neurovascular complications.
The rodent dentition has become an important model for investigations of interactions between dental tissues and peripheral neurons. Although experimental nerve injury has been widely used for such studies, there is uncertainty about the courses of nerve fibers supplying the mandibular teeth. In order to clarify this, we used a mixture of monoclonal antibodies against neurofilament proteins to enhance demonstration of nerve fibers so that small nerves could be readily traced in serial frozen sections of mandibles of Sprague Dawley rats ranging in age from embryonic day (E) 18 to postnatal day (P) 90. The 1st molar and anterior portion of the 2nd molar were innervated by small nerves that emerged as distinct branches of the IAN trunk at or near the mandibular foramen. In contrast, the nerve supply to the 3rd molar and posterior part of the 2nd molar was a branch of the lingual nerve that bypassed the mandibular canal altogether. The IAN trunk split into the mental nerve and a large branch to the incisor about 2 mm anterior to the mandibular foramen. Thick branches of the incisor nerve descended into the incisor socket to form a dense plexus of nerve fiber bundles extending along the length of the incisor periodontium. The sparse pulpal innervation of the incisor was provided by a few thin fascicles that emerged from the caudal portion of the periodontal plexus to enter the incisor apex. The dental branches of the IAN and lingual nerve seen in the adult were well established and readily identifiable at age E18 even though their targets were limited to the follicles of the developing teeth. These studies show that the trigeminal branches that supply the mandibular teeth can be identified at a wide range of ages as distinct nerves at a considerable distance proximal to their targets. This detailed information on the courses taken by the dental nerves can provide an anatomical basis for increased precision in characterization and perturbation of neural pathways from the molars and incisor.
The retromolar foramen (RMF) was found to occur in eighteen of 234 adult human mandibles studied (7.7%). No statistically significant difference was found between left and right sides or between sexes. A statistical correlation was made between the occurrence of the RMF and accessory mandibular foramina, accessory mental foramina, mandibular third molars, and three-rooted mandibular first molars. Only the accessory mandibular foramen showed a significant positive correlation with RMF regarding same-side occurrence. Three-rooted first molars were not found in any of the mandibles studied. Due to the relatively frequent occurrence of RMF, it is important for the dental practitioner to be aware of this variant and the possible complications which may occur during the administration of anesthesia and surgical procedures in the region.
The central neurocytoma is a supratentorial, often calcified brain tumour affecting young adults and is typically located in the lateral ventricles in the region of the foramen of Monro. Clinically, the tumour causes signs of increased intracranial pressure, visual and mental disturbances and, occasionally, pyramidal or endocrine symptoms. By light microscopy, the tumour is composed of small round cells in a delicate fibrillary matrix. Tumour cells consistently show features of neuronal differentiation by electron microscopy (synapses, dense-core vesicles, presynaptic clear vesicles, specialized synaptic junctions) and immunoreactivity for synaptophysin and other neuronal marker proteins. The tumour can be totally removed in nearly half of the cases. After incomplete surgical resection neurocytomas may recur but because of their low proliferation potential, radio- or chemotherapy are not generally recommended. Postoperative recurrence-free survival times of up to 19 years have been reported. Neurocytomas constitute nearly one half of supratentorial intraventricular tumours in adults but amount to less than 1% of all tumours of the central nervous system and its coverings.
OBJECTIVE: The Chiari I malformation is defined as tonsillar herniation of at least 3 to 5 mm below the foramen magnum. Although Chiari I malformation is considered to derive from a mesodermal disorder resulting in underdevelopment of the posterior fossa relative to its content, evidence for a possible heterogeneous etiology also has been reported. The aim of the present study is to elucidate the relationship between Chiari I malformation and mental retardation, speech delay, and epilepsy to consider a possible specific pathogenetic background. METHODS: Thirty-five patients with Chiari I malformations were identified by use of magnetic resonance imaging during a period between 1993 and 1999. The study consisted of nine patients (four boys and five girls) who were affected by mental retardation, speech delay, and epilepsy. All patients underwent electroencephalography and brain and cervical spine magnetic resonance imaging. RESULTS: All patients were mentally retarded with a mean intelligence quotient of 50. Seven patients had a positive history for speech delay, and five were epileptic. Electroencephalograms demonstrated abnormalities in seven patients. The mean tonsillar displacement was 10.1 mm. A thin corpus callosum and a wide cavum septum pellucidum were present in three patients. Neither hydromyelia nor scoliosis was observed. No correlation between the degree of the ectopia and clinical manifestation was noted. CONCLUSION: The association of Chiari I malformation with epilepsy, speech delay, and mental retardation may not be a mere incidental finding but may be a marker for a different pathogenetic background.
It is reported on a 19 year-old female patient with a mild mental retardation and a neurocutaneous syndrome. A tumour of a lateral ventricle had caused a partial blockade of the Foramen of Monro without symptoms of brain pressure. The patient shows lesions on the skin corresponding to a neurofibromatosis. Neurologically there was a choreatic syndrome, which can occur in transitional forms from neurofibromatosis to tuberous sclerosis (TS) of the brain. Psychologically a psychorganic syndrome, typical for TS, with disturbances of affectivity and motive developed. There was no essential improvement of the neurological and psychical symptoms by surgical removal of the brain tumour nor were there changes in the EEG except for an acceleration of the basic rhythm.
STUDY DESIGN: Case description. OBJECTIVES: To report 2 cases of vertebral artery injury (VAI) during anterior cervical decompression surgery and review the pertinent medical literature. SUMMARY OF BACKGROUND DATA: The incidence of VAI during an anterior surgical approach to the cervical spine is rare but potentially lethal. The spine surgeon should be aware of the detailed surgical anatomy and be prepared to manage an inadvertent injury to the vertebral artery. METHODS: In the first case presented, infection was the cause of VAI. During aggressive irrigation and pus drainage, massive bleeding was encountered. For the second case, the vertebral artery was injured during decompression of cervical spondylosis while drilling the neural foramen. Intraoperative direct packing with hemostatic agents provided effective control of hemorrhage. RESULTS: Ten days after surgery, sudden neck swelling and mental deterioration occurred because of rebleeding from a pseudoaneurysm in the first case. In the second case, a pseudoaneurysm was detected by angiography, obtained 4 days after surgery. Both pseudoaneurysms were successfully occluded by an endovascular technique without any neurologic sequelae. CONCLUSIONS: In case of bleeding control by hemostatic packing, there remains a risk of delayed hemorrhage from pseudoaneurysm. Postoperative vertebral angiography is helpful to avoid life-threatening complications. Endovascular treatment can be a good alternative in the treatment of VAI.
A 41-year-old man noticed colorless cutaneous nodules all over his body at the age of 24. Recently the nodules increased markedly in number and several large nodules were removed at the dermatological clinic of our hospital. The histological diagnosis of the nodules was neurofibroma. He was then referred to our neurosurgical clinic for neurological examinations to rule out involvement of the central nervous system. He showed no abnormality in neurological examination except for hyper-reflexia of the left patellar tendon reflex and occasional right leg weakness. Cranial CT scan and EEG were normal. Mental examination and routine laboratory studies were also normal. Vertebral scoliosis from C6 to T3 level, enlargement of the bilateral vertebral foramen at the level of T2 to T4, vertebral dysplasia of the C6 and T3, and the scalloping of the vertebral posterior margin of the T2 to T4 were seen in the plain X-ray films and tomography of the upper thoracic and cervical spine. The myelography and metrizamide CT scan showed multiple diverticular dilation of CSF space at the level of T1 to T4. This extended through the enlarged vertebral foramina to the chest cavity forming a dumb-bell shape. Spinal cord was normal and there was no tumor in the spinal canal. Dural ectasia and vertebral body scalloping were more clearly shown by magnetic resonance imaging (M.R.I). Dural ectasia accompanying von Recklinghausen's disease is rare and no MRI findings have been reported. Therefore, we reported this case and mainly discussed roentgenological findings and MRI of dural ectasia and other spinal abnormalities.
In view of the relevance of the mylohyoid nerve to clinical difficulties in achieving deep analgesia of the lower incisors, a dissection study was undertaken. Dissection from twenty-six adult cadavers of both sexes were studied with the aid of a dissecting microscope. The following observations were made: (1) A supplementary branch of the mylohyoid nerve entered the mandible through accessory foramina in the lingual side of the mandibular symphysis in 50% of the cases. (2) It generally arose from the right side (76.9%) and entered the inferior retromental foramen (84.6%). (3) The mylohyoid nerve branch either ended directly in the incisor teeth and the gingiva or joined the ipsilateral or contralateral incisive nerve. In view of this information concerning the high incidence of possible involvement of the mylohyoid nerve in mandibular sensory innervation, it is advisable to block it whenever intervention in the lower incisors is indicated. Routine mylohyoid injection is recommended after mental nerve block. If the inferior alveolar nerve is chosen for anesthetic purposes, additional mylohyoid injection should be given only if pain persists. The mylohyoid injection should be given at the inferior retromental foramen on the median aspect of the inferior border of the mandible through extraoral approach.
OBJECTIVE: To report a case of subependymal giant cell astrocytoma (SEGA) in a patient with tuberous sclerosis, emphasizing the proton MR spectroscopy (MRS) findings. CASE: A three year-old boy with tuberous sclerosis presented with a 3-month history of mild headache. The physical examination showed discrete mental retardation and multiple hypomelanic macules in the legs and back. MRI showed many cortical tubers and subependymal nodules. At the left foramen of Monro, there was a 15 mm nodule, with heterogeneous signal on T1 and T2-weighted images, and strong enhancement after contrast administration. MRS study (multi-voxel PRESS, TE=144ms) showed the following ratios: a) left foramen of Monro nodule N-acetylaspartate (NAA)/creatine (Cr)=0.93 and Choline (Cho)/Cr=1.6 and b) at the right Monro foramen NAA/Cr=1.56 and Cho/Cr=1.29. CONCLUSION: The MRS performed at the SEGA may show high Cho/Cr and low NAA/Cr ratios, similar to the other brain neoplasms. As a consequence, MRS may be a valuable tool for the early detection of neoplastic transformation of subependymal nodules near the foramina of Monro in patients with tuberous sclerosis.
Carpenter syndrome consists of acrocephaly, soft tissue syndactyly, short fingers, preaxial polydactyly, congenital heart disease, hypogenitalism, cryptorchidism, obesity, umbilical hernia and mental retardation. Here we report two affected sibs (IQs were 80 and 93) presenting various cerebrospinal malformations, i.e. frontal lobe deformity, narrowed foramen magnum, hypoplastic posterior fossa, kinked spinal cord, and syrinx cavitation demonstrated by magnetic resonance imaging.
Of 10 children with macrocephaly in association with achondroplasia only two children had progressive hydrocephalus. They were treated with a shunt procedure. One of these is intellectually and neurologically normal, and one is wheelchair bound and mentally retarded, with a spastic quadraplegia. Three children showed mild dilatation of the ventricles and one of these died from severe constriction at the foramen magnum. The other two are neurologically normal; one is intellectually normal but below average (WISC 88) and the other is slow normal at 18 months of age. Four children with demonstrated megalencephaly and a fifth with probable megalencephaly are all intellectually and neurologically normal. Intelligence in achondroplasia appears to be mainly in the normal range.